Non-oriented electric steel plate with excellent magnetic performance and method for manufacturing the same

Abstract

The present invention provides a non-oriented electric steel plate with good magnetic performance. In addition to Fe and unavoidable impurities, the non-oriented electric steel plate further comprises the following chemical element in mass%: 0 <C≤0.0025%, Si: 0.2-1.6%, Mn: 0.2-0.6%, Al: 0.2-0.6%, V: 0.001-0.008%, N: 0.002-0.0045%, 0<Nb≤0.003% 및 0<Ti≤0.003%. 또한, 본 발명에서는 자기 성능이 양호한 무방향성 전기 스틸 플레이트의 제조방법을 추가로 개시한다. 제조방법은 (1) 제련 및 주조 단계; (2) 열간압연 후, 스틸 코일을 노멀라이징 어닐링이나 커버 어닐링을 실시하지 않고 바로 다음 공정으로 도입하는 열간압연 단계; (3) 산세척 단계; (4) 냉간압연 단계; 및 (5) 냉간압연 스틸 플레이트를 80~1000 ℃ / s의 가열속도로 상온에서 목표 균열온도까지 급속 가열하는 완제품 어닐링 단계를 포함한다. 본 발명의 무방향성 전기 스틸 플레이트는 전자기적 성능이 우수하고, 철손이 적으며, 자기유도율이 높아 철심 제조에 효과적으로 사용될 수 있으며, 대중화 전망 및 활용 가치가 좋다.

Description

Technology Field

[0001] The present invention relates to a steel plate and a method for manufacturing the same, and in particular to a non-oriented electric steel plate and a method for manufacturing the same. Background Technology

[0002] The market and users have long pursued the goal of energy conservation and consumption reduction for iron cores in various home appliances and power tools. In other words, the non-oriented electric steel plates that serve as the raw material for these cores must possess correspondingly high magnetic induction characteristics and low iron loss characteristics.

[0003] Research has revealed that in order to obtain non-oriented electric steel plates with excellent electromagnetic performance, it is necessary to appropriately control the chemical composition of the steel and improve the grain size and texture of the finished steel plates.

[0004] In conventional technology, many researchers have conducted extensive studies on the topic of improving the electromagnetic performance of non-oriented electric steel plates and have achieved certain research results.

[0005] For example, an application titled "Method for manufacturing a high-grade non-oriented electric steel plate" with publication number JP 2008260980 and publication date October 30, 2008, discloses a non-oriented electromagnetic steel plate. In the technical solution disclosed in this application, the grain size and crystal structure of a hot-rolled plate are improved by increasing the exit temperature of the hot-rolled slab, which is generally about 1230°C to 1320°C. The prepared finished steel plate has a good surface condition and high magnetic induction. However, in order to prevent non-metallic inclusions such as S and N from being completely dissolved and dispersed during the process of heating and rolling the slab after raising the slab exit temperature, which could worsen the iron loss of the finished steel plate, this technology also adopts a method of refining molten steel by adding 0.005-0.03% of calcium-containing alloy or rare earth elements, and strictly requires that the content of S and N be less than 0.0015%. This design method not only increases the difficulty of smelting control but also increases production costs and requires special slab heating equipment, so it does not contribute to popularization and application.

[0006] As another example, a Chinese application with publication number CN101343683A, published on January 14, 2009, and titled "Method for manufacturing a non-oriented electric steel plate having low iron loss and high magnetic induction" discloses a method for manufacturing a non-oriented electric steel plate with low iron loss and high magnetic induction. The process steps of the technical solution disclosed in this application are as follows: the heating temperature of the casting is controlled to 900-1150°C, the hot-rolled plate is normalized and pickled, then cold-rolled once to a thickness of 0.50 mm, and finally, stress-relief annealing is performed in a hydrogen-nitrogen mixed gas atmosphere to obtain a non-oriented electric steel plate product with low iron loss and high magnetic induction. The advantage is that the final non-oriented electric steel plate product has good magnetic performance, and P15 / 50 =3.1-3.8 W / kg, B5000=1.69-1.81 T, and the slab contains 1.0-2.0% Si, 0-0.60% Al, 1.5%≤Si+3Al≤3.2%, and does not contain alloying elements such as Sn, Sb, Bi, Cu, Cr, Ni, B, Ca, and Ce, thereby significantly reducing production costs and producing a non-oriented electric steel plate with excellent magnetic performance.

[0007] As another example, a Chinese application with publication number CN104073715A, publication date October 1, 2014, titled "Non-oriented electric steel plate having high magnetic induction and method for manufacturing the same," discloses a non-oriented electric steel plate having high magnetic induction. Magnetic induction. In the technical solution disclosed in this application, by controlling the heating speed of the normalizing heating section and the speed of the normalizing cooling section, and by adopting an appropriate shot blasting and pickling process system, raw materials of excellent plate quality are provided through subsequent processes, and magnetic induction B 50 The magnetic induction can be increased to 200–500 gauss, and the actual physical quality level of iron loss can be increased by 3–5% without adding alloying elements or changing the continuous annealing process. In addition, by optimizing the annealing process, the magnetic performance of the product can be further improved, thereby increasing magnetic induction. Non-oriented electric steel plates with high magnetic induction meet the requirements of existing motors and the high magnetic induction requirements of electric steel for high-efficiency and variable frequency motor cores, improving motor efficiency and reducing energy consumption and product noise.

[0008] However, unlike the existing technical solutions mentioned above, the inventors adopt a new design idea to optimize the chemical composition of the steel and define a reasonable manufacturing process, and expect to obtain a new non-oriented electric steel plate having excellent magnetic performance capable of effectively improving the electromagnetic performance of the non-oriented electric steel plate, reducing iron loss, and increasing magnetic induction. The problem to be solved

[0009] One of the objectives of the present invention is to provide a non-oriented electric steel plate with good magnetic performance. The non-oriented electric steel plate has iron loss P 15 / 50 This is 3.2 W / kg or less, magnetic induction B 50 With a magnetic performance of 1.75 T or higher, it can be effectively utilized in iron core manufacturing, and has very good prospects for popularization and application value in various fields of electrical products and power tools. means of solving the problem

[0010] To achieve the above objective, the present invention provides a non-oriented electric steel plate having good magnetic performance comprising the following chemical elements in mass% in addition to Fe and unavoidable impurities:

[0011] 0 <C_0.0025%, Si: 0.2-1.6%, Mn: 0.2-0.6%, Al: 0.2-0.6%, V: 0.001-0.008%, N: 0.002-0.0045%, 0<Nb≤0.003% 및 0 <Ti≤0.003%.

[0012] Preferably, the non-oriented electric steel plate according to the present invention comprises the following chemical elements in mass%:

[0013] 0 <C≤0.0025%, Si: 0.2-1.6%, Mn: 0.2-0.6%, Al: 0.2-0.6%, V: 0.001-0.008%, N: 0.002-0.0045%, 0<Nb≤0.003%, 0 <Ti≤0.003%, 나머지는 Fe 및 불가피한 불순물이다.

[0014] In the non-oriented electric steel plate according to the present invention, the design principle of each chemical element is as follows.

[0015] C: The non-oriented electric steel plate according to the present invention must not have a C content in the steel that is too high. If the C content of the steel is higher than 0.0025%, a large amount of C-containing inclusions are formed, which significantly increases the magnetic aging of the finished steel plate. Therefore, in the non-oriented electric steel plate according to the present invention, the mass% of C is 0 <C≤0.0025%로 제어한다.

[0016] Si: In the non-oriented electric steel plate according to the present invention, the Si content is medium to low. In the present technical solution, if the Si content is higher than 1.6%, not only does the manufacturing cost of the steel increase, but the magnetic induction of the finished steel plate is also significantly reduced. On the other hand, if the Si content is lower than 0.2%, the effect of effectively reducing iron loss cannot be obtained. Therefore, the mass% of Si in the non-oriented electric steel plate according to the present invention is controlled to 0.2% to 1.6%.

[0017] Mn: If the amount of Mn added to the non-oriented electric steel plate according to the present invention exceeds 0.6%, the good texture of the finished non-oriented electric steel plate is significantly degraded; on the other hand, if the Mn content of the steel is lower than 0.2%, the effect of controlling S-containing inclusions cannot be obtained. Therefore, considering the effect of the Mn content on the physical properties of the steel in the non-oriented electric steel plate according to the present invention, the mass% of Mn is controlled to 0.2% to 0.6%.

[0018] Al: In the non-oriented electric steel plate of the present invention, if the amount of Al added exceeds 0.6%, the fluidity of the molten steel is significantly reduced; and if the Al content in the steel is lower than 0.2%, the effect of effectively reducing iron loss cannot be obtained. Therefore, in order for Al to exert a beneficial effect in the non-oriented electric steel plate according to the present invention, the mass% of Al is controlled to 0.2% to 0.6%.

[0019] V: In the prior art, the V element in non-oriented electric steel plates is an impurity element introduced during the steelmaking process, and its content is strictly controlled. A lower content is better. In contrast, the present invention utilizes V as a beneficial element during the steelmaking process and consciously adjusts its content. To minimize the content of harmful inclusions, the present invention changes from the conventional method of minimizing V content to a method of consciously adding a certain amount of V. By controlling the type and amount of N-containing inclusions along with the adjustment of the manufacturing process, the present invention maximizes the harmless treatment of Nb, V, and Ti content. In this way, reasonable preconditions are realized for controlling the arrangement and combination of chemical components and the type of inclusions that help obtain excellent magnetic performance.

[0020] In the non-oriented electric steel plate according to the present invention, if the V content in the steel is less than 0.001%, the effect of controlling C- and N-containing inclusions cannot be obtained. However, it should be noted that the amount of V element added to the steel should not be too large. If the V element content of the steel is higher than 0.008%, the number of C- and N-containing inclusions containing V will increase significantly and their size will decrease. Therefore, the mass% of V in the non-oriented electric steel plate according to the present invention is controlled to 0.001% to 0.008%.

[0021] N: If the N content in the non-oriented electric steel plate according to the present invention is lower than 0.002%, the effect of reasonably controlling C- and N-containing inclusions cannot be obtained. However, it should be noted that the N content in the steel should not be too high. If the N content in the steel exceeds 0.0045%, the number of N-containing inclusions increases significantly, which inhibits the grain growth of the finished steel plate and degrades the electromagnetic performance of the finished steel plate. Therefore, the mass% of N in the non-oriented electric steel plate according to the present invention is controlled to 0.002% to 0.0045%.

[0022] Meanwhile, considering that it is difficult to obtain a low N element content and that fine AlN inclusions are likely to be generated when the Al content is 0.2 to 0.6%, the inventors add 0.002-0.0045% of N along with 0.001-0.008% of V element to the steel. Here, the main reason for adding V as a beneficial element is as follows. Compared to carbides and nitrides of Al, Nb, Ti, etc., the deterioration effect of V carbides and nitrides on the electromagnetic performance of the finished steel plate is much less, and V carbides and nitrides are relatively stable.

[0023] Nb: In this technical solution, if the Nb content is higher than 0.003%, C- and N-containing inclusions contained in the steel increase abnormally, causing a rapid increase in iron loss of the finished steel plate. Therefore, in this invention, 0 <Nb≤0.003%를 만족하도록 Nb의 함량을 조절한다.

[0024] Ti: In current technical solutions, if the Ti content is higher than 0.003%, C- and N-containing inclusions in the steel also increase abnormally, causing a rapid increase in iron loss of the finished steel plate. Therefore, in the present invention, 0 <Ti≤0.003%를 만족하도록 Ti의 함량을 조절한다.

[0025] Preferably, the non-oriented electric steel plate according to the present invention has a mass% of V of 0.0015 to 0.0045%.

[0026] Preferably, in the non-oriented electric steel plate according to the present invention, the unavoidable impurities include S≤0.002%.

[0027] Unlike conventional design methods of the past, the present invention strictly controls not only the carbon content but also the sulfur content to reduce the formation of carbon-containing inclusions. This is because the higher the sulfur content in the steel, the more sulfur-containing inclusions are formed at the end of solidification or hot rolling of the molten steel, and the fine size of sulfur-containing inclusions degrades the electromagnetic performance of the steel much more than that of nitrogen-containing inclusions. However, it should be noted that the difficulty of controlling the sulfur content is much lower than that of nitrogen. To obtain lower sulfur content, there are many technical means available in actual operational processes, such as limiting the sulfur content of raw materials and auxiliary materials for ironmaking and steelmaking, and deep desulfurization, which involves adding desulfurizing agents during hot metal pretreatment, converter smelting, and RH refining.

[0028] In the above solution, as long as technical conditions and production costs allow, it is better to have as few unavoidable impurities in the steel as possible. If the S content exceeds 0.002%, the number of S-containing inclusions increases significantly, which inhibits the grain growth of the finished steel plate and degrades the electromagnetic performance of the finished steel plate.

[0029] Preferably, the non-oriented electric steel plate according to the present invention comprises inclusions, which are inclusions containing C and / or N and are mainly composed of AlN, VN, VC and V(CN).

[0030] In the present invention, by adopting the chemical element design according to the present invention and carrying out smelting under appropriate smelting conditions, C- and N-containing inclusions can be obtained. The C- and N-containing inclusions contained in the steel are large in size and few in number, and the main inclusions are AlN, VN, VC, and V(CN), and the inclusions also contain small amounts of TiC, TiN, Ti(CN), and NbC, NbN, and Nb(CN).

[0031] Preferably, in the non-oriented electric steel plate according to the present invention, the size of the C- and N-containing inclusions is 200 to 500 nm.

[0032] Preferably, the non-oriented electric steel plate according to the present invention controls inclusions to satisfy the following formula: 1.5 ≤ AlN content / (VN content + VC content + V(CN) content) ≤ 4.0. Using this control is advantageous for grain growth and iron loss reduction of the steel plate during annealing.

[0033] Preferably, the non-oriented electric steel plate according to the present invention has iron loss P 15 / 50 This ≤3.2 W / kg, and magnetic induction B 50 This is ≥1.75 T.

[0034] Accordingly, another objective of the present invention is to provide a method for simply and feasibly manufacturing a non-oriented electric steel plate with good magnetic performance as described above. By using this manufacturing method, good magnetic performance (iron loss P) 15 / 50 ≤3.2 W / kg, magnetic induction B 50 A non-oriented electric steel plate having ≥1.75 T can be obtained.

[0035] To achieve the above objective, the present invention provides a method for manufacturing a non-oriented electric steel plate with excellent magnetic performance comprising the following steps:

[0036] (1) A step of obtaining a slab by smelting and casting molten steel;

[0037] (2) A step of obtaining a steel coil by hot rolling the above slab, wherein the steel coil is introduced directly to the next step without undergoing normalizing annealing or cover annealing after hot rolling;

[0038] (3) A step of obtaining a pickled steel plate by performing acid pickling;

[0039] (4) cold rolling the above pickled steel plate to obtain a cold-rolled steel plate; and

[0040] (5) A continuous annealing step, wherein the cold-rolled steel plate is heated to a target soaking temperature at a heating rate of 80 to 1000 ℃ / s.

[0041] In the present invention, the inventors optimize the chemical composition of the steel, intentionally add V elements to the steel, and strictly limit the content of harmful elements C and N within the steel to effectively control harmful C- and N-containing inclusions. At the same time, based on the necessity of controlling harmful inclusions in the steel, the inventors also define a reasonable manufacturing process. Certified slabs obtained by smelting and casting are subjected to direct pickling and single cold rolling to a target thickness without undergoing normalizing annealing or cover annealing after hot rolling, followed by continuous annealing. By utilizing an electromagnetic induction device with a rapid heating function, a non-oriented electric steel plate with good magnetic performance meeting the design requirements of the present invention can be obtained. The present invention does not impose special restrictions on hot rolling, pickling, and cold rolling, and adheres to the principle of not increasing the manufacturing cost or production difficulty of the steel.

[0042] In addition, while there are some technical solutions in the prior art that do not require normalizing annealing or cover annealing, it should be noted that most of these steels are high-silicon steels with a high Si content. Unlike the prior art, the steel of the present invention is a medium-low silicon steel with a Si content of only 0.2 to 1.6%. Although the present invention uses medium-low silicon steel, it does not require the normalizing annealing or cover annealing treatment.

[0043] In step (5) of the above manufacturing method of the present invention, an electromagnetic induction device having a rapid heating function is used. The device is not limited to longitudinal or transverse magnetism, but the heating capacity must meet the requirement of rapidly heating a cold-rolled steel plate to a target cracking temperature at a heating rate of 80-1000 ℃ / s.

[0044] Compared to conventional annealing methods using gas and electric heating (generally less than 30 °C / s), the present invention adopts an electromagnetic induction heating device equipped with a rapid heating function for continuous annealing to realize the rapid heating of a cold-rolled steel plate to a target cracking temperature in a short time. The heating start temperature can be any temperature lower than the cracking temperature; for example, heating can start at room temperature. By adopting this annealing method, recovery of the cold-rolled steel plate during continuous annealing can be effectively suppressed, and the residual strain accumulation energy of the cold-rolled steel plate before recrystallization is significantly increased, thereby increasing the driving force for accumulation and nucleation, and promoting the nucleation and migration of large-angle grain boundaries. At the same time, the preferred orientation of the crystal nuclei is reduced, and finally <111> / / ND As the strength of the components of the recrystallized structure decreases, magnetic induction increases and iron loss decreases.

[0045] During rapid heating and annealing of cold-rolled steel plates, it is necessary to limit the heating rate of the cold-rolled steel plates to 80–1000 °C / s, preferably 150–850 °C / s, and more preferably 250–750 °C / s, in order to further increase the driving force for nucleation and growth to improve and control the final recrystallization effect, and to ensure that the proportion of harmful grain orientations is low and the grain structure is coarse and uniform after continuous annealing. If the rapid heating rate is too slow (heating rate less than 80 °C / s), the energy stored in the cold-rolled deformation is released too quickly, which does not aid in the subsequent control of a good microstructure. If the rapid heating rate is too fast (heating rate higher than 1000 °C / s), the requirements for equipment capacity become too high, resulting in high equipment costs, and the cold-rolled strip remains in the high-temperature stage for too long, leading to a decrease in the uniformity of the crystal structure.

[0046] Preferably, in the manufacturing method of the present invention, the target cracking temperature in step (5) is 800 to 1000°C.

[0047] Preferably, the manufacturing method of the present invention controls the superheat of the molten steel in the casting process of step (1) to 10 to 35°C and controls the time for transitioning between the solid and liquid phases to 10 seconds to 120 minutes. As the casting of the molten steel proceeds, the casting temperature is in the range of 900 to 1150°C, and the slab is cooled at a rate of 10°C / min or less.

[0048] In the technical solution of the present invention, in order to ensure an excellent precipitation effect of V's carbides and nitrides, it may be desirable to control the degree of superheating of the molten steel during the casting process to within the range of 10 to 35°C and to adjust the transition time between the solid phase and the liquid phase to within the range of 10 seconds to 120 minutes.

[0049] In addition, from the perspective of production efficiency and inclusion size control effects, it is more desirable to control the transition time between the solid and liquid phases to a range of 20 seconds to 50 minutes, more preferably 2 minutes to 50 minutes, and even more preferably 10 minutes to 50 minutes. The premise is that during the casting and solidification process of molten steel, the casting temperature is within the range of 900 to 1150°C and the slab is cooled at a rate of 10°C / min or less.

[0050] Preferably, in the manufacturing method according to the present invention, the time the slab stays in the furnace during hot rolling in step (2) is controlled to 120 to 360 minutes, the initial rolling temperature is 1050 to 1150℃, the final rolling temperature is 650 to 950℃, and the coiling temperature is 500 to 900℃.

[0051] Preferably, the manufacturing method according to the present invention controls the target thickness of the hot-rolled steel plate to 0.8 to 3.5 mm in step (2); and obtains the target cold-rolled thickness by a single cold rolling in step (4). Effects of the invention

[0052] The non-oriented electric steel plate with excellent magnetic performance and the method for manufacturing the same according to the present invention have the following advantages and effects compared to the prior art.

[0053] Unlike traditional thinking, the steelmaking process of the present invention regards V as a beneficial element and consciously adjusts the V content.

[0054] In the non-oriented electric steel plate according to the present invention, the inventor has adopted a design that optimizes the ratio of chemical element components. Slabs manufactured by smelting and casting do not require normalizing annealing or cover annealing after hot rolling; instead, pickling and cold rolling are performed directly, followed by rapid heating. By rapidly heating the cold-rolled steel plate to a target cracking temperature at a high heating rate, the electromagnetic performance required by the design of the present invention can be obtained.

[0055] The design idea of ​​the chemical elements of the present invention is completely different from the prior art. Furthermore, the manufacturing method of the present invention is simple and feasible. The manufactured non-oriented electric steel plate has high magnetic induction and low iron loss characteristics, and iron loss P 15 / 5 0 is 3.2 W / kg or less, magnetic induction B 50 Since it is 1.75 T or higher, non-oriented electric steel plates can be effectively used in iron core manufacturing and have good prospects for popularization and utilization value. Brief explanation of the drawing

[0056] Figure 1 is a micrograph of the finished non-oriented electric steel plate of Example 5. Figure 2 is a micrograph of the comparative steel plate of Comparative Example 3. Figure 3 schematically shows the relationship between the average size of carbide and nitride inclusions and iron loss in a finished non-oriented electric steel plate. Specific details for implementing the invention

[0057] Hereinafter, a non-oriented electric steel plate with excellent magnetic performance and a method for manufacturing the same according to the present invention will be described in more detail with reference to the attached drawings and specific embodiments. However, the description and examples do not unduly limit the technical solutions of the present disclosure.

[0058] Examples 1–10 and Comparative Examples 1–3

[0059] The mass percentage of chemical elements of the non-oriented electric steel plates of Examples 1 to 10 and the comparative steel plates of Comparative Examples 1 to 3 is shown in Table 1.

[0060] [Table 1] (wt%, remainder is unavoidable impurities other than Fe and S)

[0061]

[0062] In the present invention, the non-oriented electric steel plates of Examples 1 to 10 and the comparative steel plates of Comparative Examples 1 to 3 were all manufactured by the following steps (1) to (5).

[0063] (1) Smelting and casting were carried out according to the chemical composition ratio of Table 1. During casting, the superheating of the molten steel was controlled to 10 to 35°C, the transition time between the solid and liquid phases was controlled to 10 seconds to 120 minutes, and as the casting of the molten steel progressed, the cooling rate of the slab was controlled to 10°C / min or less within the range of 900 to 1150°C.

[0064] (2) Hot rolling: During hot rolling, the time the slab stays in the furnace is adjusted to 120–360 minutes, the initial rolling temperature is adjusted to 1050–1150℃, the final rolling is performed in 2–8 passes, the final rolling temperature is adjusted to 650–950℃, and the coiling temperature is adjusted to 500–900℃. After hot rolling, the steel coil proceeds directly to the next stage without undergoing normalizing annealing or cover annealing.

[0065] (3) A pickled steel plate was obtained by performing pickling.

[0066] (4) Cold rolling of pickled steel plate: The pickled steel plate was cold rolled once to a target cold rolling thickness of 0.50 mm.

[0067] (5) Continuous annealing: Cold-rolled steel plates were rapidly heated to a target cracking temperature of 800 to 1000°C at a heating rate of 80 to 1000°C / s.

[0068] In the present invention, it should be noted that the chemical composition and related process variables of the non-oriented electric steel plates of Examples 1 to 10 all satisfy the control requirements of the design specifications of the present invention. However, Comparative Examples 1 to 3 have chemical compositions and process variables that do not satisfy the design requirements of the present invention.

[0069] The specific process parameters of the non-oriented electric steel plates of Examples 1 to 10 and the comparative steel plates of Comparative Examples 1 to 3 are shown in Table 2.

[0070] [Table 2]

[0071]

[0072] The finished non-oriented electric steel plates of Examples 1 to 10 and the comparative steel plates of Comparative Examples 1 to 3 were each sampled, and the steel plate samples of Examples 1 to 10 and Comparative Examples 1 to 3 were observed and analyzed. It was found that both the steel of the Examples and the steel of the Comparative Examples contained C- and N--containing inclusions, which were mainly AlN, VN, VC, and V(CN) inclusions, and that small amounts of TiC, TiN, Ti(CN), and NbC, NbN, and Nb(CN) generated from Nb and Ti were also contained.

[0073] Through further analysis and testing, the sizes of C- and N-containing inclusions and the ratio of AlN content (VN content + VC content + V(CN) content) in the steel plates of the examples and comparative examples were obtained, respectively. The relevant observations and analysis results are shown in Table 3 below.

[0074] [Table 3]

[0075]

[0076] Note: In Table 3 above, A* represents the average size of C- and N-containing inclusions. B* represents AlN content / (VN content + VC content + V(CN) content).

[0077] Accordingly, after completing the observation and analysis of the above inclusions, the finally manufactured non-oriented electric steel plates of Examples 1 to 10 and the comparative steel plates of Comparative Examples 1 to 3 were sampled again, and magnetic induction B for the steel plate samples of the Examples and Comparative Examples 50 and iron loss P1 5 / 50 ...was tested. The obtained test results are shown in Table 4 below.

[0078] The relevant performance test methods are as follows.

[0079] Self-induction B 50Test: The iron loss performance test was performed using the Epstein frame method in accordance with the national standard GB / T 3655-2008. The test temperature was a constant 20°C, the sample size was 30 mm x 300 mm, and the target mass was 0.5 kg. The test variable was the magnetic induction B of the steel plates in the examples and comparative examples. 50 am.

[0080] Iron hand P 15 / 50 Test: The iron loss performance test was performed using the Epstein frame method in accordance with the national standard GB / T 3655-2008. The test temperature was a constant 20°C, the sample size was 30 mm x 300 mm, and the target mass was 0.5 kg. The test variable was the iron loss P of the steel plates in the examples and comparative examples. 15 / 50 am.

[0081] Magnetic induction B of the non-oriented electric steel plates of Examples 1 to 10 and the comparative steel plates of Comparative Examples 1 to 3 50 and iron loss P 15 / 50 The test results are shown in Table 4.

[0082] [Table 4]

[0083]

[0084] As shown in Table 4 above, the non-oriented electric steel plates of Examples 1 to 10 according to the present invention have magnetic induction B 50 This ranges from 1.75 to 1.79 T, iron loss P 15 / 50 It has a range of 2.72 to 3.18 W / kg. The non-oriented electric steel plates of Examples 1 to 10 have significantly superior magnetic performance compared to the comparative steel plates of Comparative Examples 1 to 3. Since Comparative Examples 1 to 3 do not satisfy the conditions defined in the present technical plan, the implementation effect of Comparative Examples 1 to 3 is inferior to that of Examples 1 to 10.

[0085] Referring to Tables 1–4, it can be seen that in the case of Comparative Example 1, the V content is 0.0004%, which is lower than the design lower limit of 0.001% of the present invention. The S content is 0.0027%, exceeding the design upper limit of 0.002% of the present invention. Correspondingly, the average size of carbide and nitride inclusions in the steel is 84 nm, which is lower than the design lower limit of 200 nm of the present invention. B* is 0.8, which is lower than the design lower limit of 1.5 of the present invention. Furthermore, since Comparative Example 1 adopts only the conventional heating rate of 15 °C / s for continuous annealing, the electromagnetic performance of the finished comparative steel plate of Comparative Example 1 is poor, and the iron loss P 15 / 50 3.16 W / kg and magnetic induction B 50 is 1.73T. Magnetic induction B 50 It is lower than the design requirements of the present invention.

[0086] In contrast, in Comparative Example 2, the Al content was 0.0025%, which is lower than the design lower limit of 0.2% of the present invention. The N content was 0.0067%, which exceeds the design upper limit of 0.0045% of the present invention. Correspondingly, the average size of carbide and nitride inclusions in the steel was 117 nm, which is lower than the design lower limit of 200 nm of the present invention. B* was 1.3, which is lower than the design lower limit of 1.5 of the present invention. Meanwhile, the superheating degree of the molten steel during casting was 40°C, which exceeds the design upper limit of 35°C of the present invention. When the cooling rate of the slab is limited, the slab temperature is high at 1350°C, which exceeds the design upper limit of 1150°C of the present invention. In addition, since Comparative Example 2 adopts only the conventional heating rate of 15 ℃ / s for continuous annealing, the electromagnetic performance of the finished comparative steel plate of Comparative Example 2 is poor, and the iron loss P 15 / 50 3.41 W / kg and magnetic induction B 50 . is 1.71 T. Iron loss P 15 / 50 and self-induction B 50Both are lower than the design requirements of the present invention.

[0087] In contrast, in Comparative Example 3, the Mn content was 0.65%, exceeding the design upper limit of 0.6% of the present invention. The S content was 0.0042%, exceeding the design upper limit of 0.002% of the present invention. The V content was 0.0008%, which is lower than the design lower limit of 0.001% of the present invention. Correspondingly, the average size of carbide and nitride inclusions in the steel was 52 nm, which is lower than the design lower limit of 200 nm of the present invention. B* was 0.2, which is lower than the design lower limit of 1.5 of the present invention. Furthermore, in Comparative Example 3, the slab temperature when the cooling rate of the slab is limited was 750°C, which is lower than the design lower limit of 900°C of the present invention. Therefore, the finished comparative steel plate of Comparative Example 3 has an iron loss P 15 / 50 This 4.54 W / kg, magnetic induction B 50 The electromagnetic performance is poor at 1.70 T. Iron loss P 15 / 50 and self-induction B 50 Both are lower than the designed requirements of the present invention.

[0088] Figure 1 is a micrograph of the finished non-oriented electric steel plate of Example 5.

[0089] As shown in Fig. 1, in the embodiment of Example 5, the microstructure of the non-oriented electric steel plate was completely recrystallized, and all the recrystallized grains were relatively symmetrical equiaxed grains, and the grain size was coarse and developed.

[0090] Figure 2 is a micrograph of the comparative steel plate of Comparative Example 3.

[0091] As shown in FIG. 2, in the embodiment of Comparative Example 3, the microstructure of the comparative steel was completely recrystallized, but it can be seen that the proportion of equiaxial grains among the recrystallized grains is low, the size is small, and the grain sizes are relatively dispersed. Among them, the large grains are "island grains" that have grown abnormally.

[0092] Figure 3 schematically shows the relationship between the average size of carbide and nitride inclusions and iron loss in a finished non-oriented electric steel plate.

[0093] As shown in FIG. 3, as the average size of carbide and nitride inclusions in the steel increases, the iron loss of the finished non-oriented electric steel plate gradually decreases and remains stable within the range of 200 to 500 nm, satisfying the control requirement of 3.2 W / kg, which is the upper limit designed in the present invention. However, when the size exceeds 500 nm, the iron loss of the finished non-oriented electric steel plate increases as the average size of carbide and nitride inclusions in the steel increases, making it impossible to satisfy the iron loss control requirement designed in the present invention.

[0094] It should be noted that the combination of features of the present disclosure is not limited to the combinations described in the claims or specific embodiments, and that all features of the present disclosure may be freely combined or combined as long as they do not contradict one another.

[0095] It should be noted that the embodiments listed above are merely specific examples of the present disclosure. The present invention is not limited to the above embodiments, and it is evident that all similar variations or modifications that a person skilled in the art can directly derive from or easily substitute from the present invention fall within the scope of protection of the claims of the present invention.

Claims

Claim 1 Non-oriented electric steel plate containing the following chemical elements in mass % in addition to Fe and unavoidable impurities: 0 <C≤0.0025%, Si: 0.2-1.6%, Mn: 0.2-0.6%, Al: 0.2-0.6%, V: 0.001-0.008%, N: 0.002-0.0045%, 0<Nb≤0.003% 및 0<Ti≤0.003%,상기 무방향성 전기 스틸 플레이트는 AlN, VN, VC 및 V(CN)을 주성분으로 하는 C 및 / 또는 N을 포함하는 개재물을 포함하고,상기 개재물은 1.5≤AlN 함량 / (VN 함량 + VC 함량 + V(CN) 함량)≤4.0을 만족하는 것을 특징으로 함. Claim 2 delete Claim 3 A non-oriented electric steel plate according to claim 1, characterized in that the mass% of V is 0.0015 to 0.0045%. Claim 4 In claim 1, the above-mentioned unavoidable impurities are a non-oriented electric steel plate containing S≤0.002%. Claim 5 delete Claim 6 A non-oriented electric steel plate according to claim 1, characterized in that the size of the inclusion containing C and / or N is 200 to 500 nm. Claim 7 delete Claim 8 In claim 1, the above-mentioned non-oriented electric steel plate has iron loss P 15 / 50 This is 3.2 W / kg or less, and magnetic induction B 50 Non-oriented electric steel plate characterized by having a thickness of 1.75 T or more. Claim 9 A method for manufacturing a non-oriented electric steel plate according to any one of claims 1, 3, 4, 6 and 8, comprising the following steps: (1) a step of smelting and casting molten steel to obtain a slab; (2) a step of hot-rolling the slab to obtain a steel coil, wherein the steel coil is introduced immediately to the next step without undergoing normalizing annealing or cover annealing after hot-rolling; (3) a step of acid pickling to obtain a pickled steel plate; (4) a step of cold-rolling the pickled steel plate to obtain a cold-rolled steel plate; and (5) a continuous annealing step, wherein the cold-rolled steel plate is heated to a target soaking temperature at a heating rate of 80 to 1000 ℃ / s. Claim 10 A manufacturing method according to claim 9, characterized by satisfying at least one of the following conditions: in step (5), the target cracking temperature is 800-1000℃; in the casting process of step (1), the superheat of the molten steel is 10-35℃, the transition time between the solid and liquid phases is 10 seconds to 120 minutes, the casting temperature is 900-1150℃, and the slab is cooled at a rate of 10℃ / min or less; in step (2), the residence time of the slab in the furnace during hot rolling is 120-360 minutes, the initial rolling temperature is 1050-1150℃, the final rolling temperature is 650-950℃, and the coiling temperature is 500-900℃; and in step (2), the target thickness of the hot-rolled steel plate is 0.8-3.5 mm. and / or in step (4) above, the pickled steel plate is cold-rolled once to the target cold-rolled thickness.

Images