Iron-based amorphous alloy strip and method for preparing same

Abstract

The present invention provides an iron-based amorphous alloy strip and a method for preparing the same. The iron-based amorphous alloy strip is made of Fe a Si b B c C d The iron-based amorphous alloy strip has a chemical composition of 80.4%≦a≦83.5%, 3.98%≦b≦9.5%, 9.58%≦c≦12.0%, 0.1%≦d≦1.3%, and 99.9%≦a+b+c+d≦100%, where a, b, c, and d represent the atomic percentages of the corresponding components, respectively, and are 80.4%≦a≦83.5%, 3.98%≦b≦9.5%, 9.58%≦c≦12.0%, 0.1%≦d≦1.3%, and 99.9%≦a+b+c+d≦100%, with the remainder consisting of unavoidable impurities. By controlling the composition, the present invention achieves uniform cooling even under high cooling intensity, resulting in an iron-based amorphous alloy strip with high saturation magnetic induction, high glass-forming ability, and cooling uniformity. The iron-based amorphous alloy strip exhibits excellent soft magnetic properties, ensuring its quality when applied to downstream products such as transformers.

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to Chinese Patent Application No. 2022116353760, filed on December 19, 2022, entitled "Iron-based amorphous alloy strip and manufacturing method thereof," which is incorporated herein by reference in its entirety.

[0002] The present invention relates to the field of power electronics, and in particular to an iron-based amorphous alloy strip and a method for preparing the same. [Background technology]

[0003] Iron-based amorphous alloys, which exhibit magnetic anisotropy due to their unique microstructure, are widely used in the manufacture of transformer cores. Typically, when molten metal is slowly cooled from its liquid state, crystallization occurs below the liquidus. In contrast, amorphous alloys are formed by varying the cooling rate of molten metal, causing it to solidify before the atoms have completely diffused and rearranged, thereby maintaining a liquid-like disordered state. Therefore, amorphous alloys have the advantages of a low magnetic anisotropy parameter (K) and low no-load loss, making them promising candidates for completely replacing silicon steel.

[0004] With the rapid development of the power electronics industry in recent years, new goals such as "Smart 5G" and "High Energy Efficiency" are driving the development of amorphous transformers toward "miniaturization" and "low loss." As a result, alloy systems with high saturation magnetic induction have been continuously developed, especially those with high Fe content. It is well known that Fe functions as a magnetic element in compositional systems. High-Fe-content alloys have a relatively high saturation magnetic induction (Bs > 1.60 T) and therefore poor glass-forming ability. Therefore, producing fully amorphous quenched alloy strip requires high cooling rates. This results in the strip freezing before the internal stresses are released, resulting in large residual quenching stresses, leading to problems such as warping on both sides of the strip and increased loss. In particular, there is a solid-liquid equilibrium region at the cooling interface between the molten steel and the crystallizer, within which the uncooled liquid phase is called the "molten pool." The cooling capacity differs between the sides and the center of the molten pool, with the cooling intensity on both sides being higher than that in the center. This is because the two sides of the molten pool are subject to the "laminar flow" effect, which causes different energies at the edges and center of the strip on the crystallizer, resulting in a temperature difference between the center and both sides of the strip as it peels off the crystallizer surface. Furthermore, this phenomenon becomes more pronounced as the width of the strip increases, making it difficult to manufacture wide-width amorphous strip and causing problems such as breakage and unstable performance. Microscopically, the difference in cooling intensity between the two sides and the center of the strip generates transverse tensile stress within the strip, ultimately leading to reduced strip performance. Furthermore, when unevenly cooled materials are used to manufacture transformer cores for back-end applications, they can suffer from poor thermal stability. This can lead to problems such as high core excitation power and increased noise, especially if stress is not completely removed.

[0005] Many researchers have also investigated the uneven cooling phenomenon in the crystallizer and molten pool caused by the high cooling intensity of the above alloy systems with high saturation magnetic induction. U.S. Patent No. 5,456,770 reports that the addition of Sn improves the ductility of strip and the formability of wide strips, but the addition of Sn significantly increases costs and fails to meet industrial production requirements. Chinese Patent No. 113,151,750 identifies the problem of transverse warping in strip production using high saturation magnetic induction alloy systems. Strips produced by controlling trace elements in the molten steel and manipulating process parameters still suffer from transverse warping, and this problem has yet to be fundamentally resolved. Other researchers have conducted a series of experiments on the structure of crystallizers. For example, Chinese Patent No. 114,381,673 achieves neutralization of the cooling intensity between the center and both sides of the crystallizer by adjusting the internal water channels of the crystallizer along the strip's width. However, this method is adjusted from the viewpoint of heat transfer, and although it can achieve uniform cooling in the center and both sides of the strip, corresponding adjustments are required for strips of different widths. Not only is the cost high, but the process is also very complicated, making it difficult to apply to industrial production. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Chinese Patent Application No. 2022116353760 [Patent Document 2] U.S. Patent No. 5,456,770 [Patent Document 3] Chinese Patent No. 113151750 [Patent Document 4] Chinese Patent No. 114381673 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides an iron-based amorphous alloy strip and a method for preparing the same, which can be used to solve the drawback of non-uniform cooling of amorphous alloy systems with high saturation induction in the prior art.

[0008] Fe a Si b B c C d The present invention provides an iron-based amorphous alloy strip having a chemical composition of: where a, b, c, and d represent the atomic percentages of the corresponding elements, and are 80.4%≦a≦83.5%, 3.98%≦b≦9.5%, 9.58%≦c≦12.0%, 0.1%≦d≦1.3%, and 99.9%≦a+b+c+d≦100%, and the remainder being unavoidable impurities.

[0009] This application focuses primarily on the design of improved compositions for the FeSiBC system, the most common in industry. While annealing induces the formation of nanoscale crystal grains to enhance saturation magnetic induction in other systems, such as FeSiBCu and FeSiBPCu, increasing the Fe content is essential for improving saturation magnetic induction in the FeSiBC system. However, alloy compositions with a high Fe content exhibit a significant decrease in glass-forming ability, placing increasingly stringent requirements on cooling capacity. High cooling intensity exacerbates the cooling differential between the sides and center of the molten pool, leading to a deterioration in the soft magnetic properties of the strip, reduced performance at the application end of the transformer core, and even instability in the heat treatment temperature of the transformer core. [Means for solving the problem]

[0010] In order to solve the above problems, an object of the present invention is to obtain an iron-based amorphous alloy strip that can be cooled uniformly even under high cooling intensity by adjusting the composition, and that has high saturation magnetic induction, high glass-forming ability, and cooling uniformity.

[0011] According to the iron-based amorphous alloy strip provided in the present application, the iron-based amorphous alloy strip has a saturation magnetic induction of 1.6 T or more. The high saturation magnetic induction strength in the present application refers to a saturation magnetic induction strength not less than 1.6 T.

[0012] According to the iron-based amorphous alloy strip provided in this application, Fe is present in an atomic percentage of 81.3%≦a≦83.5%.

[0013] According to the iron-based amorphous alloy strip provided in the present application, Si is present in an atomic percentage of 5.62%≦b≦9.5%.

[0014] In the iron-based amorphous alloy strip provided herein, Fe is present in an atomic percentage of 82.63%, Si is present in an atomic percentage of 5.62%, B is present in an atomic percentage of 10.37%, and C is present in an atomic percentage of 1.28%.

[0015] According to the iron-based amorphous alloy strip provided in the present application, the iron-based amorphous alloy strip has a specific heat capacity at 100°C of 0.40 to 0.47 J / (g·°C).

[0016] According to the iron-based amorphous alloy strip provided in the present application, the iron-based amorphous alloy strip is divided into n equal zones along its width, with the end zones occupying 10% of the strip width designated as zone a and the central zone occupying 10% of the strip width designated as zone b. For samples taken within zone a and zone b, respectively, the first crystallization peak areas are detected using a differential scanning calorimeter to obtain the calorific values ​​Qa and Qb, and the coefficient of variation δQ = (Qa - Qb) / Qa * 100% of the iron-based amorphous alloy strip is 4% or less. This performance index proves that the iron-based amorphous alloy strip of the present application exhibits cooling uniformity.

[0017] The iron-based amorphous alloy strip provided in the present application has a thickness of about 25±3 μm and a width of 30 to 300 mm, and can be used in the field of power electronics such as transformers and automobile motors.

[0018] The present invention also provides a method for producing a compound comprising: a Si b B c C d and melting the blended raw materials and single-roller quenching the blended raw materials to obtain the iron-based amorphous alloy strip.

[0019] In this method, melting is carried out using a medium frequency induction furnace, and raw materials are melted into molten steel in an atmospheric environment.

[0020] Furthermore, in the single-roll quenching process, molten steel is dropped onto the surface of a rapidly rotating copper roll. The casting temperature of the molten steel is 1400 to 1465°C, the linear velocity of the copper roll is 19 to 25 m / s, and a cooling water channel is provided inside the copper roll, through which a flow rate of 100 to 300 m 3 / h of cooling water is supplied.

[0021] According to the preparation method of the iron-based amorphous alloy strip provided in the present application, after heat treatment, the iron-based amorphous alloy strip has a core loss P≦0.2 W / kg and an excitation power Pe≦0.33 VA / kg under the conditions of 1.3 T and 60 Hz, and the core loss and excitation power of the strip can be measured using a silicon steel tester (BH tester).

[0022] The present invention provides an iron-based amorphous alloy strip and a preparation method thereof, which realizes uniform cooling even under high cooling intensity by controlling the composition, thereby obtaining an iron-based amorphous alloy strip with high saturation magnetic induction, high glass-forming ability, and uniform cooling. The iron-based amorphous alloy strip exhibits excellent soft magnetic properties, ensuring the quality of its application to downstream products such as transformers.

[0023] (Detailed explanation) In order to clarify the objectives, technical solutions and advantages of the present application, the following embodiments of the present application are clearly and completely described. Of course, the embodiments are described as examples and are not exhaustive. Based on the embodiments of the present application, all other embodiments that can be obtained by those skilled in the art without any inventive efforts fall within the scope of protection of the present application.

[0024] One aspect of the present application is Fe a Si b B c C d The present invention provides an iron-based amorphous alloy strip having a chemical composition of: where a, b, c, and d represent the atomic percentages of the corresponding elements, and are 80.4%≦a≦83.5%, 3.98%≦b≦9.5%, 9.58%≦c≦12.0%, 0.1%≦d≦1.3%, and 99.9%≦a+b+c+d≦100%, and the remainder being unavoidable impurities.

[0025] The present invention provides an iron-based amorphous alloy strip with high saturation magnetic induction, high glass-forming ability, and cooling uniformity by controlling the composition. The iron-based amorphous alloy strip of the present invention has a saturation magnetic induction strength of 1.6 T or more. The cooling uniformity is characterized by the coefficient of variation δQ of the iron-based amorphous alloy strip, δQ=(Qa-Qb) / Qa*100%, and the specific analysis is as follows:

[0026] When industrially manufacturing amorphous strips with widths ranging from 30 mm to 240 mm, the width of the molten pool increases as the strip width increases, resulting in a more pronounced difference in cooling intensity between the ends of the molten pool and the innermost center. This results in a cooling imbalance across the strip's width. That is, the sides of the strip exhibit stronger cooling capacity, resulting in a lower temperature during solidification in the molten pool. Meanwhile, the innermost center of the strip experiences a higher temperature during solidification due to the cooling imbalance. In severe cases, transverse tensile stress occurs across the strip's width, causing the strip to warp transversely. The applicant conducted sample collection and testing of strips in the above-described condition. The results of differential scanning calorimetry tests showed that when strips sampled from different positions were heated, crystallization peaks of different magnitudes appeared at the same temperature. The corresponding first crystallization peak area (i.e., the calorific value Q) was measured using software. It was observed that the Q values ​​of the strip samples from the center of the molten pool were generally lower than those of the strip samples from both sides of the molten pool. This indicates that the strips located on both sides of the molten pool retain more freezing energy as they cool, while the strips located in the center of the molten pool retain less freezing energy as they cool. Therefore, when the strips solidify, the strip temperature in the center is higher than that on the sides.

[0027] Research has shown that the energy exchange in the weld pool is achieved by heat exchange between the copper roller surface and the molten steel when they come into contact. For strips of the same width and thickness, the size and shape of the weld pool are constant, and the total amount of heat removed from the weld pool can be expressed as: ρ V c ΔT=Q total

[0028] In the above formula, ρ represents the density of the molten steel being cooled, and its unit is g / cm 3 V is the volume of molten steel in the molten pool, and its unit is cm 3c represents the specific heat capacity of the melt being cooled at that temperature, in units of J / (g·℃). ΔT represents the temperature difference between before and after cooling of the melt, in units of ℃. Q total represents the total heat exchange rate throughout the cooling process, expressed in J.

[0029] If the microelement region at the outermost edge of the weld pool width is called zone a and the microelement region at the center of the innermost weld pool is called zone b, the initial temperature of the molten steel before cooling, T initial Assuming that is uniform throughout the molten pool, then Ta initial =Tb initial Then, using Ta and Tb as the temperatures at which the strip is cooled to a solid, DSC is used to detect the magnitude of the first crystallization peak area of ​​the strip sample in zone a and zone b, i.e., the values ​​of Qa and Qb.

[0030] In a specific embodiment of the present invention, an iron-based amorphous alloy strip is divided into n equal zones along its width, with the end zones accounting for 10% of the strip width being zone a and the central zone accounting for 10% of the strip width being zone b. For samples taken within zone a and zone b, respectively, the first crystallization peak areas are detected using a differential scanning calorimeter to determine the calorific values ​​Qa and Qb. The coefficient of variation of the iron-based amorphous alloy strip is δQ = (Qa - Qb) / Qa * 100%. When δQ is 4% or less, the iron-based amorphous alloy strip of the present invention exhibits good cooling uniformity.

[0031] Specifically, Fe functions as a magnetic element in the alloy composition, and its content directly affects the saturation magnetic induction of the alloy. Generally, the higher the Fe content, the higher the saturation magnetic induction of the alloy. However, increasing the Fe content requires reducing the content of other amorphous elements, which reduces the glass-forming ability of the alloy composition and increases the manufacturing difficulty. In this application, the atomic percentage of Fe is 80.4 to 83.5%. Specifically, the atomic percentage of Fe may be, but is not limited to, 80.40%, 80.54%, 80.61%, 80.75%, 82.63%, 83.2%, or 83.5%. If the atomic percentage of Fe exceeds 83.5%, the glass-forming ability will be significantly reduced and the soft magnetic properties will also deteriorate. Conversely, if the atomic percentage of Fe is less than 80.40%, although manufacturing will proceed smoothly, the saturation magnetic induction strength of the alloy will be below 1.60 T, which does not meet the requirement for high saturation magnetic induction.

[0032] As an amorphous-forming element, Si primarily functions to enhance the glass-forming ability of alloys. Molten steel containing Si is easily oxidized during atmospheric melting, forming a dense oxide film that adheres closely to the surface of the molten steel and blocks oxygen. Furthermore, because Si is the element with the strongest bond to O in alloy compositions, it also reduces the oxygen content in the molten steel. This improves the fluidity of the molten steel and makes steelmaking easier. Si also reduces iron loss and optimizes the soft magnetic properties of the strip. In the present application, the atomic percentage of Si is 3.98 to 9.5%. Specifically, the atomic percentage of Si may be 3.98%, 4.89%, 5.62%, 6.87%, 7.21%, 8.25%, or 9.45%. If the atomic percentage of Si is less than 3.98%, the smoothness of the process will be significantly reduced when producing amorphous strip using the single-roll quenching method. The molten steel surface will be exposed to the atmosphere, causing secondary oxidation, resulting in the formation of oxide slag and reducing the cleanliness of the molten steel. If the atomic percentage of Si is more than 9.5%, the surface tension of the alloy will be excessive, significantly reducing the heat transfer coefficient and increasing the coefficient of variation δQ.

[0033] The relatively low atomic weight of B allows for more B atoms to be present at the same mass fraction, resulting in a larger negative enthalpy of mixing with Fe. Therefore, B primarily enhances the glass-forming ability of alloys. However, excessive B content can degrade the alloy's soft magnetic properties, primarily manifesting as a decrease in saturation magnetic induction and increased loss. Furthermore, the applicant observed through combustion calculations that the B combustion rate can reach 10% at high B content. This is because, at normal melting temperatures, as the B content increases, the activity of B exceeds that of Si, while the Si content remains unchanged, resulting in a large amount of B combining with oxygen to form B2O3. This oxide has a melting point below 500°C and a viscosity much lower than that of SiO2, making it easily trapped in molten steel and difficult to separate from it. When casting in a non-vacuum environment, surface defects (such as scratches on the strip surface, reduced density, and stacking coefficient) often occur in alloy strips. Conversely, if the atomic percentage of B element is low, the glass-forming ability of the high-Fe alloy becomes insufficient, making it difficult to obtain a completely amorphous quenched alloy strip. In this application, the atomic percentage of B element is 9.58 to 12.0%. Specifically, the atomic percentage of B element may be 9.58%, 10.12%, 10.57%, 10.66%, 11.53%, or 11.77%.

[0034] The most significant effect of carbon is to lower the melting point of the alloy system. Based on current knowledge of carbon and high-carbon steels, the melting point of an alloy composition decreases by more than 100°C for every 0.1% increase in the mass percentage of carbon. Therefore, the addition of carbon significantly lowers the melting point of the entire alloy, lowering the eutectic temperature in the Fe-Si phase diagram and thereby enhancing the alloy's glass-forming ability. Furthermore, lowering the alloy's melting point improves the fluidity of the molten steel, allowing for a corresponding reduction in the casting temperature, reducing the cooling capacity requirements of the crystallizer and thermal erosion of the copper rollers, thereby reducing costs. However, more carbon is not necessarily better. Applicant has found that the toughness of an alloy composition decreases when the atomic percentage of carbon exceeds 1.5%. This is because an increase in carbon content reduces the limit for cleavage cracking when the alloy is subjected to external stress, changing the fracture mode from ductile to brittle, and increasing the number of alloy strip fragments during subsequent forming processes. In the present application, the atomic percentage of the C element is 0.1 to 1.3%. Specifically, the atomic percentage of the C element may be 0.12%, 0.45%, 0.54%, 0.86%, 1.19%, 1.24%, or 1.28%.

[0035] In a specific embodiment of the present invention, the iron-based amorphous alloy strip has an Fe atomic percentage content of 82.63%, a Si atomic percentage content of 5.87%, a B atomic percentage content of 10.12%, and a C atomic percentage content of 1.28%. In this case, the strip is produced smoothly, the saturation magnetic induction strength meets the requirement of 1.60 T or more, and the δQ is only 0.5%, indicating excellent cooling uniformity.

[0036] The iron-based amorphous alloy strip provided in the embodiment of the present invention has a specific heat capacity at 100°C of 0.40 to 0.47 J / (g·°C).

[0037] An embodiment of the present invention also provides a method for preparing the iron-based amorphous alloy strip, comprising: a Si b B c C dThe method includes blending raw materials according to the above formula (1), melting the blended raw materials, and single-roller quenching the melted raw materials to obtain an iron-based amorphous alloy strip.

[0038] Furthermore, in the single-roll quenching method, molten steel is dropped onto the surface of a copper roll rotating at high speed. The casting temperature of the molten steel is 1400 to 1465°C, the linear velocity of the copper roll is 19 to 25 m / s, and a cooling water channel is provided inside the copper roll, through which a flow rate of 100 to 300 m 3 / h of cooling water is supplied.

[0039] The iron-based amorphous alloy strip obtained by the above preparation method has a core loss P≦0.2 W / kg and an excitation power Pe≦0.33 VA / kg under the conditions of 1.3 T and 60 Hz after heat treatment.

[0040] The technical effects achieved by the present application are demonstrated by the following specific examples, which are intended to provide a better understanding of the present application and are not intended to limit the present application.

[0041] Experiment 1: The effect of different compositions on Bs (saturation magnetic induction), glass forming ability, and cooling uniformity.

[0042] Raw materials of different compositions were weighed and mixed in predetermined ratios and melted in a medium-frequency induction furnace to obtain molten steel. Then, strips were produced using the single-roll quenching method. In this method, molten steel at a predetermined temperature was introduced through a nozzle slit with a predetermined shape onto the surface of a rapidly rotating crystallizer. The casting temperature of the molten steel was 1420°C. The beryllium copper crystallizer was fed with a flow rate of 180 m 3 / h cooling water was installed inside the crystallizer. The linear velocity of the crystallizer was 20 m / s.

[0043] During the preparation process, the smoothness of the strip preparation was evaluated (if the molten steel was completely quenched into a sufficiently amorphous strip by the single-roll quenching method during the preparation process without any abnormalities, the process was evaluated as smooth strip preparation). The saturation magnetic induction of the obtained strip was measured using a vibration-damped magnetometer.

[0044] Table 1 below shows the results of preparing different compositions.

[0045] [Table 1]

[0046] Completely amorphous quenched strips were obtained from the alloy systems of Examples 1 to 21 using a single-roll quenching method. The amorphousness of the strips produced in Examples 1 to 21 was analyzed by XRD. The results showed that all strips produced by the above method were completely amorphous, with only one broad, diffuse "steamed bun" peak in the 0 to 90° range. The saturation magnetic inductions of the samples were measured using a vibration-damped magnetometer, and all exceeded 1.60 T.

[0047] As can be seen from Table 1, in Comparative Example 1, which had a high atomic percentage of Fe in its composition (86.81%), phenomena such as curling and flame eruptions were observed during production, but these were not observed in the other Examples or Comparative Examples. The surface of the strip in Comparative Example 1 showed obvious oxidative discoloration during production, making it difficult to obtain a complete strip. A sample was taken and its internal structure was examined using XRD. The XRD analysis revealed a diffraction peak at a 45° angle, indicating that crystallization had occurred in this composition, making it impossible to obtain a completely amorphous quenched strip.

[0048] In Comparative Example 2, a completely amorphous quenched strip was obtained, but due to the low Fe content, the saturation magnetic induction strength was only 1.57 T, making it difficult to meet the current high Bs requirement. Therefore, to achieve a saturation magnetic induction of 1.60 T or more, the atomic percentage of the Fe element content in the alloy composition system must be 80.4% or more. In Example 6, where the Fe content is 81.3%, the Bs of the resulting strip was 1.62 T, indicating that the Fe content should preferably be in the range of 81.3% to 83.50%.

[0049] In the alloy of Comparative Example 1, the atomic percentage of B was only 6.49%, resulting in insufficient glass-forming ability of the alloy composition and increased cooling strength requirements. The applicant discovered that to produce a completely amorphous quenched strip, the B content in the alloy composition should be 9.0% or more. When the B content in the alloy composition increases, for example, when the B content reaches 15.3% in Comparative Example 4, the smoothness of the strip significantly decreases, resulting in defects such as scratches and slag lines on the strip surface during the production process. This often results in a decrease in the stacking coefficient of the strip, reduced fluidity of the molten steel, and difficulty in drawing. Therefore, the B content should be limited to 14.0% or less.

[0050] The composition of Comparative Example 3 resulted in strips with high brittleness and poor smoothness during the manufacturing process. Although the saturation magnetic induction strength met the requirement of 1.60 T or more, the high brittleness prevented it from meeting the industrial mass production requirements for subsequent use. Therefore, the C content must be less than 1.5%.

[0051] As mentioned above, alloy strips with high saturation induction and high glass-forming ability were produced, but some compositions still exhibited non-uniform cooling phenomena.

[0052] Differences in cooling intensity across the weld pool lead to differences in the heat release rate at the first crystallization peak of the strip. The cooling difference across the weld pool represents differences in heat exchange. Theoretically, heat exchange is related to the heat capacity, density, and heat transfer coefficient of the molten steel with the copper roller. Because the specific heat capacity of a substance depends on temperature, the specific heat capacity of molten steel with different compositions can be calculated by measuring the heat absorbed or released per unit mass of strip with different compositions per 1°C increase or decrease. Similarly, because it is difficult to measure the density of molten steel in the weld pool, the density of the prepared strip can be used instead.

[0053] To further explore the appropriate composition range, the applicant selected several composition examples from the above examples, prepared corresponding strips using the single-roller quenching method, and measured the specific heat capacity (c) of the strips with different compositions at 100°C and the density of the strips with different compositions at room temperature. Furthermore, DSC tests were performed on strip samples of the same mass and size taken from the area where the width of the strip edge occupies 10% of the strip width and the area where the width of the strip center occupies 10% of the strip width. The heat release rate of the strip sample within 10% of the strip edge is defined as Qa, and the heat release rate of the strip sample within 10% of the center is defined as Qb. The coefficient of variation for different compositions was calculated as δQ = (Qa - Qb) / Qa * 100%. Table 2 below shows the δQ values ​​obtained for different compositions in the experiment.

[0054] [Table 2]

[0055] The data in Table 2 show that in all of Examples 15 to 21, strips were produced with a coefficient of variation ΔQ of less than 4%. This means that the strips exhibited good cooling uniformity across the width, with Example 18 in particular exhibiting a very low coefficient of variation of 0.5%. This low coefficient of variation indicates good cooling uniformity across the width of the strips during the production process, and strips with such excellent uniformity maintain good appearance and magnetic properties even during subsequent processing and heat treatment.

[0056] Increasing the Fe content in the alloy composition increases the density of the strip, but the specific heat capacity of the alloy decreases accordingly. Furthermore, Si not only affects the specific heat capacity of the alloy, but also influences the surface tension of the alloy, which in turn affects the heat transfer coefficient between the molten steel and the crystallizer surface. For example, in Comparative Example 8, when the Si content exceeded 9.5%, the surface tension of the alloy became excessive, significantly reducing the heat transfer coefficient and increasing the coefficient of variation ΔQ. Therefore, the atomic percentage of Si is optimized to be between 3.98% and 9.5%, more preferably between 5.62% and 9.5%. For example, in Example 18, an extremely low coefficient of variation ΔQ was achieved in the final strip.

[0057] Comparing Example 17 with Comparative Example 7, it can be seen that when the B content is less than 9.58%, the coefficient of variation ΔQ exceeds 4%. On the other hand, comparing Examples 19 and 21 with Comparative Example 5, it can be seen that when the atomic percentage of B exceeds 12%, a strip with stable cooling strength cannot be obtained. Therefore, the atomic percentage of B is optimized to be 9.58% to 12.0%.

[0058] Comparing Example 20 with Comparative Example 9, it can be seen that when the carbon content in the alloy exceeds 1.30%, the difference in heat generation between the end and center of the strip becomes significant. Therefore, the atomic percentage of carbon is optimized to be 0.1% to 1.3%.

[0059] Experiment 2: Effect of cooling process on strip performance In Experiment 1, strips with a saturation magnetic induction of over 1.60 T, strong glass-forming ability, and uniform cooling strength were produced. However, during the subsequent preparation of transformer cores, variations in the performance of the strips were observed depending on the cooling process. Therefore, the applicant conducted further research into the cooling process in the single-roll quenching method.

[0060] Example 18 used the alloy composition of the following examples. Raw materials were weighed and melted in a medium-frequency induction furnace to obtain molten steel, which was then processed into strips by single-roll quenching. Experiments were conducted with the single-roll quenching method, varying the casting temperature, linear velocity, and circulating water flow rate. The strips were wound around toroidal cores, heat-treated, and then the core loss and excitation power were measured using a silicon steel testing machine under conditions of 60 Hz and 1.3 T.

[0061] Table 3 below shows the soft magnetic properties for different cooling processes.

[0062] [Table 3]

[0063] These results demonstrate that amorphous strip with excellent soft magnetic properties can be produced by adjusting the cooling process, including the casting temperature, crystallizer linear velocity, and water flow rate. After heat treatment, the strip exhibited a core loss P of 0.2 W / kg or less and an excitation power Pe of 0.33 VA / kg or less under conditions of 1.3 T and 60 Hz. As shown in Examples 22 to 28, the amorphous strip produced in Example 23 achieved optimal performance after heat treatment. The casting temperature directly affects the heat exchange between the crystallizer surface and the molten steel in the molten pool. To ensure that the fluidity of the molten steel meets the casting requirements, the casting temperature must be higher than the melting point and maintain a certain degree of superheat. When the casting temperature was too high, as in Comparative Example 10, the casting temperature of the molten steel reached 1470°C, and both the core loss and excitation power of the strip increased, indicating insufficient cooling capacity, despite the corresponding increases in linear velocity and water flow rate.

[0064] Similarly, the crystallizer's linear velocity has a decisive impact on the crystallizer's cooling capacity. A low crystallizer linear velocity results in a large amount of molten steel drawn per crystallizer surface area, resulting in insufficient energy, resulting in a reduced crystallizer's cooling capacity. The applicant has found that in the production of amorphous alloys using high-Bs alloy systems, maintaining a crystallizer linear velocity of 19 m / s or higher is necessary to produce a completely amorphous quenched strip. However, a higher crystallizer cooling intensity is not necessarily better. For example, in Comparative Example 12, when the crystallizer linear velocity was as high as 29 m / s, the strip core loss met the requirements, but the pumping power was high. This is because excessive cooling intensity solidifies a large amount of quenching stress during cooling. During heat treatment, sufficient insulation is necessary to remove residual internal quenching stress, but it is unclear whether long-term insulation adversely affects the strip's core loss. Therefore, a crystallizer linear velocity in the range of 19 to 25 m / s is preferred.

[0065] The water flow rate of the crystallizer has the same effect as the linear velocity on the cooling capacity of the crystallizer. The cooling capacity of the crystallizer is not necessarily better the stronger it is. Excessive water flow rate creates residual quenching stresses, which increases the excitation power of the strip in back-end applications. As shown in Comparative Example 14, strips processed into transformer cores are prone to problems such as excessive noise. On the other hand, as shown in Comparative Example 13, when the water flow rate of the crystallizer is 82 m / s, the cooling capacity of the crystallizer is not as high as the linear velocity. 3 / h, both the core loss and pump power of the heat-treated strip increased, indicating that the cooling capacity of the crystallizer was insufficient. 3 / h range is preferred.

[0066] In summary, the present invention produces amorphous alloy strip with high saturation magnetic induction, high glass-forming ability, uniform cooling strength and excellent performance, solves the problem of non-uniform cooling of alloy systems with high Bs (≧1.60 T), and achieves the technical effects described in the present invention.

[0067] Finally, it should be noted that the above embodiments are only used to describe the technical solutions of the present application, and do not limit the present application. Although the present application has been described in detail with reference to the above embodiments, those skilled in the art should understand that the technical solutions described in the above embodiments can still be modified or some of its technical features can be replaced with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

Claims

1. Fe ａ Si ｂ B ｃ C ｄ It has a chemical composition of a, b, c, and d represent the atomic percentages of the corresponding components, respectively, and are 80.4%≦a≦83.5%, 3.98%≦b≦9.5%, 9.58%≦c≦12.0%, 0.1%≦d≦1.3%, and 99.9%≦a+b+c+d≦100%, and the remainder is unavoidable impurities. Iron-based amorphous alloy strip.

2. The iron-based amorphous alloy strip has a saturation magnetic induction strength of 1.6 T or more. The iron-based amorphous alloy strip according to claim 1.

3. Fe is present in an atomic percentage of 81.3%≦a≦83.5%; The iron-based amorphous alloy strip according to claim 1.

4. Si is present in an atomic percentage of 5.62%≦b≦9.5%; The iron-based amorphous alloy strip according to claim 1.

5. Fe is present in an atomic percentage of 82.63%, Si is present in an atomic percentage of 5.62%, B is present in an atomic percentage of 10.37%, and C is present in an atomic percentage of 1.28%; The iron-based amorphous alloy strip according to claim 1.

6. The specific heat capacity at 100°C is 0.40 to 0.47 J / (g °C), An iron-based amorphous alloy strip according to any one of claims 1 to 5.

7. the iron-based amorphous alloy strip is divided into n equal zones along its width, an end zone occupying 10% of the strip width is designated as zone a, and a central zone occupying 10% of the strip width is designated as zone b, samples are taken within the ranges of zone a and b, and their first crystallization peak areas are detected using a differential scanning calorimeter to obtain calorific values ​​Qa and Qb, and the coefficient of variation δQ=(Qa-Qb) / Qa*100% of the iron-based amorphous alloy strip is 4% or less; An iron-based amorphous alloy strip according to any one of claims 1 to 5.

8. A method for preparing the iron-based amorphous alloy strip according to any one of claims 1 to 7, comprising the steps of: ａ Si ｂ B ｃ C ｄ and melting the blended raw materials and quenching them with a single roller to obtain the iron-based amorphous alloy strip.

9. In the single roll quenching process, the casting temperature of the molten steel is 1400 to 1465°C, the linear speed of the copper roll is 19 to 25 m / s, a cooling water channel is provided inside the copper roll, and 100 to 300 m of cooling water is passed through the cooling water channel. ３ Cooling water is supplied at a flow rate of 1 / h. A method for preparing the iron-based amorphous alloy strip according to claim 8.

10. After the heat treatment, the iron-based amorphous alloy strip has a core loss P≦0.2 W / kg and an excitation power Pe≦0.33 VA / kg under the conditions of 1.3 T and 60 Hz.

10. A method for preparing the iron-based amorphous alloy strip according to claim 9.

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