Non-oriented electrical steel sheet having good magnetic properties and its manufacturing method

Abstract

In the present invention, a non-oriented electrical steel sheet having good magnetic properties is disclosed. The non-oriented electrical steel sheet contains Fe and inevitable impurities, and further contains the following chemical elements by mass percentage: 0 < C ≤ 0.0015%, Si: 0.2 - 1.8%, Mn: 0.2 - 0.4%, Al: 0.2 - 0.6%, V: 0.002 - 0.005%, and N < 0.002%. Further, in the present invention, a manufacturing method for the non-oriented electrical steel sheet having good magnetic properties is disclosed. The manufacturing method includes the following steps: (1) a step of smelting and casting; (2) a step of hot rolling, wherein the steel coil obtained after hot rolling is not subjected to full annealing or coated annealing and directly enters the next step; (3) a step of pickling; (4) a step of cold rolling; and (5) a step of continuous annealing, wherein the steel sheet is rapidly heated to a target soaking temperature at a heating rate of 50 - 5000 °C / s after cold rolling.

Description

[Technical field]

[0001] Technical Field The present invention relates to a steel sheet and a manufacturing method thereof, and in particular to a non-oriented electrical steel sheet and a manufacturing method thereof. [Background technology]

[0002] background In the prior art, non-oriented electrical steel sheets are commonly used to manufacture stators and rotors of iron cores for use in motors, generators, compressors, and high speed motors, drive motors and other products.

[0003] However, in recent years, with increasing demands for high efficiency, energy saving and consumption reduction in the user market, the existing non-oriented electrical steel sheets gradually fail to meet the market demands; therefore, in order to meet the new technical demands of the market for non-oriented electrical steel sheets, it is urgent to develop non-oriented electrical steel sheets with higher magnetic induction and lower core loss.

[0004] In order to achieve the best possible electromagnetic performance for non-oriented electrical steel sheets, some researchers have conducted a lot of research and achieved certain research results, but the practical application results are not very satisfactory.

[0005] For example, Chinese patent application publication CN103014503A, entitled "Acid-corrosion-resistant non-oriented silicon steel with high magnetic induction and low core loss without normalizing and its manufacturing method", published on April 3, 2013, points out that by adding 0.20%-0.45% Sn+Cu to the steel, the structure of the final strip steel can be improved due to grain boundary segregation, so that good magnetic induction performance can be obtained. However, since Sn and Cu are precious metals, it significantly increases the manufacturing cost of the steel, and Cu tends to cause related quality defects on the surface of the strip steel. Therefore, in the practical application process, the technical solution of this patent application has strict requirements on the manufacturing process, and the resulting product has a relatively low cost performance.

[0006] As another example, Japanese Patent Application Publication No. 10-183227 and Japanese Patent Application Publication No. 2004-169141 point out that by strong deoxidation and desulfurization of molten steel by adding appropriate amount of rare earth elements and calcium alloys to steel, inclusions in steel can be removed and cleanliness of steel can be improved, so that the electromagnetic performance of final strip steel can be improved efficiently and favorably. In addition, the above Japanese patent documents also point out that by reducing harmful elements C, S, O, N, Nb, V and Ti in steel and at the same time combining high tapping temperature, high final rolling temperature and high coil winding temperature in hot rolling process, hot rolled steel sheet with coarse grains can be obtained, which is beneficial to the roughening of inclusions and thus plays a good role in promoting the improvement of magnetic performance of final strip steel. However, the disadvantages of such a technical solution are the high energy consumption of hot rolling and the poor stability of the finish rolling process due to the significant increase of the preheating temperature and the shift of the phase transition point, and the high coiling temperature easily causes red scale defects.

[0007] In view of the above, the present inventors have designed and intended to obtain a novel non-oriented electrical steel sheet with good magnetic performance, which aims to improve the electromagnetic performance of the electrical steel, reduce the iron loss and improve the magnetic induction.

Summary of the Invention

Means for Solving the Problems

[0008] Gist of the Invention One of the objects of the present invention is to provide a non-oriented electromagnetic steel sheet having good magnetic properties, which aims to improve the electromagnetic properties of the non-oriented electromagnetic steel sheet, reduce iron loss, and improve magnetic induction.

[0009] To achieve the above object, the present invention provides a non-oriented electromagnetic steel sheet having good magnetic properties, which contains Fe and inevitable impurities, and the following chemical elements by mass percentage: 0 < C ≦ 0.0015%, Si: 0.2 - 1.8%, Mn: 0.2 - 0.4%, Al: 0.2 - 0.6%, V: 0.002 - 0.005%, and N < 0.002% further includes.

[0010] Preferably, the non-oriented electromagnetic steel sheet according to the present invention has the following chemical elements by mass percentage: 0 < C ≦ 0.0015%, Si: 0.2 - 1.8%, Mn: 0.2 - 0.4%, Al: 0.2 - 0.6%, V: 0.002 - 0.005%, and N < 0.002%; and the balance is Fe and inevitable impurities includes.

[0011] The chemical elements for the non-oriented electromagnetic steel sheet according to the present invention are designed based on the following principles.

[0012] C: In the non-oriented electromagnetic steel sheet according to the present invention, the content of C in the steel should not be too high. When the content of C in the steel for the steel sheet of the present invention is higher than 0.0015%, C preferentially combines with Nb and Ti to form inclusions having fine dimensions, which causes an increase in iron loss. In view of this, in order to fully exert the beneficial effects of C, in the non-oriented electromagnetic steel sheet according to the present invention, the mass percentage content of C is controlled to be 0 < C ≦ 0.0015%.

[0013] Si: In the present invention, Si is added to the non-oriented electrical steel sheet with a medium to low content. If the content of Si is higher than 1.8%, it not only increases the manufacturing cost of the steel sheet, but also significantly deteriorates the magnetic induction of the steel; if the content of Si is lower than 0.2%, it cannot achieve the effect of effectively reducing iron loss. In view of this, in the non-oriented electrical steel sheet according to the present invention, the mass percent content of Si is controlled to be between 0.2% and 1.8%.

[0014] Mn: In the non-oriented electrical steel sheet according to the present invention, an appropriate amount of Mn is added together with S to form MnS, which is beneficial to control the morphology and number of inclusions and can effectively reduce the harm to magnetic performance, so it is necessary to add more than 0.2% Mn; on the other hand, if the content of added Mn is higher than 0.4%, the recrystallized structure will deteriorate and the magnetic induction of the steel sheet will decrease. In view of the above, and taking into account the beneficial and adverse effects of Mn, in the non-oriented electrical steel sheet according to the present invention, the mass percent content of Mn is 0.2-0.4%.

[0015] Al: In the non-oriented electrical steel sheet according to the present invention, if the content of Al added to the steel for the steel sheet according to the present invention is higher than 0.6%, the performance of the steel sheet will be significantly deteriorated; on the other hand, if the content of Al added to the steel sheet is lower than 0.2%, it cannot achieve a good effect of reducing iron loss. In view of this, in the non-oriented electrical steel sheet according to the present invention, the mass percent content of Al is controlled to be between 0.2% and 0.6%.

[0016] V: In the prior art, V is usually regarded as a harmful element in non-oriented electrical steel sheets, and the lower the V content, the better. However, in the non-oriented electrical steel sheets according to the present invention, V is used as an important beneficial element. Unlike the prior art, which reduces the V content as much as possible to reduce the content of harmful inclusions as much as possible, in the present invention, an appropriate amount of V is intentionally added, and in combination with the adjustment of the manufacturing process and the control of the type and number of N-containing inclusions, the harmless processing of Nb, V and Ti is maximized. In this way, the compatibility and combination of the chemical components beneficial to obtain good magnetic performance and the reasonable prerequisites for controlling the type of inclusions is realized.

[0017] In the technical solution according to the present invention, if the content of V in the steel is lower than 0.002%, the good effect of fixing C and N cannot be achieved, and the V inclusions are diverse and small in size; on the other hand, if the content of V in the steel is too high and exceeds 0.005%, the number of inclusions formed by V together with C and N increases greatly, which strongly hinders grain growth and deteriorates the magnetic performance of the steel. Therefore, in order to exert the beneficial effect of V, the mass percent content of V is controlled to be between 0.002% and 0.005% in the non-oriented electrical steel sheet according to the present invention.

[0018] N: In the non-oriented electrical steel sheet according to the present invention, as a harmful impurity element, the content of N should not be too high. If the content of N in the steel exceeds 0.002%, the number of inclusions formed by N together with Nb, V, Ti, Al and other elements will increase greatly, which strongly hinders grain growth and deteriorates the magnetic performance of the steel. In view of this, in the non-oriented electrical steel sheet according to the present invention, the mass percent content of N is controlled to satisfy: N<0.002%.

[0019] Preferably, in the non-oriented electrical steel sheet according to the present invention, among the unavoidable impurities, Nb≦0.002% and Ti≦0.002%.

[0020] In the above technical solution of the present invention, both Nb and Ti are inevitable impurity elements in steel, and the contents of impurity elements in steel should be controlled as low as possible if technical conditions permit.

[0021] Nb: In the non-oriented electrical steel sheet according to the present invention, if the Nb content is higher than 0.002%, the NbN inclusions in the steel will increase abnormally, which will cause a sharp increase in the iron loss of the finished steel sheet. Therefore, in the present invention, the impurity element Nb must be strictly controlled to satisfy: Nb≦0.002%.

[0022] Ti: In the non-oriented electrical steel sheet according to the present invention, if the Ti content is higher than 0.002%, the TiN inclusions in the steel will increase abnormally, which will cause a sharp increase in iron loss of the finished steel sheet. Therefore, in the present invention, the impurity element Ti needs to be strictly controlled to satisfy: Ti≦0.002%.

[0023] Preferably, the non-oriented electrical steel sheet according to the present invention contains N-containing inclusions as the major inclusions, and the N-containing inclusions include individual VN and AlN and / or composite VN, AlN, NbN and TiN.

[0024] In contrast to "composite," the term "individual" refers to the state in which the different inclusions are not doped with each other.

[0025] Preferably, in the non-oriented electrical steel sheet according to the present invention, the N-containing inclusions have a size of 200-500 nm.

[0026] Preferably, in the non-oriented electrical steel sheet according to the present invention, the volume fraction ratio of VN to N-containing inclusions is ≧0.85.

[0027] In the present invention, the content of the beneficial element V is controlled to be between 0.002% and 0.005% in order to form VN inclusions having a relatively large size as much as possible instead of fine NbN and TiN inclusions. In order to avoid the formation of C-containing inclusions such as fine NbN, TiN, Nb, V, Ti, etc., in the present invention, the content of C is strictly limited to 0 < C ≤ 0.0015%, and in the actual production process, from the perspective of manufacturing difficulty, the content of C can be more preferably controlled to 0 < C ≤ 0.0010%. Under the conditions of the above chemical elements and when the content of Al in the steel is 0.2 - 0.6%, N-containing inclusions become the main factor limiting the magnetic performance of the finished steel sheet.

[0028] Therefore, in the present invention, it is preferably limited so that the volume fraction ratio of VN to N-containing inclusions in the steel is ≥ 0.85, and it is necessary to reduce the generation of non-VN type inclusions. The main principle of the adjustment in this specification is to adjust the content of V in the steel, thereby adjusting the proportion of VN inclusions in all N-containing inclusions in the steel. Furthermore, due to the high content of Al in the steel, which is between 0.2% and 0.6%, a large number of AlN inclusions can be formed in the steel. After collision, combination and floating, AlN inclusions having a relatively small size can remain in the steel and can combine with VN inclusions, thus increasing the size of the composite inclusions and reducing the harm caused by them.

[0029] Therefore, when the number of VN inclusions formed in the steel is too small, the composite effect with AlN inclusions cannot be achieved. In this case, the AlN inclusions are small in size and cannot be removed by floating and remain in the steel; when the number of VN inclusions is too large, in addition to the composite with AlN inclusions, individual AlN remains in the steel, and the harm caused by VN inclusions increases with the increase in the number of VN inclusions.

[0030] Preferably, in the non-oriented electrical steel sheet according to the present invention, the iron loss P 15 / 50 is ≤ 4.2 W / kg, and the magnetic induction B 50 is ≥ 1.73 T.

[0031] Therefore, another object of the present invention is to provide a manufacturing method for the above-mentioned non-oriented electrical steel sheet with good magnetic properties, which is simple and feasible, by which a non-oriented electrical steel sheet with good magnetic properties can be obtained, in which the steel sheet has an iron loss P≦4.2W / kg. 15 / 50 and magnetic induction B ≥ 1.73T 50 has.

[0032] In order to achieve the above object, the present invention provides a manufacturing method for a non-oriented electrical steel sheet with good magnetic performance, which includes the following steps: (1) Smelting and casting processes; (2) hot rolling, in which the steel coil obtained after hot rolling is directly introduced into the next process without being subjected to normalizing annealing or cover annealing; (3) pickling to obtain a pickled steel sheet; (4) cold rolling to obtain a cold rolled steel sheet; and (5) Continuous annealing, in which the cold rolled steel sheet is rapidly heated to the target soak temperature at a heating rate of 50-5000°C / s.

[0033] In the present invention, we optimize the design of the chemical composition of steel and define a reasonable manufacturing process. The continuous casting slab obtained after smelting and casting does not need normalizing annealing or coating annealing after being hot rolled; the slab can be continuously annealed in an electromagnetic induction device with rapid heating function after being directly subjected to pickling and cold rolling, so that the electromagnetic performance required by the design of the present invention can be obtained. In the present invention, there is no special requirement for hot rolling, pickling and cold rolling, on the principle of not increasing the production cost and technical difficulty of steel.

[0034] In the prior art, there are some technical solutions that do not require normalizing annealing or coating annealing, but the steels prepared by these technical solutions are mostly high silicon steels, and the content of Si in these steels is high; it should be noted that unlike the above prior art, the Si in the steel of the present invention is only 0.2-1.8%, which is a medium to low silicon steel, and normalizing annealing or coating annealing is not required when medium to low silicon steel is used.

[0035] In the steelmaking process of the present invention, strict control is required when designing the chemical composition of the steel, and the content of V in the steel should be particularly controlled. After smelting and casting, a steel ingot can be obtained; after hot rolling, the steel ingot does not need normalizing annealing or coating annealing, and after pickling and descaling treatment, the pickled steel plate can be cold rolled to the target cold rolling thickness at one time, and then continuously annealed in an electromagnetic induction device with rapid heating function, and the annealing atmosphere can be controlled to be a mixed gas of H2 and N2.

[0036] In step (5) of the above manufacturing method according to the present invention, the electromagnetic induction device with rapid heating function is not limited to vertical or horizontal magnetism, but its heating capacity should meet the requirement of rapidly heating the cold rolled steel sheet to the target soaking temperature during continuous annealing. The target soaking temperature can usually be 500-1100°C, and the starting temperature of heating can be a temperature lower than the soaking temperature, such as room temperature. The heating rate of the cold rolled steel sheet in the present invention is controlled to be 50-5000°C / s, which is much higher than the heating rate of the conventional continuous annealing equipment by 1-30°C / s. However, in some embodiments, the heating rate can be controlled to be 80-550°C / s according to the production and actual quality requirements of the finished steel sheet.

[0037] Compared with the traditional annealing method using gas and / or electric heating, low heating rate (usually lower than 30℃ / s), the present invention adopts an electromagnetic induction device with rapid heating function for continuous annealing, thereby realizing rapid heating to the specified target soaking temperature of the cold rolled steel sheet in a short time. The purpose of using rapid heating is to effectively inhibit the recovery of the cold rolled steel sheet during continuous annealing, so that the residual deformation energy storage of the cold rolled steel sheet can be significantly increased before recrystallization, which can result in the accumulation and increase of the driving force for nucleation, and can promote the nucleation and migration of high angle grain boundaries. At the same time, the preferred orientation of the crystal nuclei is also reduced, and finally <111> / / ND recrystallized structure components may have a reduced strength. Therefore, the continuous annealing method allows the steel to obtain higher magnetic induction and lower core loss.

[0038] It should be noted that during the rapid heating and continuous annealing of cold rolled steel sheet, in order to further increase the driving force for nucleation and growth, improve and control the final recrystallization effect, and ensure a low proportion of coarse grain structure and harmful grain orientation after continuous annealing, it is also necessary to properly limit the heating rate of rapid heating annealing to be between 50 ° C / s and 5000 ° C / s. If the heating rate of rapid heating is too low, and the heating rate is lower than 50 ° C / s, the release of energy storage of cold rolling deformation is too fast, which is not conducive to the subsequent favorable structure control; if the rapid heating rate is too fast, and the heating rate is higher than 5000 ° C / s, the requirements on equipment capacity are too high, and the cost is expensive, which causes the cold rolled strip to stay in the high temperature stage for too long and poor grain structure uniformity.

[0039] Preferably, in the manufacturing method according to the present invention, in step (5), the target soaking temperature is 500-1100°C.

[0040] Preferably, in the manufacturing method according to the present invention, in step (5), the cold rolled steel sheet is rapidly heated to the target soak temperature at a heating rate of 80-550° C. / s.

[0041] Preferably, in the manufacturing method according to the present invention, in step (2), the residence time of the cast slab in the furnace during hot rolling is controlled to be 120-360 minutes, the initial rolling temperature is controlled to be 1000-1250°C, the final rolling temperature is controlled to be 650-1000°C, and the coiling temperature is controlled to be 550-950°C.

[0042] Preferably, in the manufacturing method according to the present invention, in step (2), the target thickness of the hot-rolled steel sheet is controlled to be 0.8-3.5 mm; in step (4), the pickled steel sheet is cold-rolled to the target cold-rolling thickness in one go.

[0043] Compared with the prior art, the non-oriented electrical steel sheet with good magnetic performance and its manufacturing method according to the present invention have the following advantages and beneficial effects: Different from the prior art, in the steelmaking process of the present invention, V is employed as a beneficial element, and the content of V is intentionally controlled.

[0044] In the non-oriented electrical steel sheet according to the present invention, the inventors optimize the chemical element composition ratio, so that the continuous cast slab obtained after smelting and casting does not need normalizing annealing or coating annealing, and can be directly pickled and cold rolled and then rapidly heated, ensuring that the cold rolled steel sheet is rapidly heated to the target soaking temperature at a relatively high heating rate, so as to obtain the electromagnetic performance requirements designed in the present invention.

[0045] The idea of ​​chemical element design of the present invention is completely different from the prior art, and the manufacturing method is simple and feasible; and the non-oriented electrical steel sheet thus manufactured has the characteristics of high magnetic induction and low core loss, and the core loss P 15 / 50 is ≦4.2W / kg, and the magnetic induction B 50 is ≧1.73T. [Brief description of the drawings]

[0046] [Figure 1]FIG. 1 shows diagrammatically the relationship between the volume fraction ratio of vanadium nitride (VN) to N-containing inclusions in the steel in a non-oriented electrical steel sheet according to the invention and the core loss P15 / 50 of the finished steel sheet. [Diagram 2] FIG. 2 shows a schematic diagram of the relationship between the heating rate of rapid heating in a non-oriented electrical steel sheet according to the present invention and the magnetic induction B50 of the finished steel sheet. [Diagram 3] FIG. 3 is a photograph of the microstructure of the finished non-oriented electrical steel sheet of Example 3. [Figure 4] FIG. 4 is a photograph of the microstructure of the comparative steel of Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] Detailed Description The non-oriented electrical steel sheet having good magnetic performance and its manufacturing method according to the present invention will be further described and illustrated with reference to the accompanying drawings and specific examples. However, the description and illustration should not be construed as constituting an excessive limitation on the technical solution of the present invention.

[0048] Examples 1-6 and Comparative Examples 1-3 Table 1 shows the mass percentages of the chemical elements of the non-oriented electrical steel sheets of Examples 1-6 and the comparative steel sheets of Comparative Examples 1-3.

[0049] [Table 1]

[0050] The non-oriented electrical steel sheets of Examples 1-6 and the comparative steel sheets of Comparative Examples 1-3 were all prepared by the following process: (1) A process for smelting and casting steel material having the chemical composition shown in Table 1, in which in the steelmaking process, decarburization is given priority to achieve the designed target, then deoxidation and alloying are carried out, and the V content is adjusted to the target range according to the C, N, Nb and Ti contents in the steel to obtain a molten steel that satisfies the chemical composition design requirements, and then the molten steel is cast into a steel ingot having a specified size.

[0051] (2) hot rolling process, wherein the time of the slab obtained by casting the ingot during hot rolling is controlled to 120-360 minutes, the initial rolling temperature is controlled to 1000-1250°C, the final rolling is controlled to 650-1000°C, the coiling temperature is controlled to 550-950°C, and the hot rolling is carried out for 2-8 passes, and the target thickness of the hot rolled steel plate is controlled to 0.8-3.5 mm, and wherein the steel coil obtained after hot rolling is not subjected to normalizing annealing or coating annealing, but is directly introduced into the next process.

[0052] (3) A process of pickling to obtain pickled steel sheet.

[0053] (4) cold rolling the pickled steel sheet, in which the pickled steel sheet is subjected to cold rolling to a target cold rolled thickness of 0.50 mm in one go.

[0054] (5) A process of continuous annealing, in which the cold-rolled steel sheet is rapidly heated from room temperature to a target soaking temperature of 500-1100°C at a heating rate of 50-5000°C / s by a continuous annealing apparatus having an electromagnetic induction rapid heating device, and soaked for a certain period of time, for example, 10-120 s; and in which the heating rate can be more preferably controlled to be between 80°C / s and 550°C / s; during annealing, the annealing atmosphere can be controlled to be a mixed gas of H2 and N2.

[0055] It should be noted that in the present invention, the chemical compositions and related process parameters in Examples 1-6 all meet the control requirements of the design specifications of the present invention, but in Comparative Examples 1-3, at least one chemical composition or process parameter does not meet the design requirements of the present invention.

[0056] The specific process parameters for the non-oriented electrical steel sheets of Examples 1-6 and the comparative steel sheets of Comparative Examples 1-3 in the above manufacturing process are shown in Table 2.

[0057] [Table 2]

[0058] Samples of the finished products of the non-oriented electrical steel sheets of Examples 1-6 and the comparative steel sheets of Comparative Examples 1-3 were taken respectively and observed and analyzed. It was found that inclusions existed in the steels of the examples and the comparative examples, and the main inclusions were N-containing inclusions. Through further analysis and testing, the average size and specific composition of the N-containing inclusions in the steels of the examples and the comparative examples were obtained, and the relevant observation and analysis results are listed in Table 3 below.

[0059] [Table 3]

[0060] After the above observation and analysis of the inclusions was completed, samples of the non-oriented electrical steel sheets of Examples 1-6 and the comparative steel sheets of Comparative Examples 1-3 were taken again, and the magnetic induction B 50 and iron loss P 15 / 50 were tested and the test results are set forth in Table 4 below.

[0061] The relevant performance test procedures are as follows:

[0062] Magnetic Induction B 50 Test: According to the national standard GB / T 3655-2008, the iron loss performance test was carried out by the Epstein frame method. The test temperature was a constant temperature of 20°C, the sample size was 30 mm x 300 mm, and the target mass was 0.5 kg. The magnetic induction B of the steel sheets of the examples and comparative examples 50 was obtained by this test.

[0063] Iron loss P 15 / 50Test: According to the national standard GB / T 3655-2008, the iron loss performance test was carried out by the Epstein frame method. The test temperature was a constant temperature of 20°C, and the sample size was 30 mm x 300 mm, and the target mass was 0.5 kg. Iron loss P 15 / 50 was obtained by this test.

[0064] Magnetic induction B of the non-oriented electrical steel sheets of Examples 1-6 and the comparative steel sheets of Comparative Example 1-3 50 and iron loss P 15 / 50 The test results are shown in Table 4.

[0065] [Table 4]

[0066] As shown in Table 4 above, in the present invention, the non-oriented electrical steel sheets of Examples 1-6 have a magnetic induction B in the range of 1.74-1.80 T. 50 and core losses P in the range of 3.2-4.2 W / kg 15 / 50 All of these are obviously superior to those of the comparative steel plates of Comparative Examples 1-3. Comparative Examples 1-3 do not satisfy the conditions specified in the technical solution of the present invention, so the technical effects produced thereby are inferior to those of the present invention.

[0067] FIG. 1 shows the relationship between the volume fraction ratio of VN to N-containing inclusions in the non-oriented electrical steel sheet according to the present invention and the iron loss P 15 / 50 The relationship between is shown diagrammatically.

[0068] As shown in Figure 1, the iron loss P of the finished steel plate increases with increasing volume fraction ratio of VN to N-containing inclusions in the steel during both conventional heating and rapid heating. 15 / 50 However, the iron loss P of the finished steel plate that has been rapidly heated 15 / 50 decreases remarkably fast, and when the volume fraction ratio of VN to N-containing inclusions in the steel reaches 85% or more, the iron loss P of the rapidly heated finished steel plate 15 / 50can be lower than 4.2 W / kg, satisfying the design requirements of the present invention.

[0069] FIG. 2 shows the heating rate of the rapid heating of the non-oriented electrical steel sheet according to the present invention and the magnetic induction B of the finished steel sheet. 50 The relationship between is shown diagrammatically.

[0070] As shown in FIG. 2, when the heating rate of rapid heating in non-oriented electrical steel sheet increases, the magnetic induction of the finished non-oriented electrical steel sheet increases gradually and remains stable within the range of 50-5000°C / s, which meets the control requirements of the present invention whose designed lower limit is 1.73T; and after exceeding 5000°C / s, the magnetic induction of the finished non-oriented electrical steel sheet rapidly deteriorates and becomes lower than the control lower limit of 1.73T, which does not meet the control requirements for magnetic induction designed in the present invention.

[0071] FIG. 3 is a photograph of the microstructure of the finished non-oriented electrical steel sheet of Example 3.

[0072] As shown in FIG. 3, in the embodiment of Example 3, the microstructure of the non-oriented electrical steel sheet is fully recrystallized, and the recrystallized grains are all relatively uniform equiaxed grains with coarse and developed grain sizes.

[0073] FIG. 4 is a photograph of the microstructure of the comparative steel of Comparative Example 2.

[0074] As shown in Figure 4, in the embodiment of Comparative Example 2, the microstructure of the comparative steel is fully recrystallized, but the proportion of equiaxed grains in the recrystallized grains is low, the size is fine, and the grain size distribution is relatively dispersed. The grains with larger grain sizes are abnormally grown "island grains".

[0075] It should be noted that the combinations of the various features of the present invention are not limited to those described in the claims or embodiments, and all features of the present invention can be freely combined and combined in any manner, as long as they are not mutually inconsistent.

[0076] It should also be noted that the above examples are merely specific embodiments of the present invention, and the present invention is not limited to the above examples, and it is obvious that those skilled in the art can make similar modifications and changes based on the disclosure of the present invention, and easily replace them, all of which are within the scope of the claims.

Claims

1. Contains Fe and inevitable impurities and contains the following chemical elements in mass percent: 0<C≦0.0015%, Si: 0.2-1.8%, Mn: 0.2-0.4%, Al: 0.2-0.6%, V: 0.002-0.005%, and N<0.002% Non-oriented electrical steel sheet further comprising

2. The following chemical elements by mass percent: 0<C≦0.0015%, Si: 0.2-1.8%, Mn: 0.2-0.4%, Al: 0.2-0.6%, V: 0.002-0.005%, and N<0.002%; and the balance is Fe and unavoidable impurities. The non-oriented electrical steel sheet according to claim 1 ,

3. 3. The non-oriented electrical steel sheet according to claim 1, wherein the unavoidable impurities satisfy Nb<0.002% and Ti<0.002%.

4. 3. The non-oriented electrical steel sheet according to claim 1, comprising N-containing inclusions as the main inclusions, the N-containing inclusions comprising individual VN, AlN and / or composite VN, AlN, NbN and TiN.

5. 5. The non-oriented electrical steel sheet according to claim 4, wherein the N-containing inclusions have a size of 200-500 nm.

6. 5. The non-oriented electrical steel sheet according to claim 4, having a volume fraction ratio of VN to N-containing inclusions of ≧0.

85.

7. Core loss P≦4.2W / kg 15 / 50 and magnetic induction B ≥ 1.73T 50 The non-oriented electrical steel sheet according to claim 1 or 2, having

8. A manufacturing method for the non-oriented electrical steel sheet according to any one of claims 1 to 7, comprising the following steps: (1) Smelting and casting processes; (2) a process of hot rolling, in which the steel coil obtained after hot rolling is directly introduced into the next process without being subjected to normalizing annealing or coating annealing; (3) pickling to obtain a pickled steel sheet; (4) cold rolling the pickled steel sheet to obtain a cold-rolled steel sheet; and (5) A continuous annealing process, in which the cold rolled steel sheet is heated to the target soak temperature at a heating rate of 50-5000°C / s. A manufacturing method comprising:

9. The method according to claim 8, wherein step (5) satisfies at least one of the following conditions: The target soaking temperature is 500-1100℃; The cold rolled steel sheet is heated to the target soak temperature at a heating rate of 80-550°C / s.

10. The method according to claim 8, wherein step (2) satisfies at least one of the following conditions: During hot rolling, the time of casting the slab in the furnace is controlled at 120-360 minutes, the initial rolling temperature is controlled at 1000-1250°C, the final rolling temperature is controlled at 650-1000°C, and the coiling temperature is controlled at 550-950°C; The hot rolled steel sheet is controlled to have a target thickness of 0.8-3.5 mm; and / or In step (4), the pickled steel sheet is cold rolled in one go to a target cold rolling thickness.

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