MANUFACTURING METHOD OF FeCoV BASED SOFT MAGNETIC STEEL SHEET HAVING SPECIFIC DIRECTIONAL STRUCTURE

Abstract

A method for manufacturing a FeCoV alloy-based thin sheet according to the present invention comprises the steps of: preparing a FeCoV alloy molten metal; casting the alloy molten metal to produce an ingot; hot rolling the ingot to obtain a sheet; heat treating the sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated sheet; and cold rolling the rapidly cooled sheet to obtain a FeCoV alloy-based thin sheet; wherein the FeCoV alloy-based thin sheet is characterized in that the intensity of the peak of the (100) plane among the peaks of the X-ray diffraction pattern of the ingot is reduced or does not appear.

Description

Technology Field

[0001] The present invention relates to a method for manufacturing a FeCoV alloy-based thin sheet, a FeCoV alloy-based thin sheet and a driving motor using the same, specifically a method for manufacturing a FeCoV alloy-based soft magnetic thin sheet, a FeCoV alloy-based soft magnetic thin sheet and a driving motor using the same. Background Technology

[0002] Generally, magnetic materials are materials that possess magnetic properties. Among these, soft magnetic materials can exhibit both magnetic and non-magnetic characteristics, allowing for the selective use of magnetic properties in a desired direction. Notably, soft magnetic materials have been used as motor core materials and applied to various electronic products; recently, with the rapid rise of electric vehicles, they are receiving significant attention as materials for drive motors.

[0003] Materials for electric vehicle drive motors must possess a high saturation magnetic flux density to increase motor output. Furthermore, to improve motor efficiency—which is related to how long a single battery can be used—iron loss, representing the loss incurred when implementing magnetic properties, must be low.

[0004] Although the composition of FeCoV-based alloys varies slightly depending on the target characteristics, they are alloys with high saturation magnetic flux density and low iron loss. While their application has been limited due to high material costs, they are recently making a rapid resurgence. Manufacturing FeCoV-based alloys into thin sheets requires highly complex processes such as vacuum melting, slag removal, forging, and cold rolling.

[0005] In addition, FeCoV-based alloys have a regular microstructure, which results in high strength and somewhat low elongation. Consequently, cracking or splitting occurs during the cold rolling process, making it difficult to roll to the target thickness.

[0006] Therefore, there is a need to develop a manufacturing method for FeCoV alloy-based thin sheets that is simple to manufacture, easy to cold roll, and capable of reducing process costs. The problem to be solved

[0007] The present invention aims to provide a method for manufacturing a FeCoV alloy-based thin sheet that is simple to manufacture, facilitates cold rolling to a target thickness, and reduces process costs.

[0008] In addition, the present invention aims to provide a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value and low iron loss.

[0009] In addition, the present invention aims to provide a drive motor with excellent driving efficiency. means of solving the problem

[0010] The present invention provides a method for manufacturing a FeCoV alloy-based thin sheet, comprising the steps of: preparing a FeCoV alloy molten metal; casting the alloy molten metal to produce an ingot; hot rolling the ingot to obtain a sheet; heat treating the sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated sheet; and cold rolling the rapidly cooled sheet to obtain a FeCoV alloy-based thin sheet; wherein the FeCoV alloy-based thin sheet is such that the intensity of the peak of the (100) plane among the peaks of the X-ray diffraction pattern of the ingot is reduced or does not appear. Effects of the invention

[0011] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of being able to manufacture a FeCoV alloy-based thin sheet having high saturation magnetic flux density and low iron loss without undergoing conventional complex processes. In addition, it has the advantage of reducing process costs.

[0012] In addition, the FeCoV alloy-based thin sheet according to the present invention has the advantage of having a high saturation magnetic flux density and low iron loss.

[0013] In addition, the drive motor according to the present invention has the advantage of excellent driving efficiency. Brief explanation of the drawing

[0014] FIGS. 1a and 1b show Fe prepared according to some embodiments of the present invention. 49 Co 49 This is a diagram showing the measurement results of the elongation and tensile strength of the V2 sheet metal. FIGS. 2a and 2b show Fe manufactured according to some embodiments of the present invention. 49 Co 49 This is a diagram showing the XRD analysis results of the V2 thin plate. FIGS. 3a and 3b show Fe manufactured according to some embodiments of the present invention. 49 Co 49 This is a figure showing the change in iron loss value at 400Hz with a magnetic flux density of 5000A / m and 1T applied to the V2 sheet. FIG. 4 shows Fe manufactured according to some embodiments of the present invention 49 Co 49 This is a diagram showing the SEM image of the V2 thin plate. FIGS. 5 to 7 show Fe manufactured according to some embodiments of the present invention. 49 Co 49 This is a diagram showing the OM image of the lateral cross-sectional structure of the V2 sheet. FIGS. 8a to 8c illustrate Fe according to some embodiments of the present invention 49 Co 49 This is a diagram showing the XRD patterns of each specimen during the manufacturing process of the V2 thin plate. FIGS. 9a to 9c illustrate Fe according to some embodiments of the present invention 49 Co 49 This is a diagram showing SEM images of each specimen during the manufacturing process of the V2 thin plate. FIGS. 10a to 10d are Fe manufactured according to some embodiments of the present invention 49 Co 49This is a diagram showing the GDS surface analysis results of the V2 thin plate specimen. FIGS. 11a and 11b illustrate Fe according to some embodiments of the present invention 49 Co 49 This is a diagram showing the XRD patterns of each specimen during the manufacturing process of the V2 thin plate. FIG. 12 shows Fe manufactured according to some embodiments of the present invention 49 Co 49 This is a diagram showing the hysteresis of the V2 sheet. FIGS. 13a to 13d illustrate Fe according to some embodiments of the present invention 49 Co 49 This is a diagram showing the XRD patterns of each specimen during the manufacturing process of the V2 thin plate. FIGS. 14a to 14e illustrate Fe according to some embodiments of the present invention 49 Co 49 This is a diagram showing SEM images of each specimen during the manufacturing process of the V2 thin plate. FIGS. 15a and 15b show Fe manufactured according to some embodiments of the present invention. 49 Co 49 This is a diagram showing the SEM image of the V2 thin plate. Specific details for implementing the invention

[0015] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0016] In the present invention, when it is stated that a certain member is located "on" another member, this includes not only cases where a certain member is in direct contact with another member, but also cases where another member is interposed between the two members.

[0017] In the present invention, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0019] One aspect of the present invention relates to a method for manufacturing a FeCoV alloy-based thin sheet, comprising the steps of: preparing a FeCoV alloy molten metal by vacuum melting an alloy composition consisting of 20 to 49 at% cobalt, 2 to 5 at% vanadium, and the remainder being iron and other impurities; casting the alloy molten metal to produce an ingot; hot rolling the ingot to obtain a sheet; heat treating the sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated sheet; and cold rolling the rapidly cooled sheet to obtain a FeCoV alloy-based thin sheet.

[0020] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes a step of changing at least a portion of the α-ferrite phase into a γ-austenite phase, thereby enabling easy cold rolling and having the advantage of being able to manufacture a FeCoV alloy-based thin sheet having excellent saturation magnetic flux density and low iron loss value without undergoing complex processes such as conventional forging.

[0022] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of preparing a FeCoV alloy molten metal by vacuum melting an alloy component composed of 20 to 49 at% cobalt, 2 to 5 at% vanadium, and the remainder being iron and other impurities.

[0023] The above other impurities may be one or more selected from the group consisting of carbon, oxygen, silicon, and manganese.

[0024] In one embodiment of the present invention, the FeCoV alloy molten metal may comprise an alloy composition consisting of 30 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0025] In another embodiment of the present invention, the FeCoV alloy molten metal may comprise an alloy composition consisting of 40 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0026] FeCoV-based alloys are alloy compositions with soft magnetic properties. Manufactured into thin sheets, they are primarily used in motor cores for electronic products, and recently, their application as drive motors for electric vehicles is being considered.

[0027] To increase the output of electric vehicles, the magnetic flux density of the motor core material must be high. Most recent electric vehicles have values ​​exceeding 2 Tesla, and since FeCoV alloys can reach up to 2.4 Tesla, they can be highly beneficial for improving motor core output. Furthermore, they possess significantly lower iron loss values ​​compared to other soft magnetic materials, which not only improves efficiency but also enables longer driving distances due to lower losses relative to batteries of the same capacity. For the same reasons, it is possible to miniaturize and lighten motors that exhibit the same performance.

[0028] For such FeCoV alloys, the rolling process defect rate can vary depending on the manufacturing process, even if the alloy composition is the same, and the mechanical and magnetic properties of the manufactured sheet can be significantly affected.

[0029] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of easily manufacturing a thin sheet having high mechanical and magnetic properties without including conventional complex slag removal processes, forging processes, and slab shape forming processes.

[0030] Meanwhile, the saturation magnetic flux density and coercivity values ​​of the FeCoV alloy-based thin sheet manufactured according to the composition of the above FeCoV alloy components may vary slightly.

[0031] In the present invention, by using an FeCoV alloy component having the composition described above, there is an advantage in obtaining a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value and low coercivity.

[0032] The above FeCoV alloy molten metal is Fe 49 Co 49 It can have V2 composition.

[0033] By vacuum melting the above alloy components, a grayish ingot with low contamination can be obtained, and when solidified into an ingot shape through the casting step described later, it is desirable to suppress the phenomenon in which an ingot with an uneven composition is obtained due to compositional inconsistency, such as when the composition of the upper and middle parts or the middle and lower parts of the ingot differs, or when segregation exists in the same part. In addition, it is desirable to suppress the phenomenon in which cracks are induced during hot rolling, cold rolling, etc., due to the oxide layer being too thick.

[0035] The step of preparing the molten alloy may be performed under an argon, nitrogen, or carbon dioxide atmosphere. It is preferable that the step of preparing the molten alloy be performed under an argon, nitrogen, or carbon dioxide atmosphere, as this can suppress the oxidation or carbonization of the alloy components.

[0037] In the step of preparing a molten FeCoV alloy by vacuum melting the above alloy components, the vacuum level is 1×10 -2 Up to 1×10 -4 torr, preferably 1×10 -2 Up to 1×10 -3 It could be torr.

[0038] If the above vacuum level satisfies the above range, it is desirable to be able to suppress oxidation or carbonization.

[0040] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of manufacturing an ingot by casting the molten alloy.

[0041] The method may further include, but is not limited to, a step of removing slag from the molten alloy liquid prior to casting the molten alloy.

[0042] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may not include a step of removing slag from the molten alloy. Specifically, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of being able to manufacture a FeCoV alloy-based thin sheet exhibiting excellent performance without including a slag removal process, a forging process, or a shape-controlled sraving process.

[0043] The method of manufacturing an ingot by casting the above-mentioned molten alloy is not specifically limited in the present invention.

[0044] For example, the molten alloy can be poured into a mold and cooled and crystallized to produce an ingot.

[0045] It is preferable that the injection temperature be 100 to 2000°C, preferably 100 to 1000°C, and more preferably 200 to 500°C higher than the liquid phase temperature of the molten metal. The liquid phase temperature of the molten metal can be measured using a direct temperature measurement method with a built-in thermocouple or by using a non-contact laser thermometer on the surface of the molten metal.

[0046] In addition, the cooling temperature and speed can be controlled to ensure uniformity of composition and prevent segregation. Since the upper part of the ingot cools relatively quickly while the lower part or interior cools slowly, the parts that cool quickly can be heated, or they can be insulated with non-metallic ceramics or slag.

[0048] The above ingot may be manufactured in the shape of, for example, a bar, a polyhedron, a cylinder, a sphere, or an irregular shape, but is not limited thereto.

[0049] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may further include the step of cutting the ingot into 4 to 30 mm.

[0050] For example, the method for manufacturing the above FeCoV alloy-based thin sheet may further include a step of cutting the ingot into 10 to 30 mm. It is desirable to further include a step of cutting the ingot within the above range so that hot rolling is smooth.

[0051] The cutting of the above ingot may be carried out by methods conventionally performed in the art, and the present invention is not limited thereto.

[0053] In another embodiment of the present invention, the method may further include the step of manufacturing an ingot by casting the molten alloy; and the step of homogenizing the ingot thereafter.

[0054] In another embodiment of the present invention, the homogenization heat treatment may be performed at 1200 to 1300°C for 1 to 12 hours.

[0055] Preferably, the homogenization heat treatment may be performed for 2 to 6 hours, more preferably for 2 to 4 hours, but is not limited thereto.

[0056] It is desirable to further include the above homogenization heat treatment step so that stress generated during casting can be relieved.

[0058] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of hot rolling the ingot to obtain a sheet material.

[0059] It is desirable to obtain a plate in which the γ-austenite phase formed by slow cooling accounts for the majority, or in which the α-ferrite phase and the γ-austenite phase are mixed by hot rolling the above ingot.

[0061] The above hot rolling can be performed, for example, using a steel rolling mill.

[0062] The above rolling start temperature, rolling speed, rolling end temperature, etc., are not specifically limited in the present invention and can be appropriately performed under ordinary conditions practiced in the industry.

[0063] For example, the starting temperature for the above rolling may be 900°C or higher and may not exceed 1300°C. When the starting temperature for the above rolling satisfies the above range, it is desirable as there is an advantage of excellent strength and formability of the sheet material being manufactured.

[0064] The above rolling end temperature may be 1150℃ or higher. When the above rolling end temperature is 1150℃ or higher, it is desirable because it can suppress the phenomenon of strain on the equipment due to high deformation resistance and facilitate shape control.

[0066] The total reduction rate by the above hot rolling may be 70 to 90%, preferably 75 to 90%, and more preferably 75 to 85%. When the total reduction rate satisfies the above range, it is desirable to suppress the increase of crystal grains caused by high energy and to reduce the deviation thereof.

[0068] The above rolling may be performed in one to several passes, but is not limited thereto.

[0069] In another embodiment of the present invention, the rolling may be performed in two or more rolling passes. Specifically, the rolling may be performed in five or more rolling passes, but is not limited thereto.

[0071] If the temperature decreases as the above hot rolling is repeated, it is desirable to raise the temperature by reheating and then perform hot rolling. It is desirable to control the lower limit of the temperature during the rolling process to 900°C or higher, preferably 900 to 1000°C.

[0072] When the lower limit of the temperature during the above rolling process satisfies the above range, it is desirable because it exists mostly in the γ-austenite phase, so cracks and bursting hardly occur during hot rolling and it becomes smooth.

[0074] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of heat-treating the sheet material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase.

[0075] Although I do not wish to be limited by theory, generally, FeCoV-based alloys undergo phase changes as they go through casting, hot rolling, heat treatment, and cold rolling processes, and even within the same phase, they change into regular and irregular lattices.

[0076] For example, when a FeCoV-based alloy is melted in a vacuum and cast into an ingot, an α-ferrite phase is formed.

[0077] In the case of α-ferrite, which is a microstructure at room temperature, it has a body-centered cubic (BCC) structure and relatively few slip planes, so there is a high possibility that cold rolling will not be performed smoothly when using FeCoV alloy-based sheet materials to make thin sheets.

[0078] In particular, due to residual stress present within the sheet metal after cold rolling, forming becomes difficult and soft magnetic properties may not be properly realized.

[0079] On the other hand, the γ-austenite structure, which is a high-temperature structure, has an irregular face-centered cubic (FCC) structure and has many slip planes, making it easy to roll, and thus its plastic workability is much better than that of α-ferrite.

[0080] Accordingly, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention involves heat-treating the sheet material at a temperature of 600 to 1200°C, which is a high-temperature stable phase region, so that it has a γ-austenite structure, which is a high-temperature stable phase, in other words, an FCC structure, and then rapidly cooling it, thereby changing the α-ferrite phase generated through the casting process and hot rolling process into a γ-austenite phase, so that it has a γ-austenite phase or a structure having a composite structure of an α-ferrite phase and a γ-austenite phase.

[0081] In another embodiment of the present invention, the heat treatment may be performed at a temperature of 730 to 1200°C. Specifically, the heat treatment may be performed at a temperature of 730°C or higher, which is the temperature at which ordering of irregular / ordered lattice structures begins, and at a temperature of 1200°C or lower, which is the temperature at which atomic structure changes are expected to be most active without the formation of a liquid phase. Specifically, it is preferable that the heat treatment be performed within the above range, which is the temperature region where irregular / ordered structural changes occur.

[0083] In another embodiment of the present invention, the heat treatment may be performed at 840 to 1200°C.

[0084] Specifically, the above heat treatment can be performed at a temperature of 840°C or higher, which is the temperature at which phase transformation occurs, and at a temperature of 1200°C or lower, which is the temperature at which solid phase control is possible without the presence of a liquid phase.

[0085] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be heat treatment at 850 to 950°C.

[0086] Since FeCoV alloy-based sheet materials can vary significantly in mechanical and / or magnetic properties depending on the heat treatment temperature even with the same composition, the present invention allows for obtaining a FeCoV alloy-based thin sheet with excellent mechanical properties and superior magnetic properties—that is, having high saturation magnetic flux density and low iron loss values ​​simultaneously—by heat treating at a temperature within the above range.

[0088] In another embodiment of the present invention, the heat treatment may be performed for 30 to 240 minutes.

[0089] Preferably, the heat treatment can be performed for 60 to 120 minutes.

[0090] When the above heat treatment time satisfies the above range, it is desirable because the phase transformation time to the γ-austenite phase is sufficient while shortening the heat treatment time.

[0091] In short, the step of changing to the γ-austenite phase may be heat treatment at a temperature of 850 to 950°C for 60 to 120 minutes.

[0093] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be performed under a vacuum or an inert gas atmosphere. Since the FeCoV-based alloy is somewhat prone to oxidation, it is preferable to perform the step of changing to the γ-austenite phase under a vacuum or an inert gas atmosphere.

[0094] The above inert gas may be, for example, high-purity argon (Ar) gas, but is not limited thereto.

[0096] In another embodiment of the present invention, a step of removing surface scale from the plate material may be further included prior to the step of heat-treating the plate material.

[0097] An oxide scale may form on the surface of the hot-rolled sheet metal. Since the oxide scale can affect the quality of the sheet metal, it is desirable to further include a step of removing the surface scale from the sheet metal.

[0098] The method for removing surface scale from the above-mentioned plate can be performed using conventional methods practiced in the industry.

[0099] For example, the above-mentioned plate may be immersed in a hydrochloric acid bath to perform pickling treatment, or a slurry mixed with high-pressure water and abrasive may be sprayed at high pressure onto the above-mentioned plate to remove the surface scale, but is not limited thereto.

[0101] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of quenching the heat-treated FeCoV alloy-based sheet material.

[0102] In the cold rolling process described later, if the microstructure of the above FeCoV alloy-based sheet material forms an regular structure, it has high strength and low elongation, which causes cracking or splitting to occur during the cold rolling process, making it difficult to roll to the target thickness.

[0103] Accordingly, in the present invention, the FeCoV alloy-based plate is heat-treated at 600 to 1200°C for 10 to 240 minutes to change the α-ferrite phase into a γ-austenite phase, thereby changing the FeCoV alloy-based plate to form a disordered structure.

[0104] After that, by including a step of rapidly cooling the above FeCoV alloy-based sheet so that it can maintain the structure of the γ-austenite phase, the elongation is improved and the problem occurring during the cold rolling process is solved.

[0105] In another embodiment of the present invention, the rapid cooling step may be rapid cooling at a rate of 10 to 300°C / sec. Preferably, the rapid cooling may be performed at a rate of 30 to 150°C / sec, more preferably at a rate of 50 to 100°C / sec.

[0106] It is desirable that when the rate of rapid cooling satisfies the above range, the γ-austenite phase is stably maintained, allowing for the production of a FeCoV alloy-based thin sheet having a high saturation magnetic flux density.

[0107] The above rapid cooling step may involve performing water cooling or oil cooling.

[0108] The above water cooling or oil cooling method is not specifically limited in the present invention, and general methods practiced in the art may be applied. For example, it may be performed using a water or oil cooling guide and a conveyor roll, but is not limited thereto.

[0109] By performing the above water cooling or oil cooling, the γ-austenite phase structure, which is a high-temperature stable phase, can be stably maintained.

[0110] The above rapid cooling step may be performed by immersing the FeCoV-based alloy plate in cooling water.

[0112] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of cold-rolling the rapidly cooled FeCoV alloy-based sheet material to obtain a FeCoV alloy-based thin sheet.

[0113] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention allows for smooth cold rolling by heat-treating an α-ferrite phase with a regular structure according to a specific temperature range and time, and then rapidly cooling it to change it into a γ-austenite phase with an irregular structure.

[0114] The above cold rolling may be performed repeatedly while varying the reduction ratio, but is not limited thereto.

[0115] The cumulative reduction rate may be 85% or more, specifically 90% or more, and more specifically 95% or more, but is not limited to this.

[0117] In another embodiment of the present invention, the method may further include the step of obtaining the FeCoV alloy-based thin sheet; and subsequently the step of performing stress relief heat treatment on the FeCoV alloy-based thin sheet.

[0118] By including a step of stress relief heat treatment of the above FeCoV alloy-based thin sheet, residual stress present inside the FeCoV alloy-based thin sheet after cold rolling can be removed, and regularity is ensured as the irregular γ-austenite phase changes into a stable phase, thereby making it desirable to obtain a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value, a low iron loss value, and appropriate tensile strength and elongation.

[0120] Soft magnetic FeCoV alloys undergo a process in which the phase of the microstructure changes during the manufacturing process of thin sheets, and in this process, the specific method of heat treatment, such as the heat treatment atmosphere, temperature, and time, affects the values ​​of magnetic properties, such as saturation magnetic flux density, residual magnetic flux density, coercivity, and core loss.

[0121] Here, when soft magnetic materials are used as materials for drive motor components, they exhibit characteristics where higher saturation magnetic flux density or magnetic flux density values ​​in a specific frequency range are advantageous, and lower loss values ​​such as iron loss are advantageous. Consequently, alloy design, processing, and heat treatment are carried out to achieve high magnetic flux density and low iron loss values. As a result, when the value obtained by dividing magnetic flux density by iron loss is defined as the high-efficiency value, the higher this value, the better the material is for motors.

[0122] In the present invention, heat treatment for microstructure control is performed between hot rolling and cold rolling to facilitate cold rolling, and additional stress relief heat treatment is performed after cold rolling to improve mechanical properties, particularly elongation and magnetic properties, thereby providing the advantage of being able to manufacture FeCoV alloy-based thin sheets with excellent mechanical and magnetic properties.

[0123] In another embodiment of the present invention, the stress relief heat treatment may be performed at 650 to 950°C for 10 to 120 minutes.

[0124] Preferably, the stress relief heat treatment may be performed at a temperature of 700 to 950°C, more preferably 850 to 950°C, but is not limited thereto.

[0126] One aspect of the present invention relates to a method for manufacturing a FeCoV alloy-based thin sheet, comprising the steps of: preparing a FeCoV alloy-based sheet; heat-treating the FeCoV alloy-based sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated FeCoV alloy-based sheet; cold-rolling the rapidly cooled FeCoV alloy-based sheet to obtain a FeCoV alloy-based thin sheet; and stress-relieving heat-treating the FeCoV alloy-based thin sheet.

[0127] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes a step of changing at least a portion of the α-ferrite phase into a γ-austenite phase, thereby facilitating cold rolling, and includes a step of stress relief heat treatment of the FeCoV alloy-based thin sheet, thereby improving mechanical properties, particularly elongation and magnetic properties, and has the advantage of being able to manufacture a FeCoV alloy-based thin sheet having excellent saturation magnetic flux density and low iron loss value without undergoing complex processes such as conventional forging.

[0129] A method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of preparing a FeCoV alloy-based sheet material.

[0130] The step of preparing the above-mentioned FeCoV alloy-based sheet is not limited in the present invention. For example, the above-mentioned FeCoV alloy-based sheet may be purchased from the market or manufactured directly.

[0132] In another embodiment of the present invention, the step of preparing an FeCoV alloy-based plate may include: preparing a FeCoV alloy molten metal by vacuum melting an alloy composition consisting of 20 to 49 at% cobalt, more than 0 to 5 at% vanadium, 0 to 15 at% nickel, 0 to 3 wt% chromium, 0 to 1 at% niobium, and the remainder being iron and other impurities; casting the alloy molten metal to produce an ingot; and hot rolling the ingot to obtain an FeCoV alloy-based plate.

[0133] The above other impurities may be one or more selected from the group consisting of carbon, oxygen, silicon, and manganese.

[0134] Specifically, the above-mentioned FeCoV alloy molten metal may contain alloy components composed of 30 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0135] More specifically, the above-mentioned FeCoV alloy molten metal may contain alloy components composed of 40 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0136] FeCoV-based alloys are alloy compositions with soft magnetic properties. Manufactured into thin sheets, they are primarily used in motor cores for electronic products, and recently, their application as drive motors for electric vehicles is being considered.

[0137] To increase the output of electric vehicles, the magnetic flux density of the motor core material must be high. Most recent electric vehicles have values ​​exceeding 2 Tesla, and since FeCoV alloys can reach up to 2.4 Tesla, they can be highly beneficial for improving motor core output. Furthermore, they possess significantly lower iron loss values ​​compared to other soft magnetic materials, which not only improves efficiency but also enables longer driving distances due to lower losses relative to batteries of the same capacity. For the same reasons, it is possible to miniaturize and lighten motors that exhibit the same performance.

[0138] For such FeCoV alloys, the rolling process defect rate can vary depending on the manufacturing process, even if the alloy composition is the same, and the mechanical and magnetic properties of the manufactured sheet can be significantly affected.

[0139] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of easily manufacturing a thin sheet having high mechanical and magnetic properties without including conventional complex slag removal processes, forging processes, and slab shape forming processes.

[0140] Meanwhile, the saturation magnetic flux density and coercivity values ​​of the FeCoV alloy-based thin sheet manufactured according to the composition of the above FeCoV alloy components may vary slightly.

[0141] When using FeCoV alloy components having the composition described above, there is an advantage in obtaining FeCoV alloy-based thin sheets having a high saturation magnetic flux density value and low coercivity.

[0142] The above FeCoV alloy molten metal is Fe 49 Co 49 It can have V2 composition.

[0143] By vacuum melting the above alloy components, a grayish ingot with low contamination can be obtained, and when solidified into an ingot shape through the casting step described later, it is desirable to suppress the phenomenon in which an ingot with an uneven composition is obtained due to compositional inconsistency, such as when the composition of the upper and middle parts or the middle and lower parts of the ingot differs, or when segregation exists in the same part. In addition, it is desirable to suppress the phenomenon in which cracks are induced during hot rolling, cold rolling, etc., due to the oxide layer being too thick.

[0145] The step of preparing the molten alloy may be performed under an argon, nitrogen, or carbon dioxide atmosphere. It is preferable that the step of preparing the molten alloy be performed under an argon, nitrogen, or carbon dioxide atmosphere, as this can suppress the oxidation or carbonization of the alloy components.

[0147] In the step of preparing a molten FeCoV alloy by vacuum melting the above alloy components, the vacuum level is 1×10 -2 Up to 1×10 -4 torr, preferably 1×10 -2 Up to 1×10 -3 It could be torr.

[0148] If the above vacuum level satisfies the above range, it is desirable to be able to suppress oxidation or carbonization.

[0150] The method may further include, but is not limited to, a step of removing slag from the molten alloy liquid prior to casting the molten alloy.

[0151] Alternatively, the step of removing slag from the molten alloy liquid before casting the molten alloy may not be included, but is not limited thereto.

[0152] The method of manufacturing an ingot by casting the above-mentioned molten alloy is not specifically limited in the present invention.

[0153] For example, the molten alloy can be poured into a mold and cooled and crystallized to produce an ingot.

[0154] It is preferable that the injection temperature be 100 to 2000°C, preferably 100 to 1000°C, and more preferably 200 to 500°C higher than the liquid phase temperature of the molten metal. The liquid phase temperature of the molten metal can be measured using a direct temperature measurement method with a built-in thermocouple or by using a non-contact laser thermometer on the surface of the molten metal.

[0155] In addition, the cooling temperature and speed can be controlled to ensure uniformity of composition and prevent segregation. Since the upper part of the ingot cools relatively quickly while the lower part or interior cools slowly, the parts that cool quickly can be heated, or they can be insulated with non-metallic ceramics or slag.

[0157] The above ingot may be manufactured in the shape of, for example, a bar, a polyhedron, a cylinder, a sphere, or an irregular shape, but is not limited thereto.

[0158] The step of preparing the above FeCoV alloy-based plate may further include the step of cutting the above ingot into 4 to 30 mm pieces.

[0159] For example, the method for manufacturing the above FeCoV alloy-based thin sheet may further include a step of cutting the ingot into 10 to 30 mm. It is desirable to further include a step of cutting the ingot within the above range so that hot rolling is smooth.

[0160] The cutting of the above ingot may be carried out by methods conventionally performed in the art, and the present invention is not limited thereto.

[0162] The method may further include the step of manufacturing an ingot by casting the above-mentioned molten alloy; and the step of homogenizing the ingot thereafter.

[0163] The above homogenization heat treatment may be performed at 1200 to 1300°C for 1 to 12 hours.

[0164] Preferably, the homogenization heat treatment may be performed for 2 to 6 hours, more preferably for 2 to 4 hours, but is not limited thereto.

[0165] It is desirable to further include the above homogenization heat treatment step so that stress generated during casting can be relieved.

[0167] The step of preparing the above FeCoV alloy-based plate may include the step of obtaining a plate by hot rolling the above ingot.

[0168] It is desirable to obtain a plate in which the γ-austenite phase formed by slow cooling accounts for the majority, or in which the α-ferrite phase and the γ-austenite phase are mixed by hot rolling the above ingot.

[0170] The above hot rolling can be performed, for example, using a steel rolling mill.

[0171] The above rolling start temperature, rolling speed, rolling end temperature, etc., are not specifically limited in the present invention and can be appropriately performed under ordinary conditions practiced in the industry.

[0172] For example, the starting temperature for the above rolling may be 900°C or higher and may not exceed 1300°C. When the starting temperature for the above rolling satisfies the above range, it is desirable as there is an advantage of excellent strength and formability of the sheet material being manufactured.

[0173] The above rolling end temperature may be 1150℃ or higher. When the above rolling end temperature is 1150℃ or higher, it is desirable because it can suppress the phenomenon of strain on the equipment due to high deformation resistance and facilitate shape control.

[0175] The total reduction rate by the above hot rolling may be 70 to 90%, preferably 75 to 90%, and more preferably 75 to 85%. When the total reduction rate satisfies the above range, it is desirable to suppress the increase of crystal grains caused by high energy and to reduce the deviation thereof.

[0177] The above rolling may be performed in one to several passes, but is not limited thereto.

[0178] In another embodiment of the present invention, the rolling may be performed in two or more rolling passes. Specifically, the rolling may be performed in five or more rolling passes, but is not limited thereto.

[0180] If the temperature decreases as the above hot rolling is repeated, it is desirable to raise the temperature by reheating and then perform hot rolling. It is desirable to control the lower limit of the temperature during the rolling process to 900°C or higher, preferably 900 to 1000°C.

[0181] When the lower limit of the temperature during the above rolling process satisfies the above range, it is desirable because it exists mostly in the γ-austenite phase, so cracks and bursting hardly occur during hot rolling and it becomes smooth.

[0183] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of heat-treating the sheet material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase.

[0184] Although I do not wish to be limited by theory, generally, FeCoV-based alloys undergo phase changes as they go through casting, hot rolling, heat treatment, and cold rolling processes, and even within the same phase, they change into regular and irregular lattices.

[0185] For example, when a FeCoV-based alloy is melted in a vacuum and cast into an ingot, an α-ferrite phase is formed.

[0186] In the case of α-ferrite, which is a microstructure at room temperature, it has a body-centered cubic (BCC) structure and relatively few slip planes, so there is a high possibility that cold rolling will not be performed smoothly when using FeCoV alloy-based sheet materials to make thin sheets.

[0187] In particular, due to residual stress present within the sheet metal after cold rolling, forming becomes difficult and soft magnetic properties may not be properly realized.

[0188] On the other hand, the γ-austenite structure, which is a high-temperature structure, has an irregular face-centered cubic (FCC) structure and has many slip planes, making it easy to roll, and thus its plastic workability is much better than that of α-ferrite.

[0189] Accordingly, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention involves heat-treating the sheet material at a temperature of 600 to 1200°C, which is a high-temperature stable phase region, so that it has a γ-austenite structure, which is a high-temperature stable phase, in other words, an FCC structure, and then rapidly cooling it, thereby changing the α-ferrite phase generated through the casting process and hot rolling process into a γ-austenite phase, so that it has a γ-austenite phase or a structure having a composite structure of an α-ferrite phase and a γ-austenite phase.

[0190] In another embodiment of the present invention, the heat treatment may be performed at a temperature of 730 to 1200°C. Specifically, the heat treatment may be performed at a temperature of 730°C or higher, which is the temperature at which ordering of irregular / ordered lattice structures begins, and at a temperature of 1200°C or lower, which is the temperature at which atomic structure changes are expected to be most active without the formation of a liquid phase. Specifically, it is preferable that the heat treatment be performed within the above range, which is the temperature region where irregular / ordered structural changes occur.

[0192] In another embodiment of the present invention, the heat treatment may be performed at 840 to 1200°C.

[0193] Specifically, the above heat treatment can be performed at a temperature of 840°C or higher, which is the temperature at which phase transformation occurs, and at a temperature of 1200°C or lower, which is the temperature at which solid phase control is possible without the presence of a liquid phase.

[0194] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be heat treatment at 850 to 950°C.

[0195] Since FeCoV alloy-based sheet materials can vary significantly in mechanical and / or magnetic properties depending on the heat treatment temperature even with the same composition, the present invention allows for obtaining a FeCoV alloy-based thin sheet with excellent mechanical properties and superior magnetic properties—that is, having high saturation magnetic flux density and low iron loss values ​​simultaneously—by heat treating at a temperature within the above range.

[0197] In another embodiment of the present invention, the heat treatment may be performed for 30 to 240 minutes.

[0198] Preferably, the heat treatment can be performed for 60 to 120 minutes.

[0199] When the above heat treatment time satisfies the above range, it is desirable because the phase transformation time to the γ-austenite phase is sufficient while shortening the heat treatment time.

[0200] In short, the step of changing to the γ-austenite phase may be heat treatment at a temperature of 850 to 950°C for 60 to 120 minutes.

[0202] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be performed under a vacuum or an inert gas atmosphere. Since the FeCoV-based alloy is somewhat prone to oxidation, it is preferable to perform the step of changing to the γ-austenite phase under a vacuum or an inert gas atmosphere.

[0203] The above inert gas may be, for example, high-purity argon (Ar) gas, but is not limited thereto.

[0205] In another embodiment of the present invention, a step of removing surface scale from the plate material may be further included prior to the step of heat-treating the plate material.

[0206] An oxide scale may form on the surface of the hot-rolled sheet metal. Since the oxide scale can affect the quality of the sheet metal, it is desirable to further include a step of removing the surface scale from the sheet metal.

[0207] The method for removing surface scale from the above-mentioned plate can be performed using conventional methods practiced in the industry.

[0208] For example, the above-mentioned plate may be immersed in a hydrochloric acid bath to perform pickling treatment, or a slurry mixed with high-pressure water and abrasive may be sprayed at high pressure onto the above-mentioned plate to remove the surface scale, but is not limited thereto.

[0210] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of quenching the heat-treated FeCoV alloy-based sheet material.

[0211] In the cold rolling process described later, if the microstructure of the above FeCoV alloy-based sheet material forms an regular structure, it has high strength and low elongation, which causes cracking or splitting to occur during the cold rolling process, making it difficult to roll to the target thickness.

[0212] Accordingly, in the present invention, the FeCoV alloy-based plate is heat-treated at 600 to 1200°C for 10 to 240 minutes to change the α-ferrite phase into a γ-austenite phase, thereby changing the FeCoV alloy-based plate to form a disordered structure.

[0213] After that, by including a step of rapidly cooling the above FeCoV alloy-based sheet so that it can maintain the structure of the γ-austenite phase, the elongation is improved and the problem occurring during the cold rolling process is solved.

[0214] In another embodiment of the present invention, the rapid cooling step may be rapid cooling at a rate of 10 to 300°C / sec. Preferably, the rapid cooling may be performed at a rate of 30 to 150°C / sec, more preferably at a rate of 50 to 100°C / sec.

[0215] It is desirable that when the rate of rapid cooling satisfies the above range, the γ-austenite phase is stably maintained, allowing for the production of a FeCoV alloy-based thin sheet having a high saturation magnetic flux density.

[0216] The above rapid cooling step may involve performing water cooling or oil cooling.

[0217] The above water cooling or oil cooling method is not specifically limited in the present invention, and general methods practiced in the art may be applied. For example, it may be performed using a water or oil cooling guide and a conveyor roll, but is not limited thereto.

[0218] By performing the above water cooling or oil cooling, the γ-austenite phase structure, which is a high-temperature stable phase, can be stably maintained.

[0219] The above rapid cooling step may be performed by immersing the FeCoV-based alloy plate in cooling water.

[0221] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of cold-rolling the rapidly cooled FeCoV alloy-based sheet material to obtain a FeCoV alloy-based thin sheet.

[0222] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention allows for smooth cold rolling by heat-treating an α-ferrite phase with a regular structure according to a specific temperature range and time, and then rapidly cooling it to change it into a γ-austenite phase with an irregular structure.

[0223] The above cold rolling may be performed repeatedly while varying the reduction ratio, but is not limited thereto.

[0224] The cumulative reduction rate may be 85% or more, specifically 90% or more, and more specifically 95% or more, but is not limited to this.

[0226] A method for manufacturing a FeCoV alloy-based thin sheet according to the present invention comprises the step of stress relief heat treatment of the FeCoV alloy-based thin sheet.

[0227] By including a step of stress relief heat treatment of the above FeCoV alloy-based thin sheet, residual stress present inside the FeCoV alloy-based thin sheet after cold rolling can be removed, and regularity is ensured as the irregular γ-austenite phase changes into a stable phase, thereby making it desirable to obtain a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value, a low iron loss value, and appropriate tensile strength and elongation.

[0229] Soft magnetic FeCoV alloys undergo a process in which the phase of the microstructure changes during the manufacturing process of thin sheets, and in this process, the specific method of heat treatment, such as the heat treatment atmosphere, temperature, and time, affects the values ​​of magnetic properties, such as saturation magnetic flux density, residual magnetic flux density, coercivity, and core loss.

[0230] Here, when soft magnetic materials are used as materials for drive motor components, they exhibit characteristics where higher saturation magnetic flux density or magnetic flux density values ​​in a specific frequency range are advantageous, and lower loss values ​​such as iron loss are advantageous. Consequently, alloy design, processing, and heat treatment are carried out to achieve high magnetic flux density and low iron loss values. As a result, when the value obtained by dividing magnetic flux density by iron loss is defined as the high-efficiency value, the higher this value, the better the material is for motors.

[0231] In the present invention, heat treatment for microstructure control is performed between hot rolling and cold rolling to facilitate cold rolling, and stress relief heat treatment is performed after cold rolling to improve mechanical properties, particularly elongation and magnetic properties, thereby providing the advantage of being able to manufacture FeCoV alloy-based thin sheets with excellent mechanical and magnetic properties.

[0232] In another embodiment of the present invention, the stress relief heat treatment may be performed at 650 to 950°C for 10 to 120 minutes.

[0233] Preferably, the stress relief heat treatment may be performed at a temperature of 700 to 950°C, more preferably 850 to 950°C, but is not limited thereto.

[0235] Another aspect of the present invention relates to a method for manufacturing a FeCoV alloy-based thin sheet, comprising the steps of: preparing a FeCoV alloy-based sheet; heat-treating the FeCoV alloy-based sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated FeCoV alloy-based sheet; and cold-rolling the rapidly cooled FeCoV alloy-based sheet to obtain a FeCoV alloy-based thin sheet.

[0236] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes a step of changing at least a portion of the α-ferrite phase into a γ-austenite phase, thereby enabling easy cold rolling and having the advantage of being able to manufacture a FeCoV alloy-based thin sheet having excellent saturation magnetic flux density and low iron loss value without undergoing complex processes such as conventional forging.

[0238] A method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of preparing a FeCoV alloy-based sheet material.

[0239] The step of preparing the above-mentioned FeCoV alloy-based sheet is not limited in the present invention. For example, the above-mentioned FeCoV alloy-based sheet may be purchased from the market or manufactured directly.

[0241] In another embodiment of the present invention, the step of preparing an FeCoV alloy-based plate may include: preparing a FeCoV alloy molten metal by vacuum melting an alloy composition consisting of 20 to 49 at% cobalt, more than 0 to 5 at% vanadium, 0 to 15 at% nickel, 0 to 3 wt% chromium, 0 to 1 at% niobium, and the remainder being iron and other impurities; casting the alloy molten metal to produce an ingot; and hot rolling the ingot to obtain an FeCoV alloy-based plate.

[0242] The above other impurities may be one or more selected from the group consisting of carbon, oxygen, silicon, and manganese.

[0243] Specifically, the above-mentioned FeCoV alloy molten metal may contain alloy components composed of 30 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0244] More specifically, the above-mentioned FeCoV alloy molten metal may contain alloy components composed of 40 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0245] FeCoV-based alloys are alloy compositions with soft magnetic properties. Manufactured into thin sheets, they are primarily used in motor cores for electronic products, and recently, their application as drive motors for electric vehicles is being considered.

[0246] To increase the output of electric vehicles, the magnetic flux density of the motor core material must be high. Most recent electric vehicles have values ​​exceeding 2 Tesla, and since FeCoV alloys can reach up to 2.4 Tesla, they can be highly beneficial for improving motor core output. Furthermore, they possess significantly lower iron loss values ​​compared to other soft magnetic materials, which not only improves efficiency but also enables longer driving distances due to lower losses relative to batteries of the same capacity. For the same reasons, it is possible to miniaturize and lighten motors that exhibit the same performance.

[0247] For such FeCoV alloys, the rolling process defect rate can vary depending on the manufacturing process, even if the alloy composition is the same, and the mechanical and magnetic properties of the manufactured sheet can be significantly affected.

[0248] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of easily manufacturing a thin sheet having high mechanical and magnetic properties without including conventional complex slag removal processes, forging processes, and slab shape forming processes.

[0249] Meanwhile, the saturation magnetic flux density and coercivity values ​​of the FeCoV alloy-based thin sheet manufactured according to the composition of the above FeCoV alloy components may vary slightly.

[0250] When using FeCoV alloy components having the composition described above, there is an advantage in obtaining FeCoV alloy-based thin sheets having a high saturation magnetic flux density value and low coercivity.

[0251] The above FeCoV alloy molten metal is Fe 49 Co 49 It can have V2 composition.

[0252] By vacuum melting the above alloy components, a grayish ingot with low contamination can be obtained, and when solidified into an ingot shape through the casting step described later, it is desirable to suppress the phenomenon in which an ingot with an uneven composition is obtained due to compositional inconsistency, such as when the composition of the upper and middle parts or the middle and lower parts of the ingot differs, or when segregation exists in the same part. In addition, it is desirable to suppress the phenomenon in which cracks are induced during hot rolling, cold rolling, etc., due to the oxide layer being too thick.

[0254] The step of preparing the molten alloy may be performed under an argon, nitrogen, or carbon dioxide atmosphere. It is preferable that the step of preparing the molten alloy be performed under an argon, nitrogen, or carbon dioxide atmosphere, as this can suppress the oxidation or carbonization of the alloy components.

[0256] In the step of preparing a molten FeCoV alloy by vacuum melting the above alloy components, the vacuum level is 1×10 -2 Up to 1×10 -4 torr, preferably 1×10 -2 Up to 1×10 -3 It could be torr.

[0257] If the above vacuum level satisfies the above range, it is desirable to be able to suppress oxidation or carbonization.

[0259] The method may further include, but is not limited to, a step of removing slag from the molten alloy liquid prior to casting the molten alloy.

[0260] Alternatively, the step of removing slag from the molten alloy liquid before casting the molten alloy may not be included, but is not limited thereto.

[0261] The method of manufacturing an ingot by casting the above-mentioned molten alloy is not specifically limited in the present invention.

[0262] For example, the molten alloy can be poured into a mold and cooled and crystallized to produce an ingot.

[0263] It is preferable that the injection temperature be 100 to 2000°C, preferably 100 to 1000°C, and more preferably 200 to 500°C higher than the liquid phase temperature of the molten metal. The liquid phase temperature of the molten metal can be measured using a direct temperature measurement method with a built-in thermocouple or by using a non-contact laser thermometer on the surface of the molten metal.

[0264] In addition, the cooling temperature and speed can be controlled to ensure uniformity of composition and prevent segregation. Since the upper part of the ingot cools relatively quickly while the lower part or interior cools slowly, the parts that cool quickly can be heated, or they can be insulated with non-metallic ceramics or slag.

[0266] The above ingot may be manufactured in the shape of, for example, a bar, a polyhedron, a cylinder, a sphere, or an irregular shape, but is not limited thereto.

[0267] The step of preparing the above FeCoV alloy-based plate may further include the step of cutting the above ingot into 4 to 30 mm pieces.

[0268] For example, the method for manufacturing the above FeCoV alloy-based thin sheet may further include a step of cutting the ingot into 10 to 30 mm. It is desirable to further include a step of cutting the ingot within the above range so that hot rolling is smooth.

[0269] The cutting of the above ingot may be carried out by methods conventionally performed in the art, and the present invention is not limited thereto.

[0271] The method may further include the step of manufacturing an ingot by casting the above-mentioned molten alloy; and the step of homogenizing the ingot thereafter.

[0272] The above homogenization heat treatment may be performed at 1200 to 1300°C for 1 to 12 hours.

[0273] Preferably, the homogenization heat treatment may be performed for 2 to 6 hours, more preferably for 2 to 4 hours, but is not limited thereto.

[0274] It is desirable to further include the above homogenization heat treatment step so that stress generated during casting can be relieved.

[0276] The step of preparing the above FeCoV alloy-based plate may include the step of obtaining a plate by hot rolling the above ingot.

[0277] It is desirable to obtain a plate in which the γ-austenite phase formed by slow cooling accounts for the majority, or in which the α-ferrite phase and the γ-austenite phase are mixed by hot rolling the above ingot.

[0279] The above hot rolling can be performed, for example, using a steel rolling mill.

[0280] The above rolling start temperature, rolling speed, rolling end temperature, etc., are not specifically limited in the present invention and can be appropriately performed under ordinary conditions practiced in the industry.

[0281] For example, the starting temperature for the above rolling may be 900°C or higher and may not exceed 1300°C. When the starting temperature for the above rolling satisfies the above range, it is desirable as there is an advantage of excellent strength and formability of the sheet material being manufactured.

[0282] The above rolling end temperature may be 1150℃ or higher. When the above rolling end temperature is 1150℃ or higher, it is desirable because it can suppress the phenomenon of strain on the equipment due to high deformation resistance and facilitate shape control.

[0284] The total reduction rate by the above hot rolling may be 70 to 90%, preferably 75 to 90%, and more preferably 75 to 85%. When the total reduction rate satisfies the above range, it is desirable to suppress the increase of crystal grains caused by high energy and to reduce the deviation thereof.

[0286] The above rolling may be performed in one to several passes, but is not limited thereto.

[0287] In another embodiment of the present invention, the rolling may be performed in two or more rolling passes. Specifically, the rolling may be performed in five or more rolling passes, but is not limited thereto.

[0289] If the temperature decreases as the above hot rolling is repeated, it is desirable to raise the temperature by reheating and then perform hot rolling. It is desirable to control the lower limit of the temperature during the rolling process to 900°C or higher, preferably 900 to 1000°C.

[0290] When the lower limit of the temperature during the above rolling process satisfies the above range, it is desirable because it exists mostly in the γ-austenite phase, so cracks and bursting hardly occur during hot rolling and it becomes smooth.

[0292] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of heat-treating the sheet material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase.

[0293] Although I do not wish to be limited by theory, generally, FeCoV-based alloys undergo phase changes as they go through casting, hot rolling, heat treatment, and cold rolling processes, and even within the same phase, they change into regular and irregular lattices.

[0294] For example, when a FeCoV-based alloy is melted in a vacuum and cast into an ingot, an α-ferrite phase is formed.

[0295] In the case of α-ferrite, which is a microstructure at room temperature, it has a body-centered cubic (BCC) structure and relatively few slip planes, so there is a high possibility that cold rolling will not be performed smoothly when using FeCoV alloy-based sheet materials to make thin sheets.

[0296] In particular, due to residual stress present within the sheet metal after cold rolling, forming becomes difficult and soft magnetic properties may not be properly realized.

[0297] On the other hand, the γ-austenite structure, which is a high-temperature structure, has an irregular face-centered cubic (FCC) structure and has many slip planes, making it easy to roll, and thus its plastic workability is much better than that of α-ferrite.

[0298] Accordingly, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention involves heat-treating the sheet material at a temperature of 600 to 1200°C, which is a high-temperature stable phase region, so that it has a γ-austenite structure, which is a high-temperature stable phase, in other words, an FCC structure, and then rapidly cooling it, thereby changing the α-ferrite phase generated through the casting process and hot rolling process into a γ-austenite phase, so that it has a γ-austenite phase or a structure having a composite structure of an α-ferrite phase and a γ-austenite phase.

[0299] In another embodiment of the present invention, the heat treatment may be performed at a temperature of 730 to 1200°C. Specifically, the heat treatment may be performed at a temperature of 730°C or higher, which is the temperature at which ordering of irregular / ordered lattice structures begins, and at a temperature of 1200°C or lower, which is the temperature at which atomic structure changes are expected to be most active without the formation of a liquid phase. Specifically, it is preferable that the heat treatment be performed within the above range, which is the temperature region where irregular / ordered structural changes occur.

[0301] In another embodiment of the present invention, the heat treatment may be performed at 840 to 1200°C.

[0302] Specifically, the above heat treatment can be performed at a temperature of 840°C or higher, which is the temperature at which phase transformation occurs, and at a temperature of 1200°C or lower, which is the temperature at which solid phase control is possible without the presence of a liquid phase.

[0303] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be heat treatment at 850 to 950°C.

[0304] Since FeCoV alloy-based sheet materials can vary significantly in mechanical and / or magnetic properties depending on the heat treatment temperature even with the same composition, the present invention allows for obtaining a FeCoV alloy-based thin sheet with excellent mechanical properties and superior magnetic properties—that is, having high saturation magnetic flux density and low iron loss values ​​simultaneously—by heat treating at a temperature within the above range.

[0306] In another embodiment of the present invention, the heat treatment may be performed for 30 to 240 minutes.

[0307] Preferably, the heat treatment can be performed for 60 to 120 minutes.

[0308] When the above heat treatment time satisfies the above range, it is desirable because the phase transformation time to the γ-austenite phase is sufficient while shortening the heat treatment time.

[0309] In short, the step of changing to the γ-austenite phase may be heat treatment at a temperature of 850 to 950°C for 60 to 120 minutes.

[0311] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be performed under a vacuum or an inert gas atmosphere. Since the FeCoV-based alloy is somewhat prone to oxidation, it is preferable to perform the step of changing to the γ-austenite phase under a vacuum or an inert gas atmosphere.

[0312] The above inert gas may be, for example, high-purity argon (Ar) gas, but is not limited thereto.

[0314] In another embodiment of the present invention, a step of removing surface scale from the plate material may be further included prior to the step of heat-treating the plate material.

[0315] An oxide scale may form on the surface of the hot-rolled sheet metal. Since the oxide scale can affect the quality of the sheet metal, it is desirable to further include a step of removing the surface scale from the sheet metal.

[0316] The method for removing surface scale from the above-mentioned plate can be performed using conventional methods practiced in the industry.

[0317] For example, the above-mentioned plate may be immersed in a hydrochloric acid bath to perform pickling treatment, or a slurry mixed with high-pressure water and abrasive may be sprayed at high pressure onto the above-mentioned plate to remove the surface scale, but is not limited thereto.

[0319] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of quenching the heat-treated FeCoV alloy-based sheet material.

[0320] In the cold rolling process described later, if the microstructure of the above FeCoV alloy-based sheet material forms an regular structure, it has high strength and low elongation, which causes cracking or splitting to occur during the cold rolling process, making it difficult to roll to the target thickness.

[0321] Accordingly, in the present invention, the FeCoV alloy-based plate is heat-treated at 600 to 1200°C for 10 to 240 minutes to change the α-ferrite phase into a γ-austenite phase, thereby changing the FeCoV alloy-based plate to form a disordered structure.

[0322] After that, by including a step of rapidly cooling the above FeCoV alloy-based sheet so that it can maintain the structure of the γ-austenite phase, the elongation is improved and the problem occurring during the cold rolling process is solved.

[0323] In another embodiment of the present invention, the rapid cooling step may be rapid cooling at a rate of 10 to 300°C / sec. Preferably, the rapid cooling may be performed at a rate of 30 to 150°C / sec, more preferably at a rate of 50 to 100°C / sec.

[0324] It is desirable that when the rate of rapid cooling satisfies the above range, the γ-austenite phase is stably maintained, allowing for the production of a FeCoV alloy-based thin sheet having a high saturation magnetic flux density.

[0325] The above rapid cooling step may involve performing water cooling or oil cooling.

[0326] The above water cooling or oil cooling method is not specifically limited in the present invention, and general methods practiced in the art may be applied. For example, it may be performed using a water or oil cooling guide and a conveyor roll, but is not limited thereto.

[0327] By performing the above water cooling or oil cooling, the γ-austenite phase structure, which is a high-temperature stable phase, can be stably maintained.

[0328] The above rapid cooling step may be performed by immersing the FeCoV-based alloy plate in cooling water.

[0330] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of cold-rolling the rapidly cooled FeCoV alloy-based sheet material to obtain a FeCoV alloy-based thin sheet.

[0331] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention allows for smooth cold rolling by heat-treating an α-ferrite phase with a regular structure according to a specific temperature range and time, and then rapidly cooling it to change it into a γ-austenite phase with an irregular structure.

[0332] The above cold rolling may be performed repeatedly while varying the reduction ratio, but is not limited thereto.

[0333] The cumulative reduction rate may be 85% or more, specifically 90% or more, and more specifically 95% or more, but is not limited to this.

[0335] In another embodiment of the present invention, the method may further include the step of obtaining the FeCoV alloy-based thin sheet; and subsequently the step of performing stress relief heat treatment on the FeCoV alloy-based thin sheet.

[0336] By including a step of stress relief heat treatment of the above FeCoV alloy-based thin sheet, residual stress present inside the FeCoV alloy-based thin sheet after cold rolling can be removed, and regularity is ensured as the irregular γ-austenite phase changes into a stable phase, thereby making it desirable to obtain a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value, a low iron loss value, and appropriate tensile strength and elongation.

[0338] Soft magnetic FeCoV alloys undergo a process in which the phase of the microstructure changes during the manufacturing process of thin sheets, and in this process, the specific method of heat treatment, such as the heat treatment atmosphere, temperature, and time, affects the values ​​of magnetic properties, such as saturation magnetic flux density, residual magnetic flux density, coercivity, and core loss.

[0339] Here, when soft magnetic materials are used as materials for drive motor components, they exhibit characteristics where higher saturation magnetic flux density or magnetic flux density values ​​in a specific frequency range are advantageous, and lower loss values ​​such as iron loss are advantageous. Consequently, alloy design, processing, and heat treatment are carried out to achieve high magnetic flux density and low iron loss values. As a result, when the value obtained by dividing magnetic flux density by iron loss is defined as the high-efficiency value, the higher this value, the better the material is for motors.

[0340] In the present invention, heat treatment for microstructure control is performed between hot rolling and cold rolling to facilitate cold rolling, and additional stress relief heat treatment is performed after cold rolling to improve mechanical properties, particularly elongation and magnetic properties, thereby providing the advantage of being able to manufacture FeCoV alloy-based thin sheets with excellent mechanical and magnetic properties.

[0341] In another embodiment of the present invention, the stress relief heat treatment may be performed at 650 to 950°C for 10 to 120 minutes.

[0342] Preferably, the stress relief heat treatment may be performed at a temperature of 700 to 950°C, more preferably 850 to 950°C, but is not limited thereto.

[0344] Another aspect of the present invention relates to a method for manufacturing a FeCoV alloy-based thin sheet, comprising the steps of: preparing a FeCoV alloy molten metal; casting the alloy molten metal to produce an ingot; hot rolling the ingot to obtain a sheet; heat treating the sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated sheet; and cold rolling the rapidly cooled sheet to obtain a FeCoV alloy-based thin sheet; wherein the FeCoV alloy-based thin sheet is such that the intensity of the peak of the (100) plane among the peaks of the X-ray diffraction pattern of the ingot is reduced or does not appear.

[0345] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes a step of changing at least a portion of the α-ferrite phase into a γ-austenite phase, thereby enabling easy cold rolling and having the advantage of being able to manufacture a FeCoV alloy-based thin sheet having excellent saturation magnetic flux density and low iron loss value without undergoing complex processes such as conventional forging.

[0346] In another embodiment of the present invention, the step of preparing the alloy melt may include the step of vacuum melting an alloy component composed of 20 to 49 at% cobalt, 2 to 5 at% vanadium, and the remainder being iron and other impurities.

[0347] The above other impurities may be one or more selected from the group consisting of carbon, oxygen, silicon, and manganese.

[0348] In another embodiment of the present invention, the FeCoV alloy molten metal may comprise an alloy composition consisting of 30 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0349] In another embodiment of the present invention, the FeCoV alloy molten metal may comprise an alloy composition consisting of 40 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0350] FeCoV-based alloys are alloy compositions with soft magnetic properties. Manufactured into thin sheets, they are primarily used in motor cores for electronic products, and recently, their application as drive motors for electric vehicles is being considered.

[0351] To increase the output of electric vehicles, the magnetic flux density of the motor core material must be high. Most recent electric vehicles have values ​​exceeding 2 Tesla, and since FeCoV alloys can reach up to 2.4 Tesla, they can be highly beneficial for improving motor core output. Furthermore, they possess significantly lower iron loss values ​​compared to other soft magnetic materials, which not only improves efficiency but also enables longer driving distances due to lower losses relative to batteries of the same capacity. For the same reasons, it is possible to miniaturize and lighten motors that exhibit the same performance.

[0352] For such FeCoV alloys, the rolling process defect rate can vary depending on the manufacturing process, even if the alloy composition is the same, and the mechanical and magnetic properties of the manufactured sheet can be significantly affected.

[0353] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of easily manufacturing a thin sheet having high mechanical and magnetic properties without including conventional complex slag removal processes, forging processes, and slab shape forming processes.

[0354] Meanwhile, the saturation magnetic flux density and coercivity values ​​of the FeCoV alloy-based thin sheet manufactured according to the composition of the above FeCoV alloy components may vary slightly.

[0355] In the present invention, by using an FeCoV alloy component having the composition described above, there is an advantage in obtaining a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value and low coercivity.

[0356] The above FeCoV alloy molten metal is Fe 49 Co 49 It can have V2 composition.

[0357] By vacuum melting the above alloy components, a grayish ingot with low contamination can be obtained, and when solidified into an ingot shape through the casting step described later, it is desirable to suppress the phenomenon in which an ingot with an uneven composition is obtained due to compositional inconsistency, such as when the composition of the upper and middle parts or the middle and lower parts of the ingot differs, or when segregation exists in the same part. In addition, it is desirable to suppress the phenomenon in which cracks are induced during hot rolling, cold rolling, etc., due to the oxide layer being too thick.

[0359] The step of preparing the molten alloy may be performed under an argon, nitrogen, or carbon dioxide atmosphere. It is preferable that the step of preparing the molten alloy be performed under an argon, nitrogen, or carbon dioxide atmosphere, as this can suppress the oxidation or carbonization of the alloy components.

[0361] In the step of preparing a molten FeCoV alloy by vacuum melting the above alloy components, the vacuum level is 1×10 -2 Up to 1×10 -4 torr, preferably 1×10 -2 Up to 1×10 -3 It could be torr.

[0362] If the above vacuum level satisfies the above range, it is desirable to be able to suppress oxidation or carbonization.

[0364] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of manufacturing an ingot by casting the molten alloy.

[0365] The method may further include, but is not limited to, a step of removing slag from the molten alloy liquid prior to casting the molten alloy.

[0366] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may not include a step of removing slag from the molten alloy. Specifically, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of being able to manufacture a FeCoV alloy-based thin sheet exhibiting excellent performance without including a slag removal process, a forging process, or a shape-controlled sraving process.

[0367] The method of manufacturing an ingot by casting the above-mentioned molten alloy is not specifically limited in the present invention.

[0368] For example, the molten alloy can be poured into a mold and cooled and crystallized to produce an ingot.

[0369] It is preferable that the injection temperature be 100 to 2000°C, preferably 100 to 1000°C, and more preferably 200 to 500°C higher than the liquid phase temperature of the molten metal. The liquid phase temperature of the molten metal can be measured using a direct temperature measurement method with a built-in thermocouple or by using a non-contact laser thermometer on the surface of the molten metal.

[0370] In addition, the cooling temperature and speed can be controlled to ensure uniformity of composition and prevent segregation. Since the upper part of the ingot cools relatively quickly while the lower part or interior cools slowly, the parts that cool quickly can be heated, or they can be insulated with non-metallic ceramics or slag.

[0372] The above ingot may be manufactured in the shape of, for example, a bar, a polyhedron, a cylinder, a sphere, or an irregular shape, but is not limited thereto.

[0373] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may further include the step of cutting the ingot into 4 to 30 mm.

[0374] For example, the method for manufacturing the above FeCoV alloy-based thin sheet may further include a step of cutting the ingot into 10 to 30 mm. It is desirable to further include a step of cutting the ingot within the above range so that hot rolling is smooth.

[0375] The cutting of the above ingot may be carried out by methods conventionally performed in the art, and the present invention is not limited thereto.

[0377] In another embodiment of the present invention, the method may further include the step of manufacturing an ingot by casting the molten alloy; and the step of homogenizing the ingot thereafter.

[0378] In another embodiment of the present invention, the homogenization heat treatment may be performed at 1200 to 1300°C for 1 to 12 hours.

[0379] Preferably, the homogenization heat treatment may be performed for 2 to 6 hours, more preferably for 2 to 4 hours, but is not limited thereto.

[0380] It is desirable to further include the above homogenization heat treatment step so that stress generated during casting can be relieved.

[0382] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of hot rolling the ingot to obtain a sheet material.

[0383] It is desirable to obtain a plate in which the γ-austenite phase formed by slow cooling accounts for the majority, or in which the α-ferrite phase and the γ-austenite phase are mixed by hot rolling the above ingot.

[0385] The above hot rolling can be performed, for example, using a steel rolling mill.

[0386] The above rolling start temperature, rolling speed, rolling end temperature, etc., are not specifically limited in the present invention and can be appropriately performed under ordinary conditions practiced in the industry.

[0387] For example, the starting temperature for the above rolling may be 900°C or higher and may not exceed 1300°C. When the starting temperature for the above rolling satisfies the above range, it is desirable as there is an advantage of excellent strength and formability of the sheet material being manufactured.

[0388] The above rolling end temperature may be 1150℃ or higher. When the above rolling end temperature is 1150℃ or higher, it is desirable because it can suppress the phenomenon of strain on the equipment due to high deformation resistance and facilitate shape control.

[0390] The total reduction rate by the above hot rolling may be 70 to 90%, preferably 75 to 90%, and more preferably 75 to 85%. When the total reduction rate satisfies the above range, it is desirable to suppress the increase of crystal grains caused by high energy and to reduce the deviation thereof.

[0392] The above rolling may be performed in one to several passes, but is not limited thereto.

[0393] In another embodiment of the present invention, the rolling may be performed in two or more rolling passes. Specifically, the rolling may be performed in five or more rolling passes, but is not limited thereto.

[0395] If the temperature decreases as the above hot rolling is repeated, it is desirable to raise the temperature by reheating and then perform hot rolling. It is desirable to control the lower limit of the temperature during the rolling process to 900°C or higher, preferably 900 to 1000°C.

[0396] When the lower limit of the temperature during the above rolling process satisfies the above range, it is desirable because it exists mostly in the γ-austenite phase, so cracks and bursting hardly occur during hot rolling and it becomes smooth.

[0398] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of heat-treating the sheet material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase.

[0399] Although I do not wish to be limited by theory, generally, FeCoV-based alloys undergo phase changes as they go through casting, hot rolling, heat treatment, and cold rolling processes, and even within the same phase, they change into regular and irregular lattices.

[0400] For example, when a FeCoV-based alloy is melted in a vacuum and cast into an ingot, an α-ferrite phase is formed.

[0401] In the case of α-ferrite, which is a microstructure at room temperature, it has a body-centered cubic (BCC) structure and relatively few slip planes, so there is a high possibility that cold rolling will not be performed smoothly when using FeCoV alloy-based sheet materials to make thin sheets.

[0402] In particular, due to residual stress present within the sheet metal after cold rolling, forming becomes difficult and soft magnetic properties may not be properly realized.

[0403] On the other hand, the γ-austenite structure, which is a high-temperature structure, has an irregular face-centered cubic (FCC) structure and has many slip planes, making it easy to roll, and thus its plastic workability is much better than that of α-ferrite.

[0404] Accordingly, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention involves heat-treating the sheet material at a temperature of 600 to 1200°C, which is a high-temperature stable phase region, so that it has a γ-austenite structure, which is a high-temperature stable phase, in other words, an FCC structure, and then rapidly cooling it, thereby changing the α-ferrite phase generated through the casting process and hot rolling process into a γ-austenite phase, so that it has a γ-austenite phase or a structure having a composite structure of an α-ferrite phase and a γ-austenite phase.

[0405] In another embodiment of the present invention, the heat treatment may be performed at a temperature of 730 to 1200°C. Specifically, the heat treatment may be performed at a temperature of 730°C or higher, which is the temperature at which ordering of irregular / ordered lattice structures begins, and at a temperature of 1200°C or lower, which is the temperature at which atomic structure changes are expected to be most active without the formation of a liquid phase. Specifically, it is preferable that the heat treatment be performed within the above range, which is the temperature region where irregular / ordered structural changes occur.

[0407] In another embodiment of the present invention, the heat treatment may be performed at 840 to 1200°C.

[0408] Specifically, the above heat treatment can be performed at a temperature of 840°C or higher, which is the temperature at which phase transformation occurs, and at a temperature of 1200°C or lower, which is the temperature at which solid phase control is possible without the presence of a liquid phase.

[0409] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be heat treatment at 850 to 950°C.

[0410] Since FeCoV alloy-based sheet materials can vary significantly in mechanical and / or magnetic properties depending on the heat treatment temperature even with the same composition, the present invention allows for obtaining a FeCoV alloy-based thin sheet with excellent mechanical properties and superior magnetic properties—that is, having high saturation magnetic flux density and low iron loss values ​​simultaneously—by heat treating at a temperature within the above range.

[0412] In another embodiment of the present invention, the heat treatment may be performed for 30 to 240 minutes.

[0413] Preferably, the heat treatment can be performed for 60 to 120 minutes.

[0414] When the above heat treatment time satisfies the above range, it is desirable because the phase transformation time to the γ-austenite phase is sufficient while shortening the heat treatment time.

[0415] In short, the step of changing to the γ-austenite phase may be heat treatment at a temperature of 850 to 950°C for 60 to 120 minutes.

[0417] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be performed under a vacuum or an inert gas atmosphere. Since the FeCoV-based alloy is somewhat prone to oxidation, it is preferable to perform the step of changing to the γ-austenite phase under a vacuum or an inert gas atmosphere.

[0418] The above inert gas may be, for example, high-purity argon (Ar) gas, but is not limited thereto.

[0420] In another embodiment of the present invention, a step of removing surface scale from the plate material may be further included prior to the step of heat-treating the plate material.

[0421] An oxide scale may form on the surface of the hot-rolled sheet metal. Since the oxide scale can affect the quality of the sheet metal, it is desirable to further include a step of removing the surface scale from the sheet metal.

[0422] The method for removing surface scale from the above-mentioned plate can be performed using conventional methods practiced in the industry.

[0423] For example, the above-mentioned plate may be immersed in a hydrochloric acid bath to perform pickling treatment, or a slurry mixed with high-pressure water and abrasive may be sprayed at high pressure onto the above-mentioned plate to remove the surface scale, but is not limited thereto.

[0425] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of quenching the heat-treated FeCoV alloy-based sheet material.

[0426] In the cold rolling process described later, if the microstructure of the above FeCoV alloy-based sheet material forms an regular structure, it has high strength and low elongation, which causes cracking or splitting to occur during the cold rolling process, making it difficult to roll to the target thickness.

[0427] Accordingly, in the present invention, the FeCoV alloy-based plate is heat-treated at 600 to 1200°C for 10 to 240 minutes to change the α-ferrite phase into a γ-austenite phase, thereby changing the FeCoV alloy-based plate to form a disordered structure.

[0428] After that, by including a step of rapidly cooling the above FeCoV alloy-based sheet so that it can maintain the structure of the γ-austenite phase, the elongation is improved and the problem occurring during the cold rolling process is solved.

[0429] In another embodiment of the present invention, the rapid cooling step may be rapid cooling at a rate of 10 to 300°C / sec. Preferably, the rapid cooling may be performed at a rate of 30 to 150°C / sec, more preferably at a rate of 50 to 100°C / sec.

[0430] It is desirable that when the rate of rapid cooling satisfies the above range, the γ-austenite phase is stably maintained, allowing for the production of a FeCoV alloy-based thin sheet having a high saturation magnetic flux density.

[0431] The above rapid cooling step may involve performing water cooling or oil cooling.

[0432] The above water cooling or oil cooling method is not specifically limited in the present invention, and general methods practiced in the art may be applied. For example, it may be performed using a water or oil cooling guide and a conveyor roll, but is not limited thereto.

[0433] By performing the above water cooling or oil cooling, the γ-austenite phase structure, which is a high-temperature stable phase, can be stably maintained.

[0434] The above rapid cooling step may be performed by immersing the FeCoV-based alloy plate in cooling water.

[0436] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of cold-rolling the rapidly cooled FeCoV alloy-based sheet material to obtain a FeCoV alloy-based thin sheet.

[0437] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention allows for smooth cold rolling by heat-treating an α-ferrite phase with a regular structure according to a specific temperature range and time, and then rapidly cooling it to change it into a γ-austenite phase with an irregular structure.

[0438] The above cold rolling may be performed repeatedly while varying the reduction ratio, but is not limited thereto.

[0439] The cumulative reduction rate may be 85% or more, specifically 90% or more, and more specifically 95% or more, but is not limited to this.

[0441] In the FeCoV alloy-based thin sheet according to the present invention, the intensity of the peak of the (100) plane among the peaks of the X-ray diffraction pattern of the ingot is reduced or does not appear.

[0442] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have an increased intensity of the peak of the (211) plane among the peaks of the X-ray diffraction pattern of the ingot.

[0443] In the case of the above ingot, because it exhibits an ordered structure due to slow cooling, the peak of the (100) plane appears highest in the X-ray diffraction pattern, while the others show peaks of relatively very low intensity. However, if heat treatment is performed to remove the stress generated during the rolling process after the final cold rolling, the intensity of the peak of the (100) plane of the above ingot decreases or does not appear.

[0444] On the other hand, as the irregular structure changes into a regular structure depending on the heat treatment, the intensity of the (211) plane peak among the peaks of the X-ray diffraction pattern of the ingot may increase.

[0446] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a reduced intensity of the peak of the (100) plane among the peaks of the X-ray diffraction pattern of the hot-rolled sheet material, or may not appear.

[0447] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have an increased intensity of the peak of the (211) plane among the peaks of the hot-rolled X-ray diffraction pattern.

[0449] The above FeCoV alloy-based thin sheet may have different full widths at half maximum peaks in the range of 2θ to 42 to 47° in the X-ray diffraction chart obtained by XRD analysis before and after heat treatment of the sheet.

[0450] The above FeCoV alloy-based thin sheet may have different maximum peak full widths in the range of 2θ to 42 to 47° in the X-ray diffraction chart obtained by XRD analysis before and after stress relief heat treatment of the above FeCoV alloy-based thin sheet.

[0452] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may contain crystal grains of 150 μm or less in an amount of 50% or more compared to the ingot.

[0453] The above FeCoV alloy-based thin sheet retains a portion of the high-temperature structure by performing heat treatment at the high temperature and then rapidly cooling it. Therefore, at least some or all of the α-ferrite phase is transformed into the γ-austenite phase through heat treatment, and because it is manufactured through processes such as repetitive cold rolling, it may contain 50% or more, specifically 60% or more, and more specifically 70% or more of relatively uniform grains of 150 μm or less compared to the above ingot.

[0454] In another embodiment of the present invention, the difference between the area occupied by cobalt and the area occupied by iron within the region up to 35 μm from the surface of the FeCoV alloy-based thin sheet on the GDS depth profile may be smaller than the difference between the area occupied by cobalt and the area occupied by iron within the region up to 35 μm from the surface of the hot-rolled sheet.

[0455] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have less impurity content in the region up to 5 μm from the surface of the FeCoV alloy-based thin sheet on the GDS depth profile than the impurity content in the region up to 5 μm from the surface of the hot-rolled sheet material.

[0456] The above impurities may refer to oxides or carbides generated by oxygen (O2), carbon (C), etc.

[0457] Specifically, the FeCoV alloy-based thin sheet according to the present invention has excellent mechanical properties as well as magnetic properties, as the impurity content, such as oxygen and carbon, is rapidly reduced within a region of up to 5 μm from the surface of the thin sheet, and oxides and carbides are not present inside.

[0459] In another embodiment of the present invention, the method may further include the step of obtaining the FeCoV alloy-based thin sheet; and subsequently the step of performing stress relief heat treatment on the FeCoV alloy-based thin sheet.

[0460] By including a step of stress relief heat treatment of the above FeCoV alloy-based thin sheet, residual stress present inside the FeCoV alloy-based thin sheet after cold rolling can be removed, and regularity is ensured as the irregular γ-austenite phase changes into a stable phase, thereby making it desirable to obtain a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value, a low iron loss value, and appropriate tensile strength and elongation.

[0462] Soft magnetic FeCoV alloys undergo a process in which the phase of the microstructure changes during the manufacturing process of thin sheets, and in this process, the specific method of heat treatment, such as the heat treatment atmosphere, temperature, and time, affects the values ​​of magnetic properties, such as saturation magnetic flux density, residual magnetic flux density, coercivity, and core loss.

[0463] Here, when soft magnetic materials are used as materials for drive motor components, they exhibit characteristics where higher saturation magnetic flux density or magnetic flux density values ​​in a specific frequency range are advantageous, and lower loss values ​​such as iron loss are advantageous. Consequently, alloy design, processing, and heat treatment are carried out to achieve high magnetic flux density and low iron loss values. As a result, when the value obtained by dividing magnetic flux density by iron loss is defined as the high-efficiency value, the higher this value, the better the material is for motors.

[0464] In the present invention, heat treatment for microstructure control is performed between hot rolling and cold rolling to facilitate cold rolling, and additional stress relief heat treatment is performed after cold rolling to improve mechanical properties, particularly elongation and magnetic properties, thereby providing the advantage of being able to manufacture FeCoV alloy-based thin sheets with excellent mechanical and magnetic properties.

[0465] In another embodiment of the present invention, the stress relief heat treatment may be performed at 650 to 950°C for 10 to 120 minutes.

[0466] Preferably, the stress relief heat treatment may be performed at a temperature of 700 to 950°C, more preferably 850 to 950°C, but is not limited thereto.

[0468] Another aspect of the present invention relates to a method for manufacturing a FeCoV alloy-based thin sheet, comprising the steps of: preparing a FeCoV alloy molten metal by vacuum melting an alloy composition comprising 49 to 66 at% (atomic percent) of iron, 20 to 49 at% of cobalt, more than 0 and less than or equal to 2 at% of vanadium, 0 to 15 at% of nickel, 0 to 3 at% of chromium, and 0 to 1 at% of niobium; casting the alloy molten metal to produce an ingot; hot rolling the ingot to obtain a sheet; heat treating the sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated sheet; and cold rolling the rapidly cooled sheet to obtain a FeCoV alloy-based thin sheet.

[0469] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes a step of changing at least a portion of the α-ferrite phase into a γ-austenite phase, thereby enabling easy cold rolling and having the advantage of being able to manufacture a FeCoV alloy-based thin sheet having excellent saturation magnetic flux density and low iron loss value without undergoing complex processes such as conventional forging.

[0471] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention comprises the step of preparing a FeCoV alloy molten metal by vacuum melting an alloy component comprising 49 to 66 at% (atomic percent) of iron, 20 to 49 at% of cobalt, more than 0 and less than or equal to 2 at% of vanadium, 0 to 15 at% of nickel, 0 to 3 at% of chromium, and 0 to 1 at% of niobium.

[0472] The above other impurities may be one or more selected from the group consisting of carbon, oxygen, silicon, and manganese.

[0473] By preparing a molten FeCoV alloy by vacuum melting an alloy component having the above composition, it is possible to secure high saturation magnetic flux density values ​​while simultaneously obtaining mechanical properties such as strength and elongation, and there is an advantage of reducing alloy costs.

[0475] FeCoV-based alloys are alloy compositions with soft magnetic properties. Manufactured into thin sheets, they are primarily used in motor cores for electronic products, and recently, their application as drive motors for electric vehicles is being considered.

[0476] To increase the output of electric vehicles, the magnetic flux density of the motor core material must be high. Most recent electric vehicles have values ​​exceeding 2 Tesla, and since FeCoV alloys can reach up to 2.4 Tesla, they can be highly beneficial for improving motor core output. Furthermore, they possess significantly lower iron loss values ​​compared to other soft magnetic materials, which not only improves efficiency but also enables longer driving distances due to lower losses relative to batteries of the same capacity. For the same reasons, it is possible to miniaturize and lighten motors that exhibit the same performance.

[0477] For such FeCoV alloys, the rolling process defect rate can vary depending on the manufacturing process, even if the alloy composition is the same, and the mechanical and magnetic properties of the manufactured sheet can be significantly affected.

[0478] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of easily manufacturing a thin sheet having high mechanical and magnetic properties without including conventional complex slag removal processes, forging processes, and slab shape forming processes.

[0479] Meanwhile, the saturation magnetic flux density and coercivity values ​​of the FeCoV alloy-based thin sheet manufactured according to the composition of the above FeCoV alloy components may vary slightly.

[0480] In the present invention, by using an FeCoV alloy component having the composition described above, there is an advantage in obtaining a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value and low coercivity.

[0481] By vacuum melting the above alloy components, a grayish ingot with low contamination can be obtained, and when solidified into an ingot shape through the casting step described later, it is desirable to suppress the phenomenon in which an ingot with an uneven composition is obtained due to compositional inconsistency, such as when the composition of the upper and middle parts or the middle and lower parts of the ingot differs, or when segregation exists in the same part. In addition, it is desirable to suppress the phenomenon in which cracks are induced during hot rolling, cold rolling, etc., due to the oxide layer being too thick.

[0483] The step of preparing the molten alloy may be performed under an argon, nitrogen, or carbon dioxide atmosphere. It is preferable that the step of preparing the molten alloy be performed under an argon, nitrogen, or carbon dioxide atmosphere, as this can suppress the oxidation or carbonization of the alloy components.

[0485] In the step of preparing a molten FeCoV alloy by vacuum melting the above alloy components, the vacuum level is 1×10 -2 Up to 1×10 -4 torr, preferably 1×10 -2 Up to 1×10 -3 It could be torr.

[0486] If the above vacuum level satisfies the above range, it is desirable to be able to suppress oxidation or carbonization.

[0487] In the step of preparing the above-mentioned molten alloy, for elements with a large difference in melting points among the alloy components, high-melting-point metals such as Fe, Co, and V may be added first to melt them, and then low-melting-point metals such as Al and Mg may be added later, followed by cooling as described below, but is not limited thereto. However, in this case, it is desirable to suppress the phenomenon where the low-melting-point metal is exposed to high temperatures for a long time, thereby preventing the generation of fumes or vaporization.

[0488] In addition, if it is desired to add the low-melting-point metal to the high-melting-point metal in a specific amount, the target composition may be achieved by predicting the content loss and adding it in an amount slightly higher than the target composition, but is not limited thereto.

[0490] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of manufacturing an ingot by casting the molten alloy.

[0491] The method may further include, but is not limited to, a step of removing slag from the molten alloy liquid prior to casting the molten alloy.

[0492] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may not include a step of removing slag from the molten alloy. Specifically, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of being able to manufacture a FeCoV alloy-based thin sheet exhibiting excellent performance without including a slag removal process, a forging process, or a shape-controlled sraving process.

[0493] The method of manufacturing an ingot by casting the above-mentioned molten alloy is not specifically limited in the present invention.

[0494] For example, the molten alloy can be poured into a mold and cooled and crystallized to produce an ingot.

[0495] It is preferable that the injection temperature be 100 to 2000°C, preferably 100 to 1000°C, and more preferably 200 to 500°C higher than the liquid phase temperature of the molten metal. The liquid phase temperature of the molten metal can be measured using a direct temperature measurement method with a built-in thermocouple or by using a non-contact laser thermometer on the surface of the molten metal.

[0496] In addition, the cooling temperature and speed can be controlled to ensure uniformity of composition and prevent segregation. Since the upper part of the ingot cools relatively quickly while the lower part or interior cools slowly, the parts that cool quickly can be heated, or they can be insulated with non-metallic ceramics or slag.

[0498] The above ingot may be manufactured in the shape of, for example, a bar, a polyhedron, a cylinder, a sphere, or an irregular shape, but is not limited thereto.

[0499] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may further include the step of cutting the ingot into 4 to 30 mm.

[0500] For example, the method for manufacturing the above FeCoV alloy-based thin sheet may further include a step of cutting the ingot into 10 to 30 mm. It is desirable to further include a step of cutting the ingot within the above range so that hot rolling is smooth.

[0501] The cutting of the above ingot may be carried out by methods conventionally performed in the art, and the present invention is not limited thereto.

[0503] In another embodiment of the present invention, the method may further include the step of manufacturing an ingot by casting the molten alloy; and the step of homogenizing the ingot thereafter.

[0504] In another embodiment of the present invention, the homogenization heat treatment may be performed at 1200 to 1300°C for 1 to 12 hours.

[0505] Preferably, the homogenization heat treatment may be performed for 2 to 6 hours, more preferably for 2 to 4 hours, but is not limited thereto.

[0506] It is desirable to further include the above homogenization heat treatment step so that stress generated during casting can be relieved.

[0508] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of hot rolling the ingot to obtain a sheet material.

[0509] It is desirable to obtain a plate in which the γ-austenite phase formed by slow cooling accounts for the majority, or in which the α-ferrite phase and the γ-austenite phase are mixed by hot rolling the above ingot.

[0511] The above hot rolling can be performed, for example, using a steel rolling mill.

[0512] The above rolling start temperature, rolling speed, rolling end temperature, etc., are not specifically limited in the present invention and can be appropriately performed under ordinary conditions practiced in the industry.

[0513] For example, the starting temperature for the above rolling may be 900°C or higher and may not exceed 1300°C. When the starting temperature for the above rolling satisfies the above range, it is desirable as there is an advantage of excellent strength and formability of the sheet material being manufactured.

[0514] The above rolling end temperature may be 1150℃ or higher. When the above rolling end temperature is 1150℃ or higher, it is desirable because it can suppress the phenomenon of strain on the equipment due to high deformation resistance and facilitate shape control.

[0516] The total reduction rate by the above hot rolling may be 70 to 90%, preferably 75 to 90%, and more preferably 75 to 85%. When the total reduction rate satisfies the above range, it is desirable to suppress the increase of crystal grains caused by high energy and to reduce the deviation thereof.

[0518] The above rolling may be performed in one to several passes, but is not limited thereto.

[0519] In another embodiment of the present invention, the rolling may be performed in two or more rolling passes. Specifically, the rolling may be performed in five or more rolling passes, but is not limited thereto.

[0521] If the temperature decreases as the above hot rolling is repeated, it is desirable to raise the temperature by reheating and then perform hot rolling. It is desirable to control the lower limit of the temperature during the rolling process to 900°C or higher, preferably 900 to 1000°C.

[0522] When the lower limit of the temperature during the above rolling process satisfies the above range, it is desirable because it exists mostly in the γ-austenite phase, so cracks and bursting hardly occur during hot rolling and it becomes smooth.

[0524] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of heat-treating the sheet material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase.

[0525] Although I do not wish to be limited by theory, generally, FeCoV-based alloys undergo phase changes as they go through casting, hot rolling, heat treatment, and cold rolling processes, and even within the same phase, they change into regular and irregular lattices.

[0526] For example, when a FeCoV-based alloy is melted in a vacuum and cast into an ingot, an α-ferrite phase is formed.

[0527] In the case of α-ferrite, which is a microstructure at room temperature, it has a body-centered cubic (BCC) structure and relatively few slip planes, so there is a high possibility that cold rolling will not be performed smoothly when using FeCoV alloy-based sheet materials to make thin sheets.

[0528] In particular, due to residual stress present within the sheet metal after cold rolling, forming becomes difficult and soft magnetic properties may not be properly realized.

[0529] On the other hand, the γ-austenite structure, which is a high-temperature structure, has an irregular face-centered cubic (FCC) structure and has many slip planes, making it easy to roll, and thus its plastic workability is much better than that of α-ferrite.

[0530] Accordingly, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention involves heat-treating the sheet material at a temperature of 600 to 1200°C, which is a high-temperature stable phase region, so that it has a γ-austenite structure, which is a high-temperature stable phase, in other words, an FCC structure, and then rapidly cooling it, thereby changing the α-ferrite phase generated through the casting process and hot rolling process into a γ-austenite phase, so that it has a γ-austenite phase or a structure having a composite structure of an α-ferrite phase and a γ-austenite phase.

[0531] In another embodiment of the present invention, the heat treatment may be performed at a temperature of 730 to 1200°C. Specifically, the heat treatment may be performed at a temperature of 730°C or higher, which is the temperature at which ordering of irregular / ordered lattice structures begins, and at a temperature of 1200°C or lower, which is the temperature at which atomic structure changes are expected to be most active without the formation of a liquid phase. Specifically, it is preferable that the heat treatment be performed within the above range, which is the temperature region where irregular / ordered structural changes occur.

[0533] In another embodiment of the present invention, the heat treatment may be performed at 840 to 1200°C.

[0534] Specifically, the above heat treatment can be performed at a temperature of 840°C or higher, which is the temperature at which phase transformation occurs, and at a temperature of 1200°C or lower, which is the temperature at which solid phase control is possible without the presence of a liquid phase.

[0535] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be heat treatment at 850 to 950°C.

[0536] Since FeCoV alloy-based sheet materials can vary significantly in mechanical and / or magnetic properties depending on the heat treatment temperature even with the same composition, the present invention allows for obtaining a FeCoV alloy-based thin sheet with excellent mechanical properties and superior magnetic properties—that is, having high saturation magnetic flux density and low iron loss values ​​simultaneously—by heat treating at a temperature within the above range.

[0538] In another embodiment of the present invention, the heat treatment may be performed for 30 to 240 minutes.

[0539] Preferably, the heat treatment can be performed for 60 to 120 minutes.

[0540] When the above heat treatment time satisfies the above range, it is desirable because the phase transformation time to the γ-austenite phase is sufficient while shortening the heat treatment time.

[0541] In short, the step of changing to the γ-austenite phase may be heat treatment at a temperature of 850 to 950°C for 60 to 120 minutes.

[0543] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be performed under a vacuum or an inert gas atmosphere. Since the FeCoV-based alloy is somewhat prone to oxidation, it is preferable to perform the step of changing to the γ-austenite phase under a vacuum or an inert gas atmosphere.

[0544] The above inert gas may be, for example, high-purity argon (Ar) gas, but is not limited thereto.

[0546] In another embodiment of the present invention, a step of removing surface scale from the plate material may be further included prior to the step of heat-treating the plate material.

[0547] An oxide scale may form on the surface of the hot-rolled sheet metal. Since the oxide scale can affect the quality of the sheet metal, it is desirable to further include a step of removing the surface scale from the sheet metal.

[0548] The method for removing surface scale from the above-mentioned plate can be performed using conventional methods practiced in the industry.

[0549] For example, the above-mentioned plate may be immersed in a hydrochloric acid bath to perform pickling treatment, or a slurry mixed with high-pressure water and abrasive may be sprayed at high pressure onto the above-mentioned plate to remove the surface scale, but is not limited thereto.

[0551] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of quenching the heat-treated FeCoV alloy-based sheet material.

[0552] In the cold rolling process described later, if the microstructure of the above FeCoV alloy-based sheet material forms an regular structure, it has high strength and low elongation, which causes cracking or splitting to occur during the cold rolling process, making it difficult to roll to the target thickness.

[0553] Accordingly, in the present invention, the FeCoV alloy-based plate is heat-treated at 600 to 1200°C for 10 to 240 minutes to change the α-ferrite phase into a γ-austenite phase, thereby changing the FeCoV alloy-based plate to form a disordered structure.

[0554] After that, by including a step of rapidly cooling the above FeCoV alloy-based sheet so that it can maintain the structure of the γ-austenite phase, the elongation is improved and the problem occurring during the cold rolling process is solved.

[0555] In another embodiment of the present invention, the rapid cooling step may be rapid cooling at a rate of 10 to 300°C / sec. Preferably, the rapid cooling may be performed at a rate of 30 to 150°C / sec, more preferably at a rate of 50 to 100°C / sec.

[0556] It is desirable that when the rate of rapid cooling satisfies the above range, the γ-austenite phase is stably maintained, allowing for the production of a FeCoV alloy-based thin sheet having a high saturation magnetic flux density.

[0557] The above rapid cooling step may involve performing water cooling or oil cooling.

[0558] The above water cooling or oil cooling method is not specifically limited in the present invention, and general methods practiced in the art may be applied. For example, it may be performed using a water or oil cooling guide and a conveyor roll, but is not limited thereto.

[0559] By performing the above water cooling or oil cooling, the γ-austenite phase structure, which is a high-temperature stable phase, can be stably maintained.

[0560] The above rapid cooling step may be performed by immersing the FeCoV-based alloy plate in cooling water.

[0562] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of cold-rolling the rapidly cooled FeCoV alloy-based sheet material to obtain a FeCoV alloy-based thin sheet.

[0563] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention allows for smooth cold rolling by heat-treating an α-ferrite phase with a regular structure according to a specific temperature range and time, and then rapidly cooling it to change it into a γ-austenite phase with an irregular structure.

[0564] The above cold rolling may be performed repeatedly while varying the reduction ratio, but is not limited thereto.

[0565] The cumulative reduction rate may be 85% or more, specifically 90% or more, and more specifically 95% or more, but is not limited to this.

[0567] In another embodiment of the present invention, the method may further include the step of obtaining the FeCoV alloy-based thin sheet; and subsequently the step of performing stress relief heat treatment on the FeCoV alloy-based thin sheet.

[0568] By including a step of stress relief heat treatment of the above FeCoV alloy-based thin sheet, residual stress present inside the FeCoV alloy-based thin sheet after cold rolling can be removed, and regularity is ensured as the irregular γ-austenite phase changes into a stable phase, thereby making it desirable to obtain a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value, a low iron loss value, and appropriate tensile strength and elongation.

[0570] Soft magnetic FeCoV alloys undergo a process in which the phase of the microstructure changes during the manufacturing process of thin sheets, and in this process, the specific method of heat treatment, such as the heat treatment atmosphere, temperature, and time, affects the values ​​of magnetic properties, such as saturation magnetic flux density, residual magnetic flux density, coercivity, and core loss.

[0571] Here, when soft magnetic materials are used as materials for drive motor components, they exhibit characteristics where higher saturation magnetic flux density or magnetic flux density values ​​in a specific frequency range are advantageous, and lower loss values ​​such as iron loss are advantageous. Consequently, alloy design, processing, and heat treatment are carried out to achieve high magnetic flux density and low iron loss values. As a result, when the value obtained by dividing magnetic flux density by iron loss is defined as the high-efficiency value, the higher this value, the better the material is for motors.

[0572] In the present invention, heat treatment for microstructure control is performed between hot rolling and cold rolling to facilitate cold rolling, and additional stress relief heat treatment is performed after cold rolling to improve mechanical properties, particularly elongation and magnetic properties, thereby providing the advantage of being able to manufacture FeCoV alloy-based thin sheets with excellent mechanical and magnetic properties.

[0573] In another embodiment of the present invention, the stress relief heat treatment may be performed at 650 to 950°C for 10 to 120 minutes.

[0574] Preferably, the stress relief heat treatment may be performed at a temperature of 700 to 950°C, more preferably 850 to 950°C, but is not limited thereto.

[0576] Another aspect of the present invention relates to a FeCoV alloy-based thin sheet containing 49 to 66 at% (atomic percent) of iron, 20 to 49 at% of cobalt, more than 0 and less than or equal to 2 at% of vanadium, 0 to 15 at% of nickel, 0 to 3 at% of chromium, and 0 to 1 at% of niobium.

[0577] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a saturation magnetic flux density of 2.13 to 2.38 T.

[0578] Specifically, the above FeCoV alloy-based thin sheet may have a saturation magnetic flux density of 2.26 to 2.38 T.

[0579] The above saturation magnetic flux density and the magnetic flux density in a specific section to be described later are factors related to output. Specifically, in cases requiring high instantaneous output, such as electric vehicle motors, a high saturation magnetic flux density of 2T or more is required.

[0580] The FecoV alloy-based thin sheet according to the present invention has a high saturation magnetic flux density, so it can be usefully applied in various fields, and in particular, it can have a saturation magnetic flux density of 2T or more, so it can be usefully applied in electric vehicles.

[0581] In the present invention, the “saturation magnetic flux density” is 1.2 × 10⁻⁶ of an applied magnetic field using a vibrating sample type magnetometer (VSM). 3 It refers to what is measured in kA / m.

[0582] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 43 Oe or less.

[0583] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 25 Oe or less.

[0584] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 10 Oe or less.

[0585] Specifically, the above FeCoV alloy-based thin sheet may have a coercivity of 1 Oe or less, more specifically 0.5 Oe or less, and most specifically 0.18 to 0.5 Oe.

[0586] If the coercivity of the above FeCoV alloy-based thin sheet satisfies the above range, it is desirable as it has the advantage of excellent processability.

[0589] Another aspect of the present invention relates to a method for manufacturing a FeCoV alloy-based thin sheet, comprising the steps of: preparing a FeCoV alloy-based casting; heat-treating the casting at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated casting; and cold-rolling the rapidly cooled casting.

[0590] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of being able to manufacture a FeCoV alloy-based thin sheet with excellent magnetic properties while omitting conventional processes such as forging and hot rolling.

[0591] A method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of preparing a FeCoV alloy-based casting material.

[0592] In another embodiment of the present invention, the step of preparing the FeCoV alloy-based casting material may include: the step of preparing a FeCoV alloy molten metal; the step of manufacturing an ingot by casting the alloy molten metal; and the step of obtaining a casting material by cutting the ingot to a thickness of 4 to 10 mm.

[0593] In another embodiment of the present invention, the step of preparing the FeCoV alloy-based casting material may be the step of forming the FeCoV alloy-based casting material by a strip casting process.

[0594] In short, the above FeCoV alloy-based casting material may be obtained by cutting the above ingot, or it may be directly manufactured from the molten alloy in the form of a plate having a thickness of 4 to 10 mm.

[0596] The step of preparing the above FeCoV alloy molten metal may involve vacuum melting the alloy components composed of 20 to 49 at% cobalt, 2 to 5 at% vanadium, and the remainder being iron and other impurities.

[0597] The above other impurities may be one or more selected from the group consisting of carbon, oxygen, silicon, and manganese.

[0598] Specifically, the above-mentioned FeCoV alloy molten metal may contain alloy components composed of 30 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0599] More specifically, the above-mentioned FeCoV alloy molten metal may contain alloy components composed of 40 to 49 at% cobalt, 2 to 3 at% vanadium, and the remainder being iron and other impurities.

[0600] FeCoV-based alloys are alloy compositions with soft magnetic properties. Manufactured into thin sheets, they are primarily used in motor cores for electronic products, and recently, their application as drive motors for electric vehicles is being considered.

[0601] To increase the output of electric vehicles, the magnetic flux density of the motor core material must be high. Most recent electric vehicles have values ​​exceeding 2 Tesla, and since FeCoV alloys can reach up to 2.4 Tesla, they can be highly beneficial for improving motor core output. Furthermore, they possess significantly lower iron loss values ​​compared to other soft magnetic materials, which not only improves efficiency but also enables longer driving distances due to lower losses relative to batteries of the same capacity. For the same reasons, it is possible to miniaturize and lighten motors that exhibit the same performance.

[0602] For such FeCoV alloys, the rolling process defect rate can vary depending on the manufacturing process, even if the alloy composition is the same, and the mechanical and magnetic properties of the manufactured sheet can be significantly affected.

[0603] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of easily manufacturing a thin sheet having high mechanical and magnetic properties without including conventional complex slag removal processes, forging processes, and slab shape forming processes.

[0604] Meanwhile, the saturation magnetic flux density and coercivity values ​​of the FeCoV alloy-based thin sheet manufactured according to the composition of the above FeCoV alloy components may vary slightly.

[0605] In the present invention, by using an FeCoV alloy component having the composition described above, there is an advantage in obtaining a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value and low coercivity.

[0606] The above FeCoV alloy molten metal is Fe 49 Co 49 It can have V2 composition.

[0607] By vacuum melting the above alloy components, a gray ingot with low contamination can be obtained, and when solidified into an ingot shape through the casting step described later, it is desirable to suppress the phenomenon in which an ingot with an uneven composition is obtained due to compositional inconsistency, such as when the composition of the upper and middle parts or the middle and lower parts of the ingot differs, or when segregation exists in the same part. In addition, it is desirable to suppress the phenomenon in which cracks are induced during the cold rolling process, etc., due to the oxide layer being too thick.

[0609] The step of preparing the molten alloy may be performed under an argon, nitrogen, or carbon dioxide atmosphere. It is preferable that the step of preparing the molten alloy be performed under an argon, nitrogen, or carbon dioxide atmosphere, as this can suppress the oxidation or carbonization of the alloy components.

[0611] In the step of preparing a molten FeCoV alloy by vacuum melting the above alloy components, the vacuum level is 1×10 -2 Up to 1×10 -4 torr, preferably 1×10 -2 Up to 1×10 -3 It could be torr.

[0612] If the above vacuum level satisfies the above range, it is desirable to be able to suppress oxidation or carbonization.

[0614] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of manufacturing an ingot by casting the molten alloy.

[0615] The method may further include, but is not limited to, a step of removing slag from the molten alloy liquid prior to casting the molten alloy.

[0616] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may not include a step of removing slag from the molten alloy. Specifically, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention has the advantage of being able to manufacture a FeCoV alloy-based thin sheet exhibiting excellent performance without including a slag removal process, a forging process, or a shape-controlled sraving process.

[0617] The method of manufacturing an ingot by casting the above-mentioned molten alloy is not specifically limited in the present invention.

[0618] For example, the molten alloy can be poured into a mold and cooled and crystallized to produce an ingot.

[0619] It is preferable that the injection temperature be 100 to 2000°C, preferably 100 to 1000°C, and more preferably 200 to 500°C higher than the liquid phase temperature of the molten metal. The liquid phase temperature of the molten metal can be measured using a direct temperature measurement method with a built-in thermocouple or by using a non-contact laser thermometer on the surface of the molten metal.

[0620] In addition, the cooling temperature and speed can be controlled to ensure uniformity of composition and prevent segregation. Since the upper part of the ingot cools relatively quickly while the lower part or interior cools slowly, the parts that cool quickly can be heated, or they can be insulated with non-metallic ceramics or slag.

[0622] The above ingot may be manufactured in the shape of, for example, a bar, a polyhedron, a cylinder, a sphere, or an irregular shape, but is not limited thereto.

[0623] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may further include the step of cutting the ingot into 4 to 10 mm. Specifically, when cold rolling is performed without undergoing the step of hot rolling the ingot, the method may further include the step of cutting the ingot into 4 to 10 mm.

[0624] The cutting of the above ingot may be carried out by methods conventionally performed in the art, and the present invention is not limited thereto.

[0626] In another embodiment of the present invention, the method may further include the step of manufacturing an ingot by casting the molten alloy; and the step of homogenizing the ingot thereafter.

[0627] In another embodiment of the present invention, the homogenization heat treatment may be performed at 1200 to 1300°C for 1 to 12 hours.

[0628] Preferably, the homogenization heat treatment may be performed for 2 to 6 hours, more preferably for 2 to 4 hours, but is not limited thereto.

[0629] It is desirable to further include the above homogenization heat treatment step so that stress generated during casting can be relieved.

[0631] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention may include the step of cutting the ingot to a thickness of 4 to 10 mm to obtain a casting material.

[0632] In another embodiment of the present invention, the step of obtaining the casting material may be to cut the ingot to a thickness of 4 to 8 mm.

[0633] In another embodiment of the present invention, the step of obtaining the casting material may be to cut the ingot to a thickness of 4 to 6 mm.

[0634] In short, the above-mentioned casting material may have a thickness of 4 to 10 mm, preferably 4 to 8 mm, and more preferably 4 to 6 mm.

[0635] If the thickness of the above-mentioned casting satisfies the above range, the cold rolling process described later is easy and therefore desirable.

[0637] The above casting material may be formed by a strip casting process.

[0638] The above strip casting process is a process technology that manufactures solid thin sheets directly from a liquid molten metal. It is a technology that manufactures thin sheets with a thickness of 4 to 10 mm, and it is a process that can improve productivity by eliminating continuous casting, reheating, and hot rolling processes.

[0639] The present invention does not specifically limit the strip casting process method.

[0640] For example, the above strip casting process may be performed by controlling the cooling of the FeCoV alloy molten at a temperature of 1700°C or higher to 300°C at a cooling rate of 100 to 150°C / s, but is not limited thereto.

[0642] In another embodiment of the present invention, the step of obtaining the casting material may be performed under an argon, nitrogen, or carbon dioxide atmosphere.

[0643] It is preferable that the step of obtaining the above-mentioned casting material be performed in an inert atmosphere such as argon or nitrogen, or under a carbon dioxide atmosphere, so that the oxidation or carbonization of the casting material can be suppressed.

[0645] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of heat-treating the casting material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase.

[0646] Although I do not wish to be limited by theory, generally, FeCoV-based alloys undergo phase changes as they go through casting, heat treatment, and cold rolling processes, and even within the same phase, they change into regular and irregular lattices.

[0647] For example, a casting obtained by melting a FeCoV-based alloy in a vacuum forms an α-ferrite phase.

[0648] In the case of α-ferrite, which is a microstructure at room temperature, it has a body-centered cubic (BCC) structure and has relatively few slip planes, so there is a high possibility that cold rolling will not be performed smoothly when using the above-mentioned casting material to make a thin sheet.

[0649] In particular, due to residual stress present inside the casting material after cold rolling, forming may be difficult and soft magnetic properties may not be properly realized.

[0650] On the other hand, the γ-austenite structure, which is a high-temperature structure, has an irregular face-centered cubic (FCC) structure and has many slip planes, making it easy to roll, and thus its plastic workability is much better than that of α-ferrite.

[0651] Accordingly, the method for manufacturing a FeCoV alloy-based thin sheet according to the present invention involves heat-treating the casting material at a temperature of 600 to 1200°C, which is a high-temperature stable phase region, so that it has a γ-austenite structure, which is a high-temperature stable phase, in other words, an FCC microstructure, and then rapidly cooling it, thereby changing the α-ferrite phase generated through the casting process and hot rolling process into a γ-austenite phase, so that it has a γ-austenite phase or a structure having a composite microstructure of an α-ferrite phase and a γ-austenite phase.

[0652] In another embodiment of the present invention, the heat treatment may be performed at a temperature of 730 to 1200°C. Specifically, the heat treatment may be performed at a temperature of 730°C or higher, which is the temperature at which ordering of irregular / ordered lattice structures begins, and at a temperature of 1200°C or lower, which is the temperature at which atomic structure changes are expected to be most active without the formation of a liquid phase. Specifically, it is preferable that the heat treatment be performed within the above range, which is the temperature region where irregular / ordered structural changes occur.

[0654] In another embodiment of the present invention, the heat treatment may be performed at 840 to 1200°C.

[0655] Specifically, the above heat treatment can be performed at a temperature of 840°C or higher, which is the temperature at which phase transformation occurs, and at a temperature of 1200°C or lower, which is the temperature at which solid phase control is possible without the presence of a liquid phase.

[0656] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be heat treatment at 850 to 950°C.

[0657] Since the mechanical and / or magnetic properties of FeCoV alloy-based thin sheets can vary significantly depending on the heat treatment temperature even with the same composition, the present invention allows for obtaining a FeCoV alloy-based thin sheet with excellent mechanical properties and superior magnetic properties—that is, having high saturation magnetic flux density and low iron loss values ​​simultaneously—by heat treating at a temperature within the above range.

[0658] When the heat treatment temperature satisfies the above range, the phase change in which the α-ferrite phase changes into the γ-austenite phase is facilitated, and the formation of coarse grain boundaries of 100 to 500 μm is suppressed, thereby having the advantage of obtaining a cast material with high machinability.

[0659] In addition, there is an advantage in that the phenomenon of the composition ratio between the surface and interior of the above-mentioned casting material—specifically the composition ratio of Fe and Co—changing can be suppressed, thereby obtaining a casting material with overall uniform quality.

[0661] In another embodiment of the present invention, the heat treatment may be performed for 30 to 240 minutes.

[0662] Preferably, the heat treatment can be performed for 60 to 120 minutes.

[0663] When the above heat treatment time satisfies the above range, it is desirable because the phase transformation time to the γ-austenite phase is sufficient while shortening the heat treatment time.

[0664] In short, the step of changing to the γ-austenite phase may be heat treatment at a temperature of 850 to 950°C for 60 to 120 minutes.

[0666] In another embodiment of the present invention, the step of changing to the γ-austenite phase may be performed under a vacuum or an inert gas atmosphere. Since the FeCoV-based alloy is somewhat prone to oxidation, it is preferable to perform the step of changing to the γ-austenite phase under a vacuum or an inert gas atmosphere.

[0667] The above inert gas may be, for example, high-purity argon (Ar) gas, but is not limited thereto.

[0669] In another embodiment of the present invention, the step of chemically grinding the casting material before heat treating the casting material may be further included.

[0670] Due to the process characteristics, the above casting material is produced by directly rolling and rapidly cooling the molten metal, which may result in surface casting defects such as solidification patterns or inverse segregation.

[0671] In addition, since the thickness is somewhat thin at 4 to 10 mm, it is not easy to apply conventional physical surface grinding processes for removing surface defects, such as band saw type processes or grinder type processes.

[0672] Therefore, surface casting defects can be removed by chemically grinding the casting material before heat treating the casting material.

[0673] The above chemical grinding step can be performed by conventional methods practiced in the art and is not specifically limited in the present invention.

[0674] For example, the above chemical abrasion can be performed using a composition comprising hydrochloric acid, nitric acid, hydrofluoric acid, and distilled water.

[0676] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of quenching the heat-treated casting material.

[0677] In the cold rolling process described later, if the microstructure of the cast material has a regular structure, it has high strength and low elongation, which causes cracking or splitting to occur during the cold rolling process, making it difficult to roll to the target thickness.

[0678] Specifically, the heat-treated casting is composed of an α phase, and the α phase has a BCC structure with few slip planes, so it is not suitable for shape deformation processes such as cold rolling.

[0679] Accordingly, in the present invention, the casting material is heat-treated at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into the γ-austenite phase, thereby changing the casting material to form a disordered structure.

[0680] After that, by including a step of rapidly cooling the above-mentioned casting material so that it can maintain the structure of the γ-austenite phase, the elongation is improved and the problem occurring during the cold rolling process is solved.

[0681] In another embodiment of the present invention, the rapid cooling step may be rapid cooling at a rate of 10 to 300°C / sec. Preferably, the rapid cooling may be performed at a rate of 30 to 150°C / sec, more preferably at a rate of 50 to 100°C / sec.

[0682] It is desirable that when the rate of rapid cooling satisfies the above range, the γ-austenite phase is stably maintained, allowing for the production of a FeCoV alloy-based thin sheet having a high saturation magnetic flux density.

[0683] The above rapid cooling step may involve performing water cooling or oil cooling.

[0684] The above water cooling or oil cooling method is not specifically limited in the present invention, and general methods practiced in the art may be applied. For example, it may be performed using a water or oil cooling guide and a conveyor roll, but is not limited thereto.

[0685] By performing the above water cooling or oil cooling, the γ-austenite phase structure, which is a high-temperature stable phase, can be stably maintained.

[0686] The above rapid cooling step may be performed by immersing the casting material in cooling water.

[0688] A method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the step of cold-rolling the rapidly cooled casting material to obtain a FeCoV alloy-based thin sheet.

[0689] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention allows for smooth cold rolling by heat-treating an α-ferrite phase with a regular structure according to a specific temperature range and time, and then rapidly cooling it to change it into a γ-austenite phase with an irregular structure.

[0690] The above cold rolling may be performed repeatedly while varying the reduction ratio, but is not limited thereto.

[0691] The cumulative reduction rate may be 85% or more, specifically 90% or more, and more specifically 95% or more, but is not limited to this.

[0693] In another embodiment of the present invention, the method may further include the step of obtaining the FeCoV alloy-based thin sheet; and subsequently the step of performing stress relief heat treatment on the FeCoV alloy-based thin sheet.

[0694] By including a step of stress relief heat treatment of the above FeCoV alloy-based thin sheet, residual stress present inside the FeCoV alloy-based thin sheet after cold rolling can be removed, and regularity is ensured as the irregular γ-austenite phase changes into a stable phase, thereby making it desirable to obtain a FeCoV alloy-based thin sheet having a high saturation magnetic flux density value, a low iron loss value, and appropriate tensile strength and elongation.

[0696] Soft magnetic FeCoV alloys undergo a process in which the phase of the microstructure changes during the manufacturing process of thin sheets, and in this process, the specific method of heat treatment, such as the heat treatment atmosphere, temperature, and time, affects the values ​​of magnetic properties, such as saturation magnetic flux density, residual magnetic flux density, coercivity, and core loss.

[0697] Here, when soft magnetic materials are used as materials for drive motor components, they exhibit characteristics where higher saturation magnetic flux density or magnetic flux density values ​​in a specific frequency range are advantageous, and lower loss values ​​such as iron loss are advantageous. Consequently, alloy design, processing, and heat treatment are carried out to achieve high magnetic flux density and low iron loss values. As a result, when the value obtained by dividing magnetic flux density by iron loss is defined as the high-efficiency value, the higher this value, the better the material is for motors.

[0698] In the present invention, heat treatment for microstructure control is performed between hot rolling and cold rolling to facilitate cold rolling, and additional stress relief heat treatment is performed after cold rolling to improve mechanical properties, particularly elongation and magnetic properties, thereby providing the advantage of being able to manufacture FeCoV alloy-based thin sheets with excellent mechanical and magnetic properties.

[0699] In another embodiment of the present invention, the stress relief heat treatment may be performed at 650 to 950°C for 10 to 120 minutes.

[0700] Preferably, the stress relief heat treatment may be performed at a temperature of 700 to 950°C, more preferably 850 to 950°C, but is not limited thereto.

[0702] The method for manufacturing a FeCoV alloy-based thin sheet according to the present invention includes the steps of heat treatment and rapid cooling, thereby having the advantage of being able to manufacture a FeCoV alloy-based thin sheet having the same level of soft magnetic performance as the conventional process involving forging, hot rolling, and cold rolling, by cold rolling alone without undergoing the conventional forging and hot rolling processes.

[0704] Another aspect of the present invention relates to a FeCoV alloy-based thin sheet, wherein 2θ in an X-ray diffraction chart obtained by XRD analysis has a first peak in the range of 42 to 47°, a second peak in the range of 62 to 67°, and a third peak in the range of 80 to 85°.

[0705] In another embodiment of the present invention, the second peak may be the maximum peak intensity.

[0706] In another embodiment of the present invention, the third peak may be the maximum peak intensity.

[0707] Specifically, in the FeCoV alloy-based thin sheet according to the present invention, the second peak or the third peak may exhibit maximum peak intensity depending on the stress relief heat treatment among the manufacturing methods of the FeCoV alloy-based thin sheet.

[0708] More specifically, if stress relief heat treatment is not performed during the process of manufacturing the above FeCoV alloy-based thin sheet, the above second peak may exhibit maximum peak intensity, and if stress relief heat treatment is performed, the above third peak may exhibit maximum peak intensity.

[0709] In another embodiment of the present invention, the full width at half maximum of the second peak may be in the range of 4.5 to 4.6°. Specifically, when stress relief heat treatment is not performed during the process of manufacturing the FeCoV alloy-based thin sheet, the full width at half maximum of the second peak may be in the above range.

[0710] In another embodiment of the present invention, the full width at half maximum of the second peak may be in the range of 0.35 to 0.36°. Specifically, when stress relief heat treatment is performed during the process of manufacturing the FeCoV alloy-based thin sheet, the full width at half maximum of the second peak may be in the above range.

[0711] In another embodiment of the present invention, the permeability may be 10,000 or less. Specifically, if stress relief heat treatment is not performed during the process of manufacturing the FeCoV alloy-based thin sheet, the permeability of the FeCoV alloy-based thin sheet may be 7,000 or less.

[0712] In another embodiment of the present invention, the permeability may be 80,000 or higher. Specifically, when stress relief heat treatment is performed during the process of manufacturing a FeCoV alloy-based thin sheet, the FeCoV alloy-based thin sheet may have a permeability of 80,000 or higher. Specifically, the permeability may be 80,000 to 100,000.

[0714] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a saturation magnetic flux density of 2.13 to 2.38 T.

[0715] Specifically, the above FeCoV alloy-based thin sheet may have a saturation magnetic flux density of 2.26 to 2.38 T.

[0716] The above saturation magnetic flux density and the magnetic flux density in a specific section to be described later are factors related to output. Specifically, in cases requiring high instantaneous output, such as electric vehicle motors, a high saturation magnetic flux density of 2T or more is required.

[0717] The FecoV alloy-based thin sheet according to the present invention has a high saturation magnetic flux density, so it can be usefully applied in various fields, and in particular, it can have a saturation magnetic flux density of 2T or more, so it can be usefully applied in electric vehicles.

[0718] In the present invention, the “saturation magnetic flux density” is 1.2 × 10⁻⁶ of an applied magnetic field using a vibrating sample type magnetometer (VSM). 3 It refers to what is measured in kA / m.

[0720] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a magnetic flux density of 1.5T or more when a magnetic field of 5000 A / m is applied.

[0721] Specifically, the magnetic flux density may be 1.87 to 2.2207 T.

[0723] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 43 Oe or less.

[0724] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 25 Oe or less.

[0725] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 10 Oe or less.

[0726] Specifically, the above FeCoV alloy-based thin sheet may have a coercivity of 1 Oe or less, more specifically 0.5 Oe or less, and most specifically 0.18 to 0.5 Oe.

[0727] If the coercivity of the above FeCoV alloy-based thin sheet satisfies the above range, it is desirable as it has the advantage of excellent processability.

[0729] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have an iron loss of 15 or less.

[0730] In the present invention, “iron loss” may be measured under conditions where the magnitude of the applied magnetic field is 1T and the frequency is 400Hz.

[0731] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may contain a γ-austenite phase.

[0732] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may further contain an α-ferrite phase.

[0733] In short, the above FeCoV alloy thin sheet may contain a γ-austenite phase, or it may be in the form of a composite phase containing a γ-austenite phase and an α-ferrite phase.

[0735] The FeCoV alloy-based thin sheet according to the present invention contains a γ-austenite phase or contains both a γ-austenite phase and an α-ferrite phase, so it exhibits excellent magnetic properties and excellent mechanical properties, and in particular, is easy to post-process, making it useful for application in various fields.

[0737] In another embodiment of the present invention, the average band thickness of the elongated layered structure of the γ-austenite phase in the L cross-section, which is a cross-section parallel to the rolling direction, may be 1 to 10 μm.

[0738] In another embodiment of the present invention, the average band thickness of the elongated layered structure of the γ-austenite phase in the L cross-section, which is a cross-section parallel to the rolling direction, may be 1 to 5 μm.

[0739] Specifically, in the L cross-section which is a cross-section parallel to the rolling direction, the average band thickness of the γ-austenite phase in the elongated layered structure may be 2 to 4 μm.

[0740] If the above average band thickness satisfies the above range, it means that the cold rolling of the FeCoV alloy-based thin sheet was smooth, and accordingly, there is an advantage of exhibiting excellent mechanical properties as well as magnetic properties.

[0741] The above FeCoV alloy-based thin sheet can be manufactured by a method for manufacturing a FeCoV alloy-based thin sheet comprising: a step of preparing a FeCoV alloy-based sheet material; a step of heat-treating the FeCoV alloy-based sheet material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; a step of rapidly cooling the heat-treated FeCoV alloy-based sheet material; a step of cold-rolling the rapidly cooled FeCoV alloy-based sheet material to obtain a FeCoV alloy-based thin sheet; and a step of stress-relieving heat treatment of the FeCoV alloy-based thin sheet material; wherein the half-width of the maximum peak in the range of 2θ to 42 to 47° in the X-ray diffraction chart obtained by XRD analysis before and after heat-treating the FeCoV alloy-based sheet material is different.

[0742] In another embodiment of the present invention, the full width at half maximum of the peak in the range of 2θ to 42 to 47° in the X-ray diffraction chart obtained by XRD analysis before and after the stress relief heat treatment of the FeCoV alloy-based thin plate may be different.

[0743] The specific manufacturing steps of the above method for manufacturing the FeCoV alloy-based thin sheet can be applied as described above.

[0745] Another aspect of the present invention relates to a FeCoV alloy-based thin sheet comprising γ-austenite and residual α-ferrite, with an average grain size of 50 to 100 μm.

[0746] The FeCoV alloy-based thin sheet according to the present invention contains γ-austenite and residual α-ferrite, and thus has excellent magnetic properties and is easy to process afterward, so it has the advantage of being usefully applicable in various fields, especially as a material for electric vehicles.

[0748] In another embodiment of the present invention, the average size of the crystal grains may be 50 to 80 μm.

[0749] In another embodiment of the present invention, the average size of the crystal grains may be 50 to 60 μm.

[0750] If the average size of the crystal grains satisfies the above range, it is desirable as it has the advantage of excellent magnetic properties.

[0752] In the present invention, the “average size of the grains” may be based on the ASTM E112 standard.

[0753] The average size of the above “grains” may refer to the overall average size of the above γ-austenite grains and the above α-ferrite grains.

[0754] The average size of the γ-austenite grains may be 50 to 100 μm, preferably 50 to 80 μm, and more preferably 50 to 60 μm.

[0756] In another embodiment of the present invention, the area fraction of the γ-austenite may be larger than the area fraction of the α-ferrite.

[0757] When the area fraction of the γ-austenite is greater than the area fraction of the α-ferrite, it means that cold rolling has been performed smoothly, and as a result, the FeCoV alloy-based thin sheet has the advantage of having a high saturation magnetic flux density, low coercivity, and low iron loss value, which is desirable.

[0759] In another embodiment of the present invention, the area fraction of the γ-austenite may be 60 to 95%.

[0760] In another embodiment of the present invention, the area fraction of the α-ferrite may be 5 to 50%.

[0761] When the area fraction of the γ-austenite and the area fraction of the α-ferrite satisfy the above range, it is desirable as it has the advantage of excellent magnetic properties and easy processability.

[0763] In another embodiment of the present invention, the ratio of the number of γ-austenite and α-ferrite may be 80:20 to 60:40.

[0764] Specifically, the number of the γ-austenite and α-ferrite may be based on ASTM E112 standards.

[0765] Preferably, the ratio of the number of γ-austenite and α-ferrite may be 70:30 to 60:40.

[0766] When the ratio of the number of γ-austenite and α-ferrite satisfies the above range, it is desirable because it has excellent soft magnetic properties and excellent mechanical properties, and particularly has the advantage of excellent machinability.

[0768] In another embodiment of the present invention, the number of γ-austenite grains, each having a size of 50 to 100 μm based on ASTM E112, may be 5 to 12.

[0769] Preferably, the number of the γ-austenite grains may be 7 to 10.

[0770] When the number of the above γ-austenite grains satisfies the above range, it is desirable as it has the advantage of excellent post-processability.

[0772] In another embodiment of the present invention, the number of α-ferrite crystal grains, each having a size of 50 to 100 μm based on ASTM E112, may be 2 to 8.

[0773] Preferably, the number of the α-ferrite grains may be 2 to 6, and more preferably 4 to 6.

[0774] It is desirable when the number of the above α-ferrite grains satisfies the above range because the mechanical properties are excellent.

[0776] The FeCoV alloy-based thin sheet according to the present invention contains γ-austenite and residual α-ferrite, and since the average grain size is 50 to 100 μm, it has the advantage of excellent mechanical performance as well as magnetic properties.

[0778] The FeCoV alloy-based thin sheet according to the present invention can be manufactured by the method for manufacturing the FeCoV alloy-based thin sheet described above.

[0779] For example, the above FeCoV alloy-based thin sheet may be manufactured by a method for manufacturing a FeCoV alloy-based thin sheet comprising, but is not limited to, the step of preparing a FeCoV alloy-based sheet material; the step of heat-treating the FeCoV alloy-based sheet material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; the step of rapidly cooling the heat-treated FeCoV alloy-based sheet material; and the step of cold-rolling the rapidly cooled FeCoV alloy-based sheet material to obtain a FeCoV alloy-based thin sheet.

[0780] The specific manufacturing steps of the above-mentioned method for manufacturing the FeCoV alloy-based thin sheet can be applied to the aforementioned details.

[0781] The average grain size, area fraction of γ-austenite and α-ferrite, number, etc. of the above FeCoV alloy-based thin sheet may vary depending on the heat treatment temperature during the process of manufacturing the FeCoV alloy-based thin sheet.

[0783] Another aspect of the present invention relates to a driving motor comprising: a rotor; and a stator; wherein one or more selected from the group consisting of the rotor and the stator comprise a laminate having a stack of FeCoV alloy-based thin sheets, and wherein the FeCoV alloy-based thin sheets have a first peak in the range of 42 to 47°, a second peak in the range of 62 to 67°, and a third peak in the range of 80 to 85° in an X-ray diffraction chart obtained by XRD analysis.

[0784] In another embodiment of the present invention, the second peak may be the maximum peak intensity.

[0785] In another embodiment of the present invention, the third peak may be the maximum peak intensity.

[0786] Specifically, in the FeCoV alloy-based thin sheet according to the present invention, the second peak or the third peak may exhibit maximum peak intensity depending on the stress relief heat treatment among the manufacturing methods of the FeCoV alloy-based thin sheet.

[0787] More specifically, if stress relief heat treatment is not performed during the process of manufacturing the above FeCoV alloy-based thin sheet, the above second peak may exhibit maximum peak intensity, and if stress relief heat treatment is performed, the above third peak may exhibit maximum peak intensity.

[0788] In another embodiment of the present invention, the full width at half maximum of the second peak may be in the range of 4.5 to 4.6°. Specifically, when stress relief heat treatment is not performed during the process of manufacturing the FeCoV alloy-based thin sheet, the full width at half maximum of the second peak may be in the above range.

[0789] In another embodiment of the present invention, the full width at half maximum of the second peak may be in the range of 0.35 to 0.36°. Specifically, when stress relief heat treatment is performed during the process of manufacturing the FeCoV alloy-based thin sheet, the full width at half maximum of the second peak may be in the above range.

[0790] In another embodiment of the present invention, the permeability may be 10,000 or less. Specifically, if stress relief heat treatment is not performed during the process of manufacturing the FeCoV alloy-based thin sheet, the permeability of the FeCoV alloy-based thin sheet may be 7,000 or less.

[0791] In another embodiment of the present invention, the permeability may be 80,000 or higher. Specifically, when stress relief heat treatment is performed during the process of manufacturing a FeCoV alloy-based thin sheet, the FeCoV alloy-based thin sheet may have a permeability of 80,000 or higher. Specifically, the permeability may be 80,000 to 100,000.

[0792] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a saturation magnetic flux density of 2.13 to 2.38 T.

[0793] Specifically, the above FeCoV alloy-based thin sheet may have a saturation magnetic flux density of 2.26 to 2.38 T.

[0794] The above saturation magnetic flux density and the magnetic flux density in a specific section to be described later are factors related to output. Specifically, in cases requiring high instantaneous output, such as electric vehicle motors, a high saturation magnetic flux density of 2T or more is required.

[0795] The FecoV alloy-based thin sheet according to the present invention has a high saturation magnetic flux density, so it can be usefully applied in various fields, and in particular, it can have a saturation magnetic flux density of 2T or more, so it can be usefully applied in electric vehicles.

[0796] In the present invention, the “saturation magnetic flux density” is 1.2 × 10⁻⁶ of an applied magnetic field using a vibrating sample type magnetometer (VSM). 3 It refers to what is measured in kA / m.

[0798] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a magnetic flux density of 1.5T or more when a magnetic field of 5000 A / m is applied.

[0799] Specifically, the magnetic flux density may be 1.87 to 2207 T.

[0801] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 43 Oe or less.

[0802] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 25 Oe or less.

[0803] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have a coercivity of 10 Oe or less.

[0804] Specifically, the above FeCoV alloy-based thin sheet may have a coercivity of 1 Oe or less, more specifically 0.5 Oe or less, and most specifically 0.18 to 0.5 Oe.

[0805] If the coercivity of the above FeCoV alloy-based thin sheet satisfies the above range, there is an advantage that it can be usefully applied to electric vehicles.

[0807] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may have an iron loss of 15 or less.

[0808] In the present invention, “iron loss” may be measured under conditions where the magnitude of the applied magnetic field is 1T and the frequency is 400Hz.

[0810] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may contain a γ-austenite phase.

[0811] In another embodiment of the present invention, the FeCoV alloy-based thin sheet may further contain an α-ferrite phase.

[0812] In short, the above FeCoV alloy thin sheet may contain a γ-austenite phase, or it may be in the form of a composite phase containing a γ-austenite phase and an α-ferrite phase.

[0814] The driving motor according to the present invention utilizes a FeCoV alloy-based thin sheet containing a γ-austenite phase or a γ-austenite phase and an α-ferrite phase, and thus exhibits excellent magnetic properties while also having excellent mechanical properties, making it particularly useful as a driving motor for electric vehicles.

[0816] In another embodiment of the present invention, the average band thickness of the elongated layered structure of the γ-austenite phase in the L cross-section, which is a cross-section parallel to the rolling direction, may be 1 to 10 μm.

[0817] In another embodiment of the present invention, the average band thickness of the elongated layered structure of the γ-austenite phase in the L cross-section, which is a cross-section parallel to the rolling direction, may be 1 to 5 μm.

[0818] Specifically, in the L cross-section which is a cross-section parallel to the rolling direction, the average band thickness of the γ-austenite phase in the elongated layered structure may be 2 to 4 μm.

[0819] If the above average band thickness satisfies the above range, it means that the cold rolling of the FeCoV alloy-based thin sheet was smooth, and accordingly, the driving motor including the FeCoV alloy-based thin sheet has the advantage of exhibiting excellent mechanical properties as well as magnetic properties.

[0821] In another embodiment of the present invention, the total weight may be 50 kg or less, and the efficiency may be 96% or more when the motor output is 220 kW.

[0822] The drive motor according to the present invention may be a drive motor for an electric vehicle suitable for rotating at 12,000 to 28,000 rpm.

[0824] The above rotor may include a laminate formed by laminating the aforementioned FeCoV alloy-based thin sheets.

[0825] The above stator may include a laminate formed by stacking the aforementioned FeCoV alloy-based thin plates.

[0826] The rotor and stator above may include a laminate formed by laminating the aforementioned FeCoV alloy-based thin plates.

[0828] The above-described drive motor may additionally include, but is not limited to, a battery as a main power source, an inverter that converts the DC voltage supplied from the motor and the battery, a coil wound on a rotor core, an MCU that controls the voltage supply, and a current controller that supplies power from the battery to the coil.

[0830] The above FeCoV alloy-based thin sheet may be manufactured by any one of the manufacturing methods of the above-described FeCoV alloy-based thin sheet.

[0831] For example, another aspect of the present invention relates to a method for manufacturing a drive motor component comprising the steps of: preparing an FeCoV alloy-based sheet; heat-treating the FeCoV alloy-based sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated FeCoV alloy-based sheet; cold-rolling the rapidly cooled FeCoV alloy-based sheet to obtain an FeCoV alloy-based thin sheet; processing the FeCoV alloy-based thin sheet; and laminating the FeCoV alloy-based thin sheet after processing.

[0832] The above FeCoV alloy-based thin sheet has a first peak in the range of 42 to 47° in the X-ray diffraction chart obtained by XRD analysis, a second peak in the range of 62 to 67°, and a third peak in the range of 80 to 85°.

[0833] A driving motor component according to the present invention can be manufactured by undergoing the steps of: processing the FeCoV alloy-based thin sheet in the above-described method for manufacturing the FeCoV alloy-based thin sheet; and laminating the FeCoV alloy-based thin sheet after processing.

[0834] In short, the above FeCoV alloy-based thin sheet may be manufactured using the manufacturing method of the above-described FeCoV alloy-based thin sheet.

[0835] The specific manufacturing steps of the above method for manufacturing the FeCoV alloy-based thin sheet can be applied as described above.

[0837] The above processing step may be a step of processing multiple sheets of the FeCoV alloy-based thin plate into a core shape.

[0838] The above processing process may be performed using a laser, but is not limited thereto.

[0839] For example, the above processing process can be performed by cutting with a laser at a scanning speed of 10,000 mm / min or more to obtain a drive motor component suitable for high efficiency of the motor, but is not limited thereto.

[0841] The step of laminating the above FeCoV alloy-based thin plates may be mutually fixed using adhesives or the like, but is not limited thereto.

[0842] For example, the laminated plates may be laminated through a coating process in which an adhesive is applied to both sides of the processed FeCoV alloy-based thin plate, a drying process in which the FeCoV alloy-based thin plate with the applied adhesive is dried to first cure the applied adhesive, and a bonding process in which the laminated processed FeCoV alloy-based thin plate is laminated and then pressure-dried to secondarily completely cure the applied adhesive. However, the laminated plates may be laminated, but are not limited thereto.

[0844] Another aspect of the present invention relates to a driving motor comprising a rotor and a stator, wherein one or more selected from the group consisting of the rotor and the stator comprise a laminate formed by laminating FeCoV alloy-based thin sheets, wherein the FeCoV alloy-based thin sheets comprise γ-austenite and residual α-ferrite, and the average grain size is 50 to 100 μm.

[0845] The driving motor according to the present invention includes a laminate comprising a FeCoV alloy-based thin sheet having an average grain size of 50 to 100 μm and containing γ-austenite and residual α-ferrite, and thus has the advantage of having excellent magnetic properties and excellent mechanical properties.

[0847] In another embodiment of the present invention, the average size of the crystal grains may be 50 to 80 μm.

[0848] In another embodiment of the present invention, the average size of the crystal grains may be 50 to 60 μm.

[0849] If the average size of the crystal grains satisfies the above range, it is desirable as it has the advantage of excellent magnetic properties.

[0851] In the present invention, the “average size of the grains” may be based on the ASTM E112 standard.

[0852] The average size of the above “grains” may refer to the overall average size of the above γ-austenite grains and the above α-ferrite grains.

[0853] The average size of the γ-austenite grains may be 50 to 100 μm, preferably 50 to 80 μm, and more preferably 50 to 60 μm.

[0855] In another embodiment of the present invention, the area fraction of the γ-austenite may be larger than the area fraction of the α-ferrite.

[0856] When the area fraction of the γ-austenite is greater than the area fraction of the α-ferrite, it means that cold rolling has been performed smoothly. As a result, the FeCoV alloy-based thin sheet has a high saturation magnetic flux density, low coercivity, and low iron loss value, which is desirable because the magnetic properties of the driving motor are excellent.

[0858] In another embodiment of the present invention, the area fraction of the γ-austenite may be 60 to 95%.

[0859] In another embodiment of the present invention, the area fraction of the α-ferrite may be 5 to 50%.

[0860] When the area fraction of the γ-austenite and the area fraction of the α-ferrite satisfy the above range, it is desirable as there is an advantage of excellent magnetic properties.

[0862] In another embodiment of the present invention, the ratio of the number of γ-austenite and α-ferrite may be 80:20 to 60:40.

[0863] Specifically, the number of the γ-austenite and α-ferrite may be based on ASTM E112 standards.

[0864] Preferably, the ratio of the number of γ-austenite and α-ferrite may be 70:30 to 60:40.

[0865] When the ratio of the number of γ-austenite and α-ferrite satisfies the above range, it is desirable as it has the advantage of excellent soft magnetic properties and excellent mechanical properties.

[0867] In another embodiment of the present invention, the number of γ-austenite grains, each having a size of 50 to 100 μm based on ASTM E112, may be 5 to 12.

[0868] Preferably, the number of the γ-austenite grains may be 7 to 10.

[0869] When the number of the above γ-austenite grains satisfies the above range, it is easy to obtain a laminate, which is desirable.

[0871] In another embodiment of the present invention, the number of α-ferrite crystal grains, each having a size of 50 to 100 μm based on ASTM E112, may be 2 to 8.

[0872] Preferably, the number of the α-ferrite grains may be 2 to 6, and more preferably 4 to 6.

[0873] It is desirable when the number of the above α-ferrite grains satisfies the above range because the mechanical properties are excellent.

[0875] The FeCoV alloy-based thin sheet according to the present invention contains γ-austenite and residual α-ferrite, and since the average grain size is 50 to 100 μm, it has the advantage of excellent mechanical performance as well as magnetic properties.

[0877] The FeCoV alloy-based thin sheet according to the present invention can be manufactured by the method for manufacturing the FeCoV alloy-based thin sheet described above.

[0878] For example, the above FeCoV alloy-based thin sheet may be manufactured by a method for manufacturing a FeCoV alloy-based thin sheet comprising, but is not limited to, the step of preparing a FeCoV alloy-based sheet material; the step of heat-treating the FeCoV alloy-based sheet material at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; the step of rapidly cooling the heat-treated FeCoV alloy-based sheet material; and the step of cold-rolling the rapidly cooled FeCoV alloy-based sheet material to obtain a FeCoV alloy-based thin sheet.

[0879] The above FeCoV alloy-based thin sheet contains γ-austenite and residual α-ferrite, and the average grain size is 50 to 100 μm.

[0880] The specific manufacturing steps of the above-mentioned method for manufacturing the FeCoV alloy-based thin sheet can be applied to the aforementioned details.

[0881] The average grain size, area fraction of γ-austenite and α-ferrite, number, etc. of the above FeCoV alloy-based thin sheet may vary depending on the heat treatment temperature during the process of manufacturing the FeCoV alloy-based thin sheet.

[0883] In another embodiment of the present invention, the total weight may be 50 kg or less, and the efficiency may be 96% or more when the motor output is 220 kW.

[0884] The drive motor according to the present invention may be a drive motor for an electric vehicle suitable for rotating at 12,000 to 28,000 rpm.

[0886] The above rotor may include a laminate formed by laminating the aforementioned FeCoV alloy-based thin sheets.

[0887] The above stator may include a laminate formed by stacking the aforementioned FeCoV alloy-based thin plates.

[0888] The rotor and stator above may include a laminate formed by laminating the aforementioned FeCoV alloy-based thin plates.

[0890] The above-described drive motor may additionally include, but is not limited to, a battery as a main power source, an inverter that converts the DC voltage supplied from the motor and the battery, a coil wound on a rotor core, an MCU that controls the voltage supply, and a current controller that supplies power from the battery to the coil.

[0892] The above FeCoV alloy-based thin sheet may be manufactured by any one of the manufacturing methods of the above-described FeCoV alloy-based thin sheet.

[0893] For example, another aspect of the present invention relates to a method for manufacturing a drive motor component comprising the steps of: preparing an FeCoV alloy-based sheet; heat-treating the FeCoV alloy-based sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated FeCoV alloy-based sheet; cold-rolling the rapidly cooled FeCoV alloy-based sheet to obtain an FeCoV alloy-based thin sheet; processing the FeCoV alloy-based thin sheet; and laminating the FeCoV alloy-based thin sheet after processing.

[0894] A driving motor component according to the present invention can be manufactured by undergoing the steps of: processing the FeCoV alloy-based thin sheet in the above-described method for manufacturing the FeCoV alloy-based thin sheet; and laminating the FeCoV alloy-based thin sheet after processing.

[0895] In short, the above FeCoV alloy-based thin sheet may be manufactured using the manufacturing method of the above-described FeCoV alloy-based thin sheet.

[0896] The specific manufacturing steps of the above method for manufacturing the FeCoV alloy-based thin sheet can be applied as described above.

[0898] The above processing step may be a step of processing multiple sheets of the FeCoV alloy-based thin plate into a core shape.

[0899] The above processing process may be performed using a laser, but is not limited thereto.

[0900] For example, the above processing process can be performed by cutting with a laser at a scanning speed of 10,000 mm / min or more to obtain a drive motor component suitable for high efficiency of the motor, but is not limited thereto.

[0902] The step of laminating the above FeCoV alloy-based thin plates may be mutually fixed using adhesives or the like, but is not limited thereto.

[0903] For example, the laminated plates may be laminated through a coating process in which an adhesive is applied to both sides of the processed FeCoV alloy-based thin plate, a drying process in which the FeCoV alloy-based thin plate with the applied adhesive is dried to first cure the applied adhesive, and a bonding process in which the laminated processed FeCoV alloy-based thin plate is laminated and then pressure-dried to secondarily completely cure the applied adhesive. However, the laminated plates may be laminated, but are not limited thereto.

[0905] Preferred embodiments and comparative examples of the present invention are described below. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0907] <Preparation Examples 1 and 2>

[0908] Preparation Example 1

[0909] Fe 49 Co 49 V2 (Psalms 1 to 6) and Fe 48.43 Co 51.11 Cr 0.46(Specimen 7) After preparing the plate, heat treatment was performed at the temperatures and times specified in Table 1 below. Subsequently, the plate was immersed in cooling water for rapid cooling (at a rate of 50℃ / sec), followed by cold rolling at a total reduction ratio of 96.7% to obtain a 0.2mm thick Fe 49 Co 49 V2 thin film and Fe 48.43 Co 51.11 Cr 0.46 A thin sheet was manufactured. In the case of specimen 1, cold rolling was performed after slow cooling without undergoing a rapid cooling step following heat treatment.

[0911] Heat treatment conditions Saturation magnetic flux density (T) Residual magnetic flux density (T) Coercivity (kA / m) Coercivity (Oe) Magnetic flux density value (T) when 5000 A / m is applied Iron loss @ 400Hz 1T W / kg Driving efficiency (T.kg / W) 850 ℃ for 1 hour (excluding rapid cooling) Psalm 1 2.3080 0.6480 0.0221 0.2778 2.1160 21.3180 0.5413 950℃ for 1 hour Psalm 2 2.1685 0.6956 0.0246 0.3086 1.9865 14.8510 0.7301 1050℃ for 1 hour Psalm 3 2.2585 1.0590 0.0197 0.2470 2.2025 13.0390 0.8661 950℃ for 15 minutes Psalm 4 2.2837 0.9953 0.0218 0.2744 2.2207 13.5263 0.8442 950℃ 30 minutes Psalm 5 2.2900 0.7487 0.0156 0.1961 2.1620 12.5185 0.9146 950℃ for 2 hours Psalm 6 2.2775 1.0036 0.0195 0.2445 2.2200 13.1020 0.8691 950℃ 1 hour Fe 48.43 -Co 51.11 -Cr 0.46 Psalm 7 2.2930 0.9985 0.0175 0.2354 2.1868 13.1720 0.8704

[0913] Preparation Example 2

[0914] Fe prepared according to Table 1 49 Co 49 Fe among V2 sheets manufactured by heat treatment at 950℃ for 30 minutes 49 Co 49 Stress relief heat treatment was performed on the V2 sheet at the temperature according to Table 2 below for 30 minutes.

[0916] Stress relief heat treatment temperature Types of Psalms Saturation magnetic flux density (T) Residual magnetic flux density (T) Coercivity (kA / m) Coercivity (Oe) Magnetic flux density value (T) when 5000 A / m is applied Iron loss @ 400Hz (1T W / kg) Driving efficiency (T.kg / W) 600℃ Psalm 8 2.13 0.98 0.052 0.708 1.87 180.46 0.059016 700℃ Psalm 9 2.236667 0.793867 0.023 0.289667 2.110667 16.81067 0.665252 800℃ Psalm 10 2.26 0.7294 0.0205 0.2605 2.117 14.736 0.76683 830℃ Psalm 11 2.215 0.5999 0.01685 0.21135 2.001 15.9815 0.692989 850℃ Psalm 12 2.223333 0.753167 0.026833 0.337427 2.020667 14.53133 0.765014 880℃ Psalm 13 2.26 0.745 0.165 2.075 1.875 41.577 0.271785 900℃ Psalm 14 2.18 0.777 0.064 0.809 1.951 31.15 0.34992

[0918] Experimental Example

[0919] The saturation magnetic flux density, residual magnetic flux density, coercivity, magnetic flux density value when 5000 A / m is applied, iron loss, and driving efficiency of the FeCoV alloy-based thin sheets manufactured according to Tables 1 and 2 were measured, and the results are shown in Tables 1 and 2 above.

[0921] (1) Iron loss

[0922] Iron loss was measured under conditions where the magnitude of the applied magnetic field was 1T and the frequency was 400Hz.

[0924] (2) Driving efficiency

[0925] The driving efficiency was measured by calculating the formula (maximum saturation flux density) / (iron loss × 0.2). Specifically, to normalize the scale value of the driving efficiency, a constant value reflecting this must be multiplied differently to the numerator and denominator, respectively, and this can be defined as the safe factor.

[0926] Here, the values ​​multiplied in the denominator and numerator must be less than 1, and the influence and range percentage of the values ​​must be taken into account. Considering that the fluidity of the saturation magnetic flux density value is about 5 times the fluidity of the iron loss value, the denominator was multiplied by 0.2 and the numerator by 1.0 to calculate the result.

[0928] (3) Elongation and tensile strength

[0929] Fe prepared by heat treatment at 950℃ for 30 minutes 49 Co 49 V2 thin sheet and Fe manufactured by subsequently performing stress relief heat treatment at 850℃ for 30 minutes 49 Co 49 The elongation and tensile strength of the V2 sheet were measured, and the results are shown in Fig. 1a (no stress relief heat treatment performed) and Fig. 1b (stress relief heat treatment performed), respectively.

[0931] (4) XRD analysis

[0932] Fe prepared by heat treatment at 950℃ for 30 minutes 49 Co 49 V2 thin sheet and Fe manufactured by subsequently performing stress relief heat treatment at 850℃ for 30 minutes 49 Co 49 The XRD analysis results of the V2 thin plate are shown in Figure 2a (stress relief heat treatment not performed) and Figure 2b (stress relief heat treatment performed), respectively.

[0934] (5) Magnetic properties

[0935] Fe prepared by heat treatment at 950℃ for 30 minutes 49 Co 49 Fe manufactured by performing stress relief heat treatment on a V2 sheet at 850℃ for 30 minutes49 Co 49 The change in iron loss value at 5000 A / m magnetic flux density and 1 T applied at 400 Hz of V2 thin plate is shown in Figures 3a and 3b.

[0937] Referring to Table 1, it can be seen that specimens heat-treated for a certain period of time in a specific temperature range exhibit high saturation magnetic flux density values ​​and low iron loss values. Specifically, it can be seen that the saturation magnetic flux density value varies slightly depending on the heat treatment temperature of the specimen, and that the magnetic flux density value in a specific range (5000 A / m) also varies in preparation for use as an electric vehicle motor.

[0939] Referring to Figures 1a and 1b, it can be seen that the mechanical properties differ slightly before and after stress relief heat treatment. In the present invention, the most appropriate heat treatment condition is determined to be one that simultaneously satisfies conditions for mechanical properties and magnetic properties, particularly high saturation magnetic flux density and low iron loss. It can be seen that when compared with magnetic property values, the magnetic and mechanical properties are best under heat treatment conditions at a specific temperature.

[0940] Referring to Figures 2a and 2b, there were differences in peak width and height between the specimens before and after stress relief heat treatment, but the 2theta positions where the peaks were formed were almost identical. This implies that they are composed of the same phase, and it is understood that rather than a new phase being created through heat treatment, the level of regularity of the formed phase changed from a disordered structure to an ordered structure. It is believed that cold rolling is possible due to the irregular structure formed before cold rolling, and that during the stress relief process after rolling, a room-temperature stable phase is formed to ensure regularity, thereby improving not only mechanical properties but also magnetic properties.

[0941] Referring to Figures 3a and 3b, it can be seen that the specimen subjected to stress relief heat treatment exhibits a high saturation magnetic flux density value (2.26T) and a low iron loss value (14.248W / kg), which is comparable to the soft magnetic thin sheet (Fe) manufactured through conventional complex processes. 49 Co 49 It was confirmed that it showed a level similar to V2).

[0943] <Preparation Example 3>

[0944] Fe 49 Co 49 After preparing V2 plates, heat treatments were performed at 950°C for 1 hour and at 1100°C for 1 hour, respectively. Subsequently, the plates were immersed in cooling water for rapid cooling (at a rate of 50 / sec), followed by cold rolling at a total reduction ratio of 96.7% to produce Fe with a thickness of 0.2 mm. 49 Co 49 V2 thin plates were manufactured.

[0946] Experimental Example

[0947] Figure 4 shows an image of the cross-section of a specimen prepared by heat-treating at 950°C for 1 hour during the preparation process of Preparation Example 3, measured using a scanning electron microscope (SEM: JEOL 7600F).

[0948] In addition, Fe prepared by heat treatment at 950℃ and 1100℃ for 1 hour 49 Co 49 The lateral cross-sectional structure of the V2 sheet was imaged using an optical microscope (OM: olympus DSX500) and compared under different conditions, and the results are shown in Figures 5 to 7 (Figures 5 and 7: specimens heat-treated at 950°C, Figure 6: specimens heat-treated at 1100°C).

[0950] Referring to Figure 4, it can be seen that a composite phase is formed in which the γ-austenite phase is distributed throughout and some residual α-ferrite phase is included.

[0951] In addition, it was confirmed that cold rolling proceeded smoothly without cracking or bursting when cold rolling was performed, and the side of the thin sheet rolled to a thickness of 0.2 mm had a uniform pattern of lines, which proves that the cold rolling process was carried out smoothly.

[0952] Referring to FIGS. 4 to 7, it was confirmed that the microstructure quenched under appropriate conditions consists mostly of elongable γ-austenite phase and exhibits a composite microstructure in which some α-ferrite phase coexists, and the microstructure of the cross-section has a stripe structure, with the spacing being approximately 1 to 3 μm.

[0954] <Preparation Example 4>

[0955] A FeCoV alloy molten metal was prepared by melting iron alloy components at a temperature of 1700°C using a vacuum melting method. The alloy molten metal was poured into a mold and cooled and crystallized at a casting speed of 75 mm / min to produce an ingot (Fe49Co49V2, Fe 47.79, Co 50.43, V 1.78 wt%: weight ratio).

[0956] The manufactured ingot was cut to a thickness of 30 mm and then hot-rolled using a steel rolling mill to obtain a plate. At this time, the rolling start temperature was 950°C and the rolling end temperature was 1150°C, and the process was carried out with 5 passes at a total reduction rate of 80% to achieve a final thickness of approximately 6 mm.

[0957] The obtained plate was subsequently heat-treated at 950°C and 1100°C for 1 hour each. Afterward, it was rapidly cooled (at a rate of 50°C / sec) by immersion in cooling water, followed by cold rolling at a total reduction ratio of 96.7% to obtain Fe with a thickness of 0.2 mm. 49 Co 49 V2 thin plates were manufactured.

[0959] Experimental Example

[0960] (1) XRD measurement

[0961] According to Preparation Example 4, Fe 49 Co 49 The XRD patterns of the cast ingot produced during the process of manufacturing V2 thin sheets, the specimen before heat treatment (after hot rolling), and the specimen after heat treatment at 950°C and rapid cooling (after cold rolling) were compared and are shown in Figures 8a to 8c, respectively. XRD: Using the equipment model name (DMAX2500), XRD diffraction patterns were obtained in the 2theta value range of 10 to 100°, and then qualitative and quantitative analysis was performed.

[0963] (2) Organizational comparison

[0964] According to Preparation Example 4, Fe 49 Co 49 Images were measured using a scanning electron microscope (SEM: model name JEOL 7600F) of a cast ingot produced during the process of manufacturing V2 thin sheets, a specimen after heat treatment at 950°C and 1100°C and quenching (after cold rolling), and then grain size and phase analysis were performed, and the results are shown in Figures 9a to 9c, respectively.

[0966] (3) GDS surface analysis

[0967] According to Preparation Example 4, Fe 49 Co 49 In the process of manufacturing the V2 thin sheet, the specimen prior to heat treatment (after hot rolling) and Fe prepared in the same manner as Preparation Example 4 by changing the heat treatment temperature to 700℃, 850℃, and 900℃ 49 Co 49 The specimens of the V2 thin plate were analyzed using a GDS surface analysis system, and the results are shown in Figures 10a to 10d, respectively.

[0968] Specifically, specimens were prepared for each, and surface analysis was performed by cutting away the surface from the surface of the plate or thin plate in the depth direction. The experimental conditions are as follows.

[0969] <Experimental Conditions>

[0970] Method: Zn Galv RF

[0971] Lamp type: RF (Radio frequency)

[0972] Analysis area: 4mФ

[0973] Calibration factor: 0.70

[0974] Analysis conditions:700V, 30mA, 21W

[0975] Depth setting: 0~end sec, 100points / sec

[0976] Plot point: 8000, Smoothing:3

[0978] Referring to Figures 8a to 8c, XRD analysis of the cast ingot revealed only a single phase, namely the Fe phase, whereas the specimen prior to heat treatment (after hot rolling) showed many oxide phase peaks in addition to the Fe single phase. In particular, some oxides were present even after the rapid cooling heat treatment that changed the α-ferrite structure to the γ-austenite structure. The most important point is that as the α-ferrite structure changes to the γ-austenite structure, the height and Full Width Half Maximum (FWHM) of the existing α peak change in the XRD image, and a γ peak that was not previously visible is discovered.

[0979] In addition, in the same Fe-α peak, for the cast ingot, the (100) plane appears at around 45 degrees, the (200) peak at around 60 degrees, and the (211) peak at around 85 degrees.

[0980] Here, in the casting ingot, that is, in the material with a completely regular structure due to slow cooling, the (100) plane peak rises the highest and the others are relatively very low, whereas in the specimen before heat treatment (after hot rolling) and the sample after heat treatment and rapid cooling (after cold rolling), the peak of the main peak (100) plane decreases, while the height of the (211) plane peak increases significantly. From this, it can be confirmed that even with the same structure, the regular structure can become an irregular structure or the irregular structure can become regular depending on the process or heat treatment.

[0981] Referring to Figures 9a to 9c, in the case of a cast ingot, the grain boundaries are distinct and coarse grain boundaries of 100 to 500 μm are exhibited, whereas in the case of a specimen that has undergone high-temperature heat treatment and rapid cooling, depending on the conditions, it may contain both fine and coarse structures or contain fine grains of approximately 100 μm, and the occurrence of defects during the cold rolling process may be determined by these differences in structure and crystal structure.

[0982] Meanwhile, surface analysis was performed using GDS analysis equipment to observe changes in the plate-like surface prior to heat treatment and during heat treatment at each temperature condition.

[0983] Although oxygen and carbon were hardly detected on the surface of the plate that was not heat-treated, as the heat treatment temperature increased, surface oxygen and carbon components were detected up to a depth of 0.1 to 0.2 μm, and the phase fractions of Fe and Co were also quantitatively distributed almost equally as the heat treatment temperature increased and as they penetrated in the depth direction.

[0984] Since the steel plate used in the experiment is composed of 49Fe-49Co-2V, when V element is dissolved and then precipitates form as the heat treatment temperature increases, causing precipitation hardening, the quantitative ratio of Co and Fe elements becomes nearly equal. Therefore, according to the results of the depth profile analysis above, it is estimated that a precipitate of V element is formed under heat treatment temperature conditions of 880 degrees or higher.

[0986] <Preparation Example 5>

[0987] A FeCoV alloy molten metal was prepared by melting iron alloy components at a temperature of 1700°C using a vacuum melting method. The alloy molten metal was poured into a mold and cooled and crystallized at a casting speed of 75 mm / min to produce an ingot (Fe49Co49V2, Fe 47.79, Co 50.43, V 1.78 wt%: weight ratio).

[0988] The manufactured ingot was cut to a thickness of 30 mm and then hot-rolled using a steel rolling mill to obtain a plate. At this time, the rolling start temperature was 950°C and the rolling end temperature was 1150°C, and the process was carried out with 5 passes at a total reduction rate of 80% to achieve a final thickness of approximately 6 mm.

[0989] The obtained plate was then heat-treated at 950°C for 30 minutes. Afterward, it was rapidly cooled (at a rate of 50°C / sec) by immersion in cooling water, followed by cold rolling with a total reduction ratio of 96.7% to obtain Fe with a thickness of 0.2 mm. 49 Co 49 A V2 thin sheet was manufactured. Afterwards, an annealing heat treatment was performed at a temperature of 950 ℃ for 30 minutes.

[0991] Experimental Example

[0992] (1) XRD measurement

[0993] According to Preparation Example 5, Fe 49 Co 49Figures 11a and 11b compare the XRD patterns of specimen #1 (before annealing heat treatment) immediately after cold rolling and specimen #2 (after annealing heat treatment) manufactured during the process of manufacturing V2 thin sheets, and the strength and half-width are shown in Table 3 below.

[0995] Psalm number Location(°) Norm.Intensity FWHM(°) #1 21.2627 34.56 4.5234 44.541 296.41 0.6394 64.9505 2480.89 0.6309 82.3662 1195.02 0.7229 #2 44.695 29.68 0.3597 65.0915 5904.41 0.0811 82.4635 36456.7 0.0865

[0997] (2) Measurement of investment rate

[0998] The hysteresis of specimens #1 and #2 was measured, and the results are shown in Fig. 12.

[1000] Referring to Figures 11a and 11b and Table 3 above, specimen #1 exhibits a typical preferred orientation with decreasing intensity over a very wide area, whereas specimen #2 shows multiple peaks in the Rocking curve, which can occur when grains such as very well-aligned single crystals are arranged in multiple directions.

[1001] In other words, in terms of crystallinity (or ordering), comparing specimens #1 and #2—that is, specimens immediately after cold rolling and immediately after annealing—it implies that specimen #2 has a very superior degree of crystallinity when predicted based on the major plane of the peaks and the full width at half maximum (FWHM).

[1002] This is because the microstructure prior to heat treatment has an ordering structure due to slow cooling in the previous process and consists of an α-ferrite phase in the form of a body-centered cubic (BCC) structure, which can cause problems in the cold rolling process due to its relatively low elongation.

[1003] Therefore, a heat treatment process was performed to transform the structure into a γ-austenite phase with a face-centered cubic (FCC) structure while forming a disordered or ordering-disordering mixed structure through microstructure control heat treatment. Since the structure must be ordered again after cold rolling to increase magnetic properties, such as saturation magnetic flux density and iron loss, the changes in XRD before and after heat treatment were compared.

[1004] When measuring the magnetic properties of specimen #1, which was not subjected to stress relief heat treatment after cold rolling, and specimen #2, which was subjected to stress relief heat treatment, the results are as shown in the graph of Fig. 12. There were very large differences in soft magnetic properties, such as the slope of the hysteresis graph, the internal area, and the magnetic flux density value in the same frequency range.

[1006] <Preparation Example 6>

[1007] The iron alloy composition according to Table 4 was melted at a temperature of 1700°C using a vacuum melting method to prepare a FeCoV alloy molten metal. The alloy molten metal was poured into a mold and cooled and crystallized at a casting speed of 75 mm / min to produce an ingot.

[1008] The manufactured ingot was cut to a thickness of 30 mm and then hot-rolled using a steel rolling mill to obtain a plate. At this time, the rolling start temperature was 950°C and the rolling end temperature was 1150°C, and the process was carried out with 5 passes at a total reduction rate of 80% to achieve a final thickness of approximately 6 mm.

[1009] Afterward, the obtained sheet was heat-treated at 950°C for 30 minutes. Then, it was immersed in cooling water and rapidly cooled (at a rate of 50°C / sec), and then cold-rolled with a total reduction rate of 96.7% to produce a 0.2 mm thick FeCoV alloy-based thin sheet, and then the soft magnetic performance was measured.

[1011] Alloy composition (at%, atomic ratio) Saturation magnetic flux density (Bs) / T Coercivity (H2.04e / Oe) Fe Co V Ni Cr Nb 49 49 2 - - - 2.38 0.18 55 35 1 8 1 - 2.04 33.12 58 25 2 12 3 - 1.99 43.43 60 20 2 15 2 1 1.96 23.27 63 20 1 15 1 - 2.01 26.15 66 20 2 10 1 1 2.04 42.06

[1013] <Preparation Examples 7 and 8>

[1014] Preparation Example 7

[1015] A FeCoV alloy molten metal was prepared by melting iron alloy components at a temperature of 1700°C using a vacuum melting method. The alloy molten metal was poured into a mold and cooled and crystallized at a casting speed of 75 mm / min to produce an ingot (Fe49Co49V2, Fe 47.79, Co 50.43, V 1.78 wt%: weight ratio).

[1016] The manufactured ingot was cut to a thickness of 30 mm and then hot-rolled using a steel rolling mill to obtain a plate. At this time, the rolling start temperature was 950°C and the rolling end temperature was 1150°C, and the process was carried out with 5 passes at a total reduction rate of 80% to achieve a final thickness of approximately 6 mm.

[1017] The obtained plate was subsequently heat-treated at 950°C and 1100°C for 1 hour each. Afterward, it was rapidly cooled (at a rate of 50°C / sec) by immersion in cooling water, followed by cold rolling at a total reduction ratio of 96.7% to obtain Fe with a thickness of 0.2 mm. 49 Co 49 V2 thin plates were manufactured.

[1019] Preparation Example 8

[1020] A FeCoV alloy molten metal was prepared by melting iron alloy components at a temperature of 1700°C using a vacuum melting method. The alloy molten metal was poured into a mold and cooled and crystallized at a casting speed of 75 mm / min to produce an ingot (Fe49Co49V2, Fe 47.79, Co 50.43, V 1.78 wt%: weight ratio). At this time, the alloy molten metal was melted under argon gas. The produced ingot was cut to a thickness of 6 mm to produce a casting material.

[1021] Subsequently, the casting was heat-treated at 950°C and 1100°C for 2 hours each, rapidly cooled by immersion in cooling water (at a rate of 50°C / sec), and then cold-rolled with a total reduction ratio of 96.7% to produce Fe with a thickness of 0.2 mm. 49 Co 49 V2 thin plates were manufactured.

[1023] Experimental Example

[1024] (1) XRD measurement

[1025] According to Preparation Example 7, Fe 49 Co 49 A cast ingot produced during the process of manufacturing V2 thin sheets (Specimen 1), a specimen immediately after hot rolling (before heat treatment) (Specimen 2), a specimen after heat treatment at 950°C and rapid cooling (after cold rolling, Specimen 3), and Fe according to Preparation Example 8 49 Co 49 After obtaining an XRD diffraction pattern with a 2theta value in the range of 10 to 100 degrees using an XRD (model name DMAX2500) equipment on a specimen (specimen 4) that had been heat-treated and rapidly cooled at 950°C during the process of manufacturing V2 thin plates, qualitative and quantitative analysis were performed, and the results are shown in Figures 13a to 13d, respectively.

[1027] (2) Organizational comparison

[1028] According to Preparation Example 7, Fe 49 Co 49 Cast ingot produced during the process of manufacturing V2 thin sheets (Specimen 5), specimens after heat treatment at 1100°C and 950°C immediately after hot rolling and rapid cooling (after cold rolling, Specimens 6 and 7, respectively), and Fe according to Preparation Example 8 49 Co 49 Specimens (specimens 8 and 9, respectively) produced during the process of manufacturing V2 thin sheets after heat treatment and rapid cooling at 1100°C and 950°C were imaged using a scanning electron microscope (SEM: model name JEOL 7600F), and the results are shown in Figures 14a to 14e.

[1030] (3) Evaluation of soft magnetic performance

[1031] Fe prepared by performing heat treatment at 950°C in Preparation Examples 7 and 8 49 Co 49 The soft magnetic performance of the V2 sheet was evaluated, and the results are shown in Table 5 below.

[1033] Saturation magnetic flux density (T) Coercivity (Oe) Magnetic flux density value (T) when 5000 A / m is applied Cores @ 400Hz 1T W / kg Manufacturing Example 7 (Hot Rolling + Cold Rolling) 2.318 0.163 2.184 12.565 Manufacturing Example 8 (Cold Rolling) 2.202 0.229 2.031 17.591

[1035] Referring to FIGS. 13a to 13d, 14a to 14e and Table 5, it can be seen that the thin sheet manufactured from the FeCoV alloy-based thin sheet according to the present invention has a high saturation magnetic flux density, low coercivity, and iron loss (core loss) value even without hot rolling.

[1037] <Preparation Example 9>

[1038] FeCoV alloy-based sheets were heat-treated at 950°C and 1100°C for 1 hour each. Afterward, they were rapidly cooled (at a rate of 50°C / sec) by immersion in cooling water, followed by cold rolling at a total reduction rate of 96.7% to obtain Fe with a thickness of 0.2 mm. 49 Co 49 V2 thin plates were manufactured.

[1040] Experimental Example

[1041] (1) Organization comparison

[1042] Fe prepared according to Preparation Example 9 49 Co 49 After measuring images of the V2 thin plate using a scanning electron microscope (SEM: model name JEOL 7600F), the results are shown in Figures 15a and 15b.

[1044] (2) Number of grains and textures

[1045] Fe prepared according to Preparation Example 9 49 Co 49 The grain size, γ-austenite phase, and α-ferrite phase of the V2 sheet were observed and measured according to ASTM E112 standards, and the results are shown in Table 6 below.

[1047] Average grain size Area fraction of γ-austenite Area fraction of α-ferrite Number of γ-austenites Number of α-ferrites Ratio of the number of γ-austenite phases in the total structure Heat treatment temperature 1100℃ 263.4 27 73 2.2 6.8 24 % Heat treatment temperature 950 ℃ 57.2 63.7 36.3 8.9 5.4 62 %112

[1049] (3) Soft magnetic properties

[1050] Fe prepared according to Preparation Example 9 49 Co 49 The soft magnetic properties of the V2 sheet were measured, and the results are shown in Table 7 below.

[1052] Saturation magnetic flux density (T) Coercivity (Oe) Magnetic flux density value (T) when 5000 A / m is applied Cores @ 400Hz 1T W / kg Heat treatment temperature 1100℃ 2.115 0.198 2.019 14.479 Heat treatment temperature 950 ℃ 2.318 0.163 2.184 12.565

[1054] Referring to Figures 15a and 15b, it can be seen that the relatively bright part is the γ-austenite phase and the relatively dark part is the α-ferrite phase, representing a composite phase including the γ-austenite phase and the α-ferrite phase.

[1055] Referring to Table 7 above, it can be seen that the FeCoV alloy-based thin sheet according to the present invention has a high saturation magnetic flux density and has low coercivity and core loss values.

[1057] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

Claim 1 A method for manufacturing a FeCoV alloy thin sheet, comprising the steps of: preparing a FeCoV alloy molten metal; casting the alloy molten metal to produce an ingot; hot rolling the ingot to obtain a sheet; heat treating the sheet at 600 to 1200°C for 10 to 240 minutes to change at least a portion of the α-ferrite phase into a γ-austenite phase; rapidly cooling the heat-treated sheet; and cold rolling the rapidly cooled sheet to obtain a FeCoV alloy thin sheet; wherein the FeCoV alloy thin sheet is such that the intensity of the peak of the (100) plane among the peaks of the X-ray diffraction pattern of the ingot is reduced or does not appear. Claim 2 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the intensity of the peak of the (211) plane among the peaks of the X-ray diffraction pattern of the ingot is increased. Claim 3 A method for manufacturing a FeCoV alloy-based thin sheet, wherein, in claim 1, the intensity of the peak of the (100) plane among the peaks of the X-ray diffraction pattern of the hot-rolled sheet material is reduced or does not appear. Claim 4 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the FeCoV alloy-based thin sheet has an increased intensity of the peak of the (211) plane among the peaks of the hot-rolled X-ray diffraction pattern. Claim 5 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the FeCoV alloy-based thin sheet contains at least 50% more crystal grains of 150 μm or less than the ingot. Claim 6 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the difference between the area occupied by cobalt and the area occupied by iron within the region up to 35 μm from the surface of the FeCoV alloy-based thin sheet on the GDS depth profile is smaller than the difference between the area occupied by cobalt and the area occupied by iron within the region up to 35 μm from the surface of the hot-rolled sheet. Claim 7 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the FeCoV alloy-based thin sheet has an impurity content in a region up to 5 μm from the surface of the FeCoV alloy-based thin sheet on a GDS depth profile that is less than the impurity content in a region up to 5 μm from the surface of the hot-rolled sheet. Claim 8 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the step of preparing the alloy molten metal includes the step of vacuum melting an alloy component composed of 20 to 49 at% cobalt, 2 to 5 at% vanadium, and the remainder being iron and other impurities. Claim 9 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the heat treatment is performed at 730 to 1200℃. Claim 10 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 9, wherein the heat treatment is performed at 840 to 1200℃. Claim 11 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the heat treatment is performed for 30 to 240 minutes. Claim 12 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the heat treatment is performed under a vacuum or inert gas atmosphere. Claim 13 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, further comprising the step of obtaining the FeCoV alloy-based thin sheet; and subsequently the step of performing stress relief heat treatment on the FeCoV alloy-based thin sheet. Claim 14 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 13, wherein the stress relief heat treatment is performed at 650 to 950°C for 10 to 120 minutes. Claim 15 A method for manufacturing a FeCoV alloy-based thin sheet according to claim 1, wherein the rapid cooling is performed at a cooling rate of 10 to 300℃ / sec.

Images