Method for improving cold rolling processing performance of high-silicon non-oriented silicon steel

Abstract

A method for improving cold rolling processability of high-silicon non-oriented silicon steel belongs to the technical field of non-oriented silicon steel manufacturing, and comprises the following steps: heating a continuous casting billet with the silicon content of not less than 3.2% by mass and the thickness of 70-240mm, preserving heat in a furnace, removing surface oxide scale by using high-pressure water after discharging, and performing rough rolling to obtain an intermediate billet, removing oxide scales on the surface through high-pressure water, performing finish rolling to obtain a hot-rolled plate, cooling the hot-rolled plate through laminar water, and coiling to obtain a hot-rolled plate coil; the hot-rolled plate coil is put into a cover type annealing furnace to be subjected to annealing treatment, the soaking time t meets the condition that t = 15 + (690-T) * (0.3-0.5) h, the atmosphere in the furnace is hydrogen, the hot-rolled plate coil is taken out of the cover type annealing furnace after being cooled to the room temperature, and a hot-rolled annealed plate coil is obtained; and after being uncoiled, the hot-rolled and annealed plate coil is sequentially subjected to acid pickling and cold rolling in an acid pickling and cold rolling continuous rolling unit, and the cold-rolled steel plate with the thickness of 0.20-0.50 mm is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of non-oriented silicon steel manufacturing, and in particular relates to a method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel. Background Art

[0002] High silicon non-oriented silicon steel is mainly used in large generators, high-efficiency motors and compressors, and new energy vehicle drive motors. Its manufacturing process generally includes smelting molten steel, continuous casting, hot rolling, normalizing, pickling, cold rolling, annealing, and coating insulation. The magnetic properties are demanding and the manufacturing technology is difficult. In particular, when the mass percentage of silicon in electrical steel is greater than 3.2%, the cold rolling deformation resistance is very large. Therefore, the hot-rolled plate needs to be normalized before cold rolling to promote the recrystallization of the hot-rolled deformation structure and reduce the deformation resistance. In addition, there are fibrous elongated deformed grains in the hot-rolled plate of high silicon non-oriented electrical steel. By normalizing the hot-rolled plate, the recrystallization of these deformed grains is promoted, which helps to prevent the final product from having "corrugated" defects. However, normalizing the hot-rolled plate makes the recrystallized grains coarser, and severe edge cracks or even broken strips occur during the cold rolling process, which requires edge trimming, which not only reduces the yield rate, but also increases the difficulty of production. In addition, in the production of high silicon non-oriented silicon steel, cold rolling edge cracks have become the biggest bottleneck of the cold rolling process. There are multiple edge cracks on the end of the steel coil, and the edge crack depth is greater than 5mm, and the edge crack length is greater than 10mm, which causes the rolling mill speed to be low, seriously restricting the machine hour output and rolling stability. Therefore, how to reduce cold rolling edge cracks has become a very important problem that needs to be solved in the manufacture of high silicon non-oriented electrical steel.

[0003] Patent CN110565022B discloses a method for manufacturing high-grade non-oriented electrical steel. The weight percentage of its components is: Si: 2.9-3.5%, Mn: 0.15-1.0%, Al: 0.5-1.5%, C≤0.0040%, S≤0.0060%, Ti≤0.0030%, N≤0.0040%, and the total content of other impurities V, Nb, B, Ca, Mo, Ni is controlled below 0.02%, and the rest is Fe and unavoidable impurities. The ingot is rolled into a hot-rolled plate with a thickness of 2.0 to 3.0 mm, and then normalized at 900 to 1050°C before rolling. During the rolling process, the edge cracks are cut off, and the edge of the strip is trimmed online by 2 to 10 mm. At this time, the temperature of the strip is above 100°C, and the trimming process ensures that the rolling process does not stop. This operation avoids the process of cutting the edge cracks in the offline preparation unit, reduces the shear stress of cold cutting, and the final finished product thickness is 0.5 mm. This method reduces the risk of strip breakage caused by cold rolling edge cracks through online trimming, but increases the production difficulty, reduces production efficiency, and significantly reduces the yield rate.

[0004] Patent CN105396879A discloses a method for controlling edge cracks in cold rolling of high-grade non-oriented silicon steel. This technology requires reducing the load distribution of the first stand from 33% to 36% when the system automatically distributes it to 25% to 30%, which can reduce the edge cracks at the exit of the first stand; setting the UCMW rolling mill working roll shifting value to -40 to 20 mm can effectively reduce the edge stress of the strip, avoid the edge cracks of high-grade non-oriented silicon steel during cold rolling, improve the production capacity of high-grade non-oriented silicon steel cold rolling, and ensure the quality of high-grade non-oriented silicon steel. This technology reduces the edge stress by optimizing the cold rolling mill parameter settings to avoid edge cracks during cold rolling.

[0005] Patent CN114369761A discloses a thin gauge non-oriented silicon steel and its preparation method. Its weight percentage is: C≤0.005%, Si: 2.0~4.0%, Mn: 0.20~2.0%, P≤0.02%, S≤0.005%, Al: 0.3~1.4%, N≤0.005%, Ti≤0.005%, Nb≤0.005%, and (Si+1.3Al) / Mn≥2.1%, 3.0%≤Si+Mn≤4.4%, and the rest is iron and inevitable impurities. After continuous casting, it is rough rolled at 900~1150℃ and fine rolled at 800~950℃ to obtain a 2mm thick hot-rolled plate, normalized at 760~840℃, trimmed, and then cold-rolled to 0.2mm in one step using a twenty-roll mill, and finally annealed at 830~880℃ to obtain a finished product. This method prevents large edge cracks by controlling the first cold rolling reduction rate to less than 18% and the last cold rolling reduction rate to less than 20%. This method requires trimming of the normalized plate and has strict requirements on the cold rolling reduction procedure and reduction amount, which is not conducive to the production capacity of the rolling mill and the improvement of production efficiency. Moreover, it can only prevent large edge cracks, but cannot inhibit the generation of medium and small cracks.

[0006] Patent CN116213458A discloses a method for improving the edge quality of cold-rolled high-grade non-oriented silicon steel for new energy vehicle drive motors. It includes: controlling the pickling time t of the hot-rolled raw material to: T×Si% / 600≤t≤T×Si% / 300; setting the shifting amount of the intermediate roll of the continuous rolling mill to 30-80mm; the ratio L / R of the length L of the working roll of the continuous rolling mill to the radius of curvature R of the working roll surface is controlled within the range of -0.25≤L / R≤-0.15. By optimizing the pickling time of the hot-rolled coil, adopting a reasonable working roll profile size, and adjusting the shifting amount of the intermediate roll, the edge wave generation is minimized while suppressing the edge cracking of the cold-rolled edge, and the cold-rolled edge quality of the high-grade non-oriented silicon steel for new energy vehicle drive motors is improved without cutting the hot-rolled raw material, achieving efficient production, reducing the amount of edge cutting after cold rolling, and improving the yield rate.

[0007] Patent CN116411152A discloses a normalizing method for non-oriented electrical steel. For non-oriented silicon steel with a composition range of: C≤0.004%, Si: 2.2-4.0%, Mn: 0.1-1.2%, Al: 0.1-1.2%, S≤0.01%, Ti≤0.005%, Nb≤0.005%, the specific normalizing process is: heating the hot-rolled plate to have a target temperature, heating the hot-rolled plate of non-oriented electrical steel with a set chemical composition to have a target temperature; under the conditions of the target temperature and a first set time, the heated hot-rolled plate is heated evenly; at a second set time, Under the above conditions, the hot-rolled plate after homogenization is self-homogenized and then cooled to obtain a normalized substrate; wherein the normalization temperature and time are calculated according to the composition, specifically, the target temperature = 1133-66.67×[Si]+66.67×[Mn]-33.33×[Al], the first set time = -44.18+25.45×[Si]+15.00×[Mn]+11.36×[Al], the second set time = 188.18-25.45×[Si]-15.00×[Mn]-11.36×[Al]. Since the target temperature of the normalization process in this technology is still relatively high, the equiaxed grain size obtained after normalization is still relatively coarse. This is not conducive to the improvement of the toughness and plasticity of the steel plate, and the risk of cold-rolled edge cracking or strip breakage cannot be completely avoided.

[0008] In summary, since the silicon content of high-silicon non-oriented silicon steel is relatively high and the deformation resistance during the cold rolling process is very large, it is necessary to normalize the hot-rolled plate before cold rolling. However, there are often coarse equiaxed grains in the normalized plate, and the toughness and plasticity of the steel plate are poor. In the cold rolling process, severe cracking and even strip breakage of the cold-rolled edge often occur, as well as the resulting trimming treatment and reduced yield rate. It can be seen from the above patented technology that in order to reduce edge cracking, the existing means need to strictly control the normalization process, trimming treatment, pass reduction rate distribution, pickling process, roll configuration, etc., and the production process is complicated and difficult to control. In addition, since the normalized plate still contains some relatively coarse equiaxed recrystallized grains, further improvement of toughness and plasticity is hindered. Therefore, it is necessary to effectively regulate the grain structure of the steel plate before cold rolling, and based on this, develop a new method to improve the cold rolling processing performance of high-silicon non-oriented silicon steel. Summary of the invention

[0009] In view of the problem of serious edge cracks occurring during the cold rolling process of high-silicon non-oriented silicon steel, the present invention provides a method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel. By combining the hot rolling technology with the hood annealing technology to regulate the hot rolling and annealing structures, a gradient structure consisting of fine equiaxed crystals on the surface of the steel plate and flat recrystallized grains inside the steel plate is finally obtained in the hot-rolled annealed plate. This gradient structure can effectively prevent the nucleation and expansion of cracks, thereby significantly improving the cold rolling plastic toughness of high-silicon non-oriented silicon steel and avoiding edge cracks during the cold rolling process.

[0010] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0011] (1) heating a continuous casting billet having a silicon content of not less than 3.2% by mass and a thickness of 70 to 240 mm to 1060 to 1100° C., keeping the billet in a furnace for 90 to 180 minutes, removing the surface iron oxide scale with high-pressure water after the billet is taken out of the furnace, and then performing rough rolling, with the starting rolling temperature of 1020 to 1070° C. and the final rolling temperature of 930 to 980° C., to obtain an intermediate billet having a thickness of 20 to 30 mm;

[0012] (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale by high-pressure water, with the starting rolling temperature of 890-940° C. and the final rolling temperature of 790-840° C. to obtain a hot-rolled plate with a thickness of 2.4-2.8 mm, and then the hot-rolled plate is cooled to 500-570° C. by laminar water and then coiled to obtain a hot-rolled coil;

[0013] (3) placing the hot-rolled coil into a bell-type annealing furnace for annealing, wherein the heating rate in the heating section is 20 to 35° C. / h, the temperature T in the soaking section is 620 to 690° C., the soaking time t satisfies t=15+(690-T)×(0.3 to 0.5)h, the cooling rate in the cooling section is 15 to 40° C. / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, the coil is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil;

[0014] (4) After the hot-rolled annealed coil is uncoiled, it is pickled and cold-rolled in a pickling cold rolling mill to obtain a cold-rolled steel plate with a thickness of 0.20 to 0.50 mm.

[0015] In the step (1), the chemical composition of the continuous casting billet is as follows by weight percentage: Si: 3.2-4.1%, Mn: 0.20-0.55%, Al: 0.2-1.5%, C≤0.0027%, S≤0.0025%, N≤0.0020%, O≤0.0010%, Sn or Sb or Sn+Sb≤0.15%, and the remainder is Fe and unavoidable impurities.

[0016] In step (2), the surface layer of the hot-rolled coil is fine equiaxed grains with an average grain size of 10 to 25 μm, the interior of the steel plate is severely elongated fibrous deformed grains, and the equiaxed grain area on the surface of the steel plate accounts for 5 to 18% of the entire steel plate thickness.

[0017] In the step (3), the surface layer of the steel plate of the obtained hot-rolled annealed coil is equiaxed grains with an average grain size of 30 to 50 μm.

[0018] In the step (3), the interior of the steel plate of the obtained hot-rolled annealed coil is flat recrystallized grains, the average width of the flat recrystallized grains is 35 to 75 μm, and the average aspect ratio of the flat recrystallized grains is 2 to 6.

[0019] In the step (3), the equiaxed grain area on the surface of the steel plate of the obtained hot-rolled annealed coil accounts for 20 to 55% of the entire steel plate thickness.

[0020] In the step (4), the pickling solution is a hydrochloric acid aqueous solution with a mass concentration of 1 to 2%, and the pickling temperature is 50 to 85°C.

[0021] In the step (4), the pickled plate needs to be preheated to 70-100° C. before the first cold rolling in the cold rolling process.

[0022] The control principle of the process parameters of each process in the present invention is as follows:

[0023] (1) The mass percentage of silicon in steel is 3.2-4.1%. If the silicon content is higher than 4.1%, the toughness and plasticity of the steel will deteriorate sharply, and the strip will break during the cold rolling process; if the silicon content is lower than 3.2%, the toughness and plasticity of the steel are good, and there is no need to use this technology to improve the cold rolling processing performance. If the mass percentage of aluminum is higher than 1.5%, it is easy to block the water nozzle and continuous casting production cannot be carried out. Carbon, sulfur, oxygen, and nitrogen are harmful impurities that damage magnetic properties. They are easy to form non-magnetic compounds such as cementite, manganese sulfide, aluminum oxide, and aluminum nitride, so their content should be strictly controlled. Sn and Sb elements help improve the magnetic properties of steel, but if the mass percentage of Sn or Sb or Sn+Sb exceeds 0.15%, gray streak defects will appear on the surface of the steel plate.

[0024] (2) The purpose of heating at 1060-1100°C and holding in the furnace for 90-180 minutes is to make the temperature of the steel billet uniform and reduce the deformation resistance of the steel billet during hot rolling. If the heating temperature is too high and the holding time is too long, on the one hand, the grains will be significantly coarsened, resulting in crease defects on the hot rolling edge, and on the other hand, severe surface oxidation will increase the difficulty of removing the oxide scale. If the heating temperature is too low and the holding time is too short, the temperature of the steel billet will be uneven, which will increase the difficulty of controlling the hot rolling thickness and plate shape.

[0025] (3) The purpose of setting the starting temperature of rough rolling to 1020-1070°C, the final rolling temperature to 930-980°C, and the intermediate billet thickness to 20-30 mm is to ensure the subsequent finishing rolling temperature and reduce the finishing rolling pressure.

[0026] (4) The start rolling temperature of the finishing rolling is 890-940℃, the final rolling temperature is 790-840℃, and laminar cooling is performed after hot rolling, and the coiling temperature is 500-570℃. The purpose is to use the lower temperature hot rolling to promote the shear deformation of the surface layer of the hot-rolled plate and induce dynamic recrystallization, so as to obtain more fine equiaxed recrystallized grains on the surface layer of the steel plate, and at the same time, to prevent the formation of coarse equiaxed grains inside the hot-rolled plate due to dynamic recrystallization, and to ensure that a large number of fibrous elongated deformation grains are obtained inside the steel plate; the use of a lower coiling temperature can prevent the growth of equiaxed grains on the surface layer of the hot-rolled plate, and prevent the formation of coarse equiaxed grains inside the hot-rolled plate due to static recrystallization. Through the linkage control of the start rolling temperature, the final rolling temperature and the coiling temperature, it is ensured that the hot-rolled plate obtains a gradient structure consisting of more fine equiaxed grains on the surface layer and fibrous deformation grains inside. If the finishing rolling start temperature, final rolling temperature and coiling temperature are too high, a mixed structure consisting of coarse equiaxed grains on the surface and partially recrystallized equiaxed grains inside will be obtained; if the finishing rolling start temperature and final rolling temperature are too low, the fine equiaxed grains on the surface will decrease sharply and the deformed grains inside will increase sharply.

[0027] (5) The purpose of controlling the thickness of the hot-rolled plate to 2.4-2.8 mm is to reduce the subsequent cold rolling load while ensuring the toughness and plasticity of the cold rolling process. The cold rolling processing performance of steel with a ferrite structure shows a significant thickness effect. If the thickness of the hot-rolled plate is too large, the tendency of edge cracking during the cold rolling process increases; if the thickness of the hot-rolled plate is too small, the thickness accuracy and plate shape control difficulty during the hot rolling process increase sharply.

[0028] (6) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment, and the heating rate in the heating stage is 20-35°C / h. If the heating rate is too low, the production efficiency is low, which limits the production capacity of the furnace; if the heating rate is too high, the temperature gradient between the outside and inside of the steel coil and between the upper and lower parts will increase, resulting in increased stress between the steel plates and steel sticking. The temperature T in the soaking section is 620-690°C, and the soaking time t satisfies t=15+(690-T)×(0.3-0.5)h. If the soaking section temperature is too high and the soaking time is too long, on the one hand, the equiaxed grains on the surface of the steel plate will grow rapidly, so it is difficult to obtain fine equiaxed grains; on the other hand, the deformed grains inside the steel plate are transformed into coarse equiaxed grains due to rapid static recrystallization, and it is difficult to obtain flat recrystallized grains. Therefore, it is impossible to obtain a gradient grain structure consisting of fine equiaxed crystals on the surface of the steel plate and flat recrystallized grains inside the steel plate, which deteriorates the toughness and plasticity of the steel plate and causes serious edge cracks during the cold rolling process. If the temperature of the soaking section is too low and the soaking time is too short, the deformed grains inside the steel plate cannot be fully recrystallized and are retained, and cannot be completely transformed into flat recrystallized grains. The cooling rate of the cooling section is 15-40℃ / h. If the cooling rate is too low, the production efficiency is low, which limits the production capacity of the furnace; if the cooling rate is too high, the temperature gradient between the outside and inside of the steel coil and between the upper and lower parts will increase, resulting in increased stress between the steel plates and steel sticking. The purpose of using hydrogen atmosphere in the heating section, soaking section, and cooling section is to utilize the high heat transfer efficiency of hydrogen and prevent further oxidation and nitridation of the steel plate in the furnace.

[0029] (7) After the hot-rolled annealed coil is unrolled, it is pickled and cold rolled in the pickling cold rolling mill. Since the hydrogen reducing atmosphere is used in the bell-type annealing furnace, the iron oxide scale on the surface of the steel plate is largely reduced to iron, leaving only a small amount of iron oxide scale debris. Therefore, a relatively low concentration of 1-2% hydrochloric acid aqueous solution can be used as the pickling liquid to remove it completely, and a relatively high pickling temperature of 50-85°C is used to improve the pickling efficiency. Since the pickled steel plate needs to move for a certain period of time before it reaches the cold rolling mill, there is a temperature drop in this process. Therefore, the pickled plate needs to be preheated to 70-100°C before the first cold rolling process in the cold rolling process, in order to reduce the deformation resistance and further improve the toughness and plasticity of the steel plate. The target thickness of the steel plate after cold rolling is 0.20-0.50mm, which is the conventional rolling thickness of the existing pickling mill. If the target thickness is too small, the deformation resistance increases sharply, and the strip is prone to breakage during the continuous rolling process, and smooth production cannot be achieved.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The technology of the present invention ensures that the hot-rolled plate obtains a gradient structure consisting of a large number of fine equiaxed grains on the surface and internal fibrous deformation grains through the coordinated control of the heating, rough rolling, finishing rolling and coiling process parameters, and then through the coordinated control of the hood annealing process parameters, it ensures that the hot-rolled annealed plate coil obtains a gradient grain structure consisting of fine equiaxed grains on the surface of the steel plate and flat recrystallized grains inside the steel plate. This gradient structure is different from the equiaxed recrystallization structure obtained by traditional normalizing treatment, has good deformation coordination ability, can effectively prevent the nucleation and lateral expansion of cracks, thereby significantly improving the cold rolling plastic toughness of high-silicon non-oriented silicon steel.

[0032] 2. The technology of the present invention avoids the occurrence of edge cracks during the cold rolling process, and thus significantly reduces the risk of strip breakage caused by edge cracks during the cold rolling process, so that not only does the cold rolling process not require edge trimming, but also improves the yield rate and production efficiency, and there is no need to strictly control the distribution of pass reduction rates and roll configuration during the cold rolling process, which reduces the difficulty of cold rolling production and makes it simple and easy to operate. Since the occurrence of edge cracks is avoided, the method of the present application helps to improve the rolling stability of the cold rolling mill, thereby increasing the rolling speed and machine-hour output of the cold rolling mill, and further improving production efficiency. Since the required soaking temperature of the hood annealing furnace is significantly lower than the soaking temperature of the traditional large-scale continuous normalizing furnace for hot-rolled plates, this technology is conducive to energy saving and consumption reduction, and reduces production costs.

[0033] 3. Unlike the thick iron scale on the surface of the conventional normalized plate, the technology of the present invention adopts a hydrogen reducing atmosphere in the bell-type annealing furnace, so the iron scale on the surface of the steel plate is largely reduced to iron, leaving only a small amount of iron scale debris, so it can be completely removed by using a low-concentration hydrochloric acid aqueous solution as the pickling liquid, which helps to reduce the amount of hydrochloric acid used and reduce the pickling cost. In addition, since the bell-type annealing furnace is cheaper than the traditional large-scale continuous normalizing furnace for hot-rolled plates, it is also helpful to reduce equipment investment and equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 Typical metallographic structure photograph of the longitudinal section of the hot-rolled plate in Example 1 of the present invention;

[0035] Figure 2 Typical metallographic structure photograph of the longitudinal section of the hot-rolled annealed sheet in Example 1 of the present invention;

[0036] Figure 3 Typical appearance photos of the edge of the cold-rolled sheet in Example 1 of the present invention;

[0037] Figure 4 Typical metallographic structure photograph of the longitudinal section of the hot-rolled annealed sheet in Example 2 of the present invention;

[0038] Figure 5Typical appearance photos of the edge of the cold-rolled sheet in Example 2 of the present invention;

[0039] Figure 6 Typical appearance photos of the edge of the cold-rolled sheet in Example 3 of the present invention;

[0040] Figure 7 Typical metallographic structure photograph of the longitudinal section of the hot-rolled plate in Comparative Example 1 of the present invention;

[0041] Figure 8 Typical metallographic structure photograph of the longitudinal section of the hot-rolled annealed sheet in Comparative Example 1 of the present invention;

[0042] Fig. 9 Typical appearance photos of the edge of the cold-rolled sheet in Comparative Example 1 of the present invention;

[0043] Fig.10 Typical metallographic structure photograph of the longitudinal section of the hot-rolled annealed sheet in Comparative Example 2 of the present invention;

[0044] Fig.11 A typical appearance photo of the edge of the cold-rolled sheet in Comparative Example 2 of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. The following are preferred embodiments of the present invention.

[0046] The equipment model used for the metallographic structure observation involved in the present invention is Leica DM2500 M metallographic microscope. The appearance morphology photos of the edge of the cold-rolled plate involved in the present invention were obtained by taking photos with a HUAWEI Mate 50Pro mobile phone. The pendulum impact tester model used for the impact energy detection of the hot-rolled annealed plate involved in the present invention is SANS ZBC2452-B. A sample with a length of 5 cm and a width of 10 mm was cut parallel to the initial hot rolling direction, and an impact sample with a 45° V-notch and a depth of 2 mm was machined. The impact direction is perpendicular to the initial hot rolling direction, and the unit of impact energy is J, which is averaged according to three impact samples. Before the impact test, the sample was kept in hot water at 85±15°C for 10 minutes.

[0047] The following are examples and comparative examples of the present invention.

[0048] Example 1

[0049] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0050] (1) The chemical composition of the continuous casting billet is as follows by weight: Si: 3.2%, Mn: 0.20%, Al: 0.25%, C: 0.0020%, S: 0.0015%, N: 0.0008%, O: 0.0005%, Sn: 0.06%, the balance is Fe and unavoidable impurities, and the thickness is 230 mm. The continuous casting billet is heated to 1070°C, kept in the furnace for 120 min, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1020°C, and the final rolling temperature is 930°C, to obtain an intermediate billet with a thickness of 20 mm.

[0051] (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale with high-pressure water. The starting rolling temperature is 890°C and the final rolling temperature is 790°C to obtain a 2.4 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 510°C with laminar water and coiled to obtain a hot-rolled coil.

[0052] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 13 μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 10% of the entire thickness of the steel plate. The metallographic structure of the longitudinal section of the hot-rolled plate is shown in Figure 1 .

[0053] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 20°C / h, the temperature in the soaking section is 620°C, the soaking time is 43h, the cooling rate in the cooling section is 15°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0054] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 32μm. The interior of the steel plate is flat recrystallized grains with an average width of 45μm and an average aspect ratio of 5. The equiaxed grain area on the surface of the steel plate accounts for 23% of the entire thickness of the steel plate. See the metallographic structure of the longitudinal section of the hot-rolled annealed plate for details. Figure 2 The impact work of hot rolled annealed sheets is shown in Table 1.

[0055] (4) After the hot-rolled annealed coil is unrolled, it is pickled and cold-rolled in the pickling cold rolling unit. The pickling solution is a hydrochloric acid aqueous solution with a mass concentration of 1%. The pickling temperature is 50°C. Before the first cold rolling process, the pickled plate needs to be preheated to 70°C. The thickness of the steel plate after cold rolling is 0.50mm. The appearance of the edge of the cold-rolled plate is shown in Figure 3 , no edge cracking occurred.

[0056] Example 2

[0057] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0058] (1) The chemical composition of the continuous casting billet is as follows by weight: Si: 3.4%, Mn: 0.45%, Al: 1.0%, C: 0.0024%, S: 0.0022%, N: 0.0010%, O: 0.0006%, Sb: 0.07%, the balance is Fe and unavoidable impurities, and the thickness is 230 mm. The continuous casting billet is heated to 1100°C, kept in the furnace for 180 min, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1070°C, and the final rolling temperature is 980°C, to obtain an intermediate billet with a thickness of 30 mm.

[0059] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then fine rolling is performed. The starting rolling temperature is 940°C and the final rolling temperature is 838°C to obtain a 2.5 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 570°C by laminar water and then coiled to obtain a hot-rolled coil.

[0060] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 20μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 15% of the entire steel plate thickness.

[0061] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 35°C / h, the temperature in the soaking section is 690°C, the soaking time is 15h, the cooling rate in the cooling section is 35°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0062] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 45μm. The interior of the steel plate is flat recrystallized grains with an average width of 66μm and an average aspect ratio of 2.5. The equiaxed grain area on the surface of the steel plate accounts for 27% of the entire steel plate thickness. See the metallographic structure of the longitudinal section of the hot-rolled annealed plate for details. Figure 4 The impact work of hot rolled annealed sheets is shown in Table 1.

[0063] (4) After the hot-rolled annealed coil is unrolled, it is pickled and cold-rolled in the pickling cold rolling unit. The pickling solution is a hydrochloric acid aqueous solution with a mass concentration of 2%. The pickling temperature is 65°C. Before the first cold rolling process, the pickled plate needs to be preheated to 90°C. The thickness of the steel plate after cold rolling is 0.35mm. The appearance of the edge of the cold-rolled plate is shown in Figure 5 , no edge cracking occurred.

[0064] Example 3

[0065] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0066] (1) The chemical composition of the continuous casting billet is as follows by weight: Si: 4.10%, Mn: 0.55%, Al: 1.0%, C: 0.0015%, S: 0.0010%, N: 0.0006%, O: 0.0007%, Sn: 0.07%, Sb: 0.08%, the remainder is Fe and unavoidable impurities, and the thickness is 220 mm. The continuous casting billet is heated to 1090°C, kept in the furnace for 150 min, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1050°C, and the final rolling temperature is 970°C, to obtain an intermediate billet with a thickness of 30 mm.

[0067] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then finish rolling is performed. The starting rolling temperature is 920°C and the final rolling temperature is 830°C to obtain a 2.6 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 560°C by laminar water and then coiled to obtain a hot-rolled coil.

[0068] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 24μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 16% of the entire steel plate thickness.

[0069] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing. The heating rate in the heating section is 30°C / h, the temperature in the soaking section is 680°C, the soaking time is 18h, the cooling rate in the cooling section is 40°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0070] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 46 μm, and the interior of the steel plate is flat recrystallized grains with an average width of 71 μm and an average aspect ratio of 3. The equiaxed grain area on the surface of the steel plate accounts for 45% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0071] (4) After the hot-rolled annealed coil is unrolled, it is pickled and cold-rolled in the pickling cold rolling unit. The pickling solution is a hydrochloric acid aqueous solution with a mass concentration of 1.5%. The pickling temperature is 80°C. Before the first cold rolling process, the pickled plate needs to be preheated to 100°C. The thickness of the steel plate after cold rolling is 0.25mm. The appearance of the edge of the cold-rolled plate is shown in Figure 6 , no edge cracking occurred.

[0072] Example 4

[0073] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0074] (1) The chemical composition of the continuous casting billet is as follows by weight: Si: 3.50%, Mn: 0.35%, Al: 0.51%, C: 0.0025%, S: 0.0024%, N: 0.0018%, O: 0.0010%, Sn: 0.15%, the balance is Fe and unavoidable impurities, and the thickness is 70 mm. The continuous casting billet is heated to 1090°C, kept in the furnace for 90 minutes, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1050°C, and the final rolling temperature is 960°C, to obtain an intermediate billet with a thickness of 20 mm.

[0075] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then fine rolling is performed. The starting rolling temperature is 900°C and the final rolling temperature is 790°C to obtain a 2.75 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 570°C by laminar water and then coiled to obtain a hot-rolled coil.

[0076] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 13μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 8.5% of the entire steel plate thickness.

[0077] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 24°C / h, the temperature in the soaking section is 650°C, the soaking time is 35h, the cooling rate in the cooling section is 17°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0078] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 32μm, and the interior of the steel plate is flat recrystallized grains with an average width of 45μm and an average aspect ratio of 6. The surface equiaxed grain area accounts for 25% of the entire steel plate thickness. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0079] (4) The hot-rolled annealed coil is pickled and cold-rolled in the pickling cold rolling mill. The pickling solution is a hydrochloric acid aqueous solution with a mass concentration of 1.3%. The pickling temperature is 85°C. The temperature of the steel plate during the first cold rolling process is 75°C. The thickness of the steel plate after cold rolling is 0.20 mm. The appearance of the edge of the cold-rolled plate is shown in the following figure. Figure 6 , no edge cracking occurred.

[0080] Example 5

[0081] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0082] (1) The chemical composition of the continuous casting billet is as follows by weight: Si: 3.90%, Mn: 0.35%, Al: 0.51%, C: 0.0025%, S: 0.0024%, N: 0.0018%, O: 0.0010%, Sn: 0.15%, the balance is Fe and unavoidable impurities, and the thickness is 70 mm. The continuous casting billet is heated to 1090°C, kept in the furnace for 90 minutes, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1050°C, and the final rolling temperature is 960°C, to obtain an intermediate billet with a thickness of 20 mm.

[0083] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then fine rolling is performed. The starting rolling temperature is 900°C and the final rolling temperature is 790°C to obtain a 2.75 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 570°C by laminar water and then coiled to obtain a hot-rolled coil.

[0084] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 13μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 8.5% of the entire steel plate thickness.

[0085] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 32°C / h, the temperature in the soaking section is 620°C, the soaking time is 50h, the cooling rate in the cooling section is 36°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0086] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 37μm, and the interior of the steel plate is flat recrystallized grains with an average width of 55μm and an average aspect ratio of 3.5. The equiaxed grain area on the surface of the steel plate accounts for 41% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0087] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 1.7%. The pickling temperature was 82°C. The temperature of the steel plate during the first cold rolling process was 83°C. The thickness of the steel plate after cold rolling was 0.20 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1, and no edge cracking occurred.

[0088] Example 6

[0089] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0090] (1) The chemical composition of the continuous casting billet is as follows by weight: Si: 4.0%, Mn: 0.51%, Al: 1.4%, C: 0.0015%, S: 0.0010%, N: 0.0006%, O: 0.0007%, Sn: 0.07%, Sb: 0.03%, the balance is Fe and unavoidable impurities, and the thickness is 210 mm. The continuous casting billet is heated to 1090°C, kept in the furnace for 150 min, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1050°C, and the final rolling temperature is 970°C, to obtain an intermediate billet with a thickness of 30 mm.

[0091] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then finish rolling is performed. The starting rolling temperature is 920°C and the final rolling temperature is 830°C to obtain a 2.6 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 560°C by laminar water and then coiled to obtain a hot-rolled coil.

[0092] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 24μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 16% of the entire steel plate thickness.

[0093] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 25°C / h, the temperature in the soaking section is 625°C, the soaking time is 47h, the cooling rate in the cooling section is 40°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0094] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 38μm, and the interior of the steel plate is flat recrystallized grains with an average width of 69μm and an average aspect ratio of 4. The equiaxed grain area on the surface of the steel plate accounts for 55% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0095] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 1.8%. The pickling temperature was 80°C. The temperature of the steel plate during the first cold rolling process was 100°C. The thickness of the steel plate after cold rolling was 0.25 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1, and no edge cracking occurred.

[0096] Example 7

[0097] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0098] (1) The chemical composition of the continuous casting billet is Si: 3.75%, Mn: 0.50%, Al: 0.85%, C: 0.0020%, S: 0.0020%, N: 0.0010%, O: 0.0006%, Sn: 0.10%, Sb: 0.04%, the balance is Fe and unavoidable impurities, and the thickness is 150 mm. The continuous casting billet is heated to 1100°C, kept in the furnace for 180 minutes, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1070°C, and the final rolling temperature is 980°C, to obtain an intermediate billet with a thickness of 30 mm.

[0099] (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale with high-pressure water. The starting rolling temperature is 935°C and the final rolling temperature is 820°C to obtain a 2.6 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 510°C with laminar water and coiled to obtain a hot-rolled coil.

[0100] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 23μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 16% of the entire steel plate thickness.

[0101] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 22°C / h, the temperature in the soaking section is 640°C, the soaking time is 30h, the cooling rate in the cooling section is 38°C / h, and the atmosphere in the furnace is hydrogen. After cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0102] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 48μm, and the interior of the steel plate is flat recrystallized grains with an average width of 75μm and an average aspect ratio of 2.0. The equiaxed grain area on the surface of the steel plate accounts for 49% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0103] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 2%. The pickling temperature was 65°C. The temperature of the steel plate during the first cold rolling process was 100°C. The thickness of the steel plate after cold rolling was 0.30 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1, and no edge cracking occurred.

[0104] Example 8

[0105] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0106] (1) The chemical composition of the continuous casting billet is Si: 3.35%, Mn: 0.40%, Al: 0.68%, C: 0.0010%, S: 0.0011%, N: 0.0010%, O: 0.0006%, Sb: 0.10%, the balance is Fe and inevitable impurities, and the thickness is 180 mm. The continuous casting billet is heated to 1080°C, kept in the furnace for 140 minutes, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1030°C, and the final rolling temperature is 960°C, to obtain an intermediate billet with a thickness of 28 mm.

[0107] (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale with high-pressure water, with the starting rolling temperature of 900°C and the final rolling temperature of 800°C to obtain a 2.5 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 540°C with laminar water and coiled to obtain a hot-rolled coil.

[0108] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 17μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 6% of the entire steel plate thickness.

[0109] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 23°C / h, the temperature in the soaking section is 660°C, the soaking time is 25h, the cooling rate in the cooling section is 15°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0110] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 38μm, and the interior of the steel plate is flat recrystallized grains with an average width of 60μm and an average aspect ratio of 2.0. The equiaxed grain area on the surface of the steel plate accounts for 22% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0111] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 2.0%. The pickling temperature was 55°C. The temperature of the steel plate during the first cold rolling process was 90°C. The thickness of the steel plate after cold rolling was 0.50 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1, and no edge cracking occurred.

[0112] Example 9

[0113] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0114] (1) The chemical composition of the continuous casting billet is Si: 3.65%, Mn: 0.40%, Al: 0.90%, C: 0.0010%, S: 0.0011%, N: 0.0010%, O: 0.0006%, Sb: 0.08%, and the balance is Fe and unavoidable impurities. The thickness is 120 mm. The continuous casting billet is heated to 1090°C and kept in the furnace for 95 minutes. After being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolling is performed. The starting rolling temperature is 1025°C and the final rolling temperature is 975°C to obtain an intermediate billet with a thickness of 21 mm.

[0115] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then to finish rolling, with the starting rolling temperature at 925°C and the final rolling temperature at 810°C to obtain a 2.8 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 540°C by laminar water and then coiled to obtain a hot-rolled coil.

[0116] The surface of the hot-rolled coil steel plate is composed of fine equiaxed grains with an average grain size of 23μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 15% of the entire steel plate thickness.

[0117] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 35°C / h, the temperature in the soaking section is 680°C, the soaking time is 20h, the cooling rate in the cooling section is 38°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0118] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 40 μm, and the interior of the steel plate is flat recrystallized grains with an average width of 72 μm and an average aspect ratio of 6. The equiaxed grain area on the surface of the steel plate accounts for 33% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0119] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 2.0%. The pickling temperature was 80°C. The temperature of the steel plate during the first cold rolling process was 100°C. The thickness of the steel plate after cold rolling was 0.50 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1, and no edge cracking occurred.

[0120] Comparative Example 1

[0121] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0122] (1) The chemical composition of the continuous casting billet is Si: 3.2%, Mn: 0.20%, Al: 0.25%, C: 0.0020%, S: 0.0015%, N: 0.0008%, O: 0.0005%, Sn: 0.06%, and the balance is Fe and unavoidable impurities, with a thickness of 230 mm. The continuous casting billet is heated to 1120°C, kept in the furnace for 200 min, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, with the starting rolling temperature of 1080°C and the final rolling temperature of 991°C, to obtain an intermediate billet with a thickness of 20 mm.

[0123] (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale with high-pressure water. The starting rolling temperature is 952°C and the final rolling temperature is 860°C to obtain a 2.4 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 590°C with laminar water and coiled to obtain a hot-rolled coil.

[0124] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 27μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 20% of the entire thickness of the steel plate. Figure 7 .

[0125] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 38°C / h, the temperature in the soaking section is 705°C, the soaking time is 30h, the cooling rate in the cooling section is 40°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0126] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 55μm. The interior of the steel plate is flat recrystallized grains with an average width of 80μm and an average aspect ratio of 1.5. The equiaxed grain area on the surface of the steel plate accounts for 50% of the entire thickness of the steel plate. See the metallographic structure of the longitudinal section of the hot-rolled annealed plate for details. Figure 8 The impact work of hot rolled annealed sheet is shown in Table 1.

[0127] (4) The hot-rolled annealed coil is pickled and cold-rolled in the pickling cold rolling mill. The pickling solution is a hydrochloric acid aqueous solution with a mass concentration of 1%. The pickling temperature is 50°C. The temperature of the steel plate during the first cold rolling process is 70°C. The thickness of the steel plate after cold rolling is 0.50 mm. The appearance of the edge of the cold-rolled plate is shown in the following figure. Fig. 9 , edge cracks occur.

[0128] Comparative Example 2

[0129] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0130] (1) The chemical composition of the continuous casting billet is Si: 4.10%, Mn: 0.50%, Al: 0.65%, C: 0.0020%, S: 0.0020%, N: 0.0010%, O: 0.0006%, Sb: 0.10%, and the balance is Fe and unavoidable impurities, with a thickness of 230 mm. The continuous casting billet is heated to 1150°C, kept in the furnace for 80 minutes, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, with the starting rolling temperature of 1100°C and the final rolling temperature of 1010°C, to obtain an intermediate billet with a thickness of 30 mm.

[0131] (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale with high-pressure water, with the starting rolling temperature at 970°C and the final rolling temperature at 885°C, to obtain a 2.6 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 650°C with laminar water and coiled to obtain a hot-rolled coil.

[0132] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 30μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 22% of the entire steel plate thickness.

[0133] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 30°C / h, the temperature T in the soaking section is 730°C, the soaking time is 20h, the cooling rate in the cooling section is 20°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0134] The surface and interior of the hot-rolled annealed coil are all equiaxed recrystallized grains, no flat recrystallized grains are formed, and the average grain size is 87μm. Fig.10 The impact work of hot rolled annealed sheets is shown in Table 1.

[0135] (4) The hot-rolled annealed coil is pickled and cold-rolled in the pickling cold rolling mill. The pickling solution is a hydrochloric acid aqueous solution with a mass concentration of 2%. The pickling temperature is 65°C. The temperature of the steel plate during the first cold rolling process is 90°C. The thickness of the steel plate after cold rolling is 0.35 mm. The appearance of the edge of the cold-rolled plate is shown in the following figure. Fig.11 , edge cracks occur.

[0136] Comparative Example 3

[0137] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0138] (1) The chemical composition of the continuous casting billet is Si: 4.10%, Mn: 0.50%, Al: 1.20%, C: 0.0018%, S: 0.0010%, N: 0.0012%, O: 0.0008%, Sn: 0.06%, Sb: 0.08%, the balance is Fe and unavoidable impurities, and the thickness is 230 mm. The continuous casting billet is heated to 1150°C, kept in the furnace for 80 minutes, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1100°C, and the final rolling temperature is 1010°C, to obtain an intermediate billet with a thickness of 30 mm.

[0139] (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale with high-pressure water, with the starting rolling temperature at 970°C and the final rolling temperature at 885°C, to obtain a 2.6 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 650°C with laminar water and coiled to obtain a hot-rolled coil.

[0140] The surface of the hot-rolled coil steel plate is fine equiaxed grains with an average grain size of 15μm. The interior of the steel plate is severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 10% of the entire steel plate thickness.

[0141] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing. The heating rate in the heating section is 30°C / h, the temperature in the soaking section is 600°C, the soaking time is 15h, the cooling rate in the cooling section is 20°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0142] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 22 μm. The interior of the steel plate is fibrous deformation grains, and no flat recrystallized grains are formed. The impact energy of the hot-rolled annealed coil is shown in Table 1.

[0143] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 1.5%. The pickling temperature was 65°C. The temperature of the steel plate during the first cold rolling process was 85°C. The thickness of the steel plate after cold rolling was 0.20 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1. Edge cracking occurred.

[0144] Comparative Example 4

[0145] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0146] (1) The chemical composition of the continuous casting billet is Si: 3.75%, Mn: 0.50%, Al: 1.50%, C: 0.0024%, S: 0.0025%, N: 0.0015%, O: 0.0004%, Sn: 0.10%, and the balance is Fe and inevitable impurities, with a thickness of 230 mm. The continuous casting billet is heated to 1100°C, kept in the furnace for 150 minutes, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, with the starting rolling temperature of 1070°C and the final rolling temperature of 980°C, to obtain an intermediate billet with a thickness of 30 mm.

[0147] (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale with high-pressure water, with the starting rolling temperature of 950°C and the final rolling temperature of 850°C to obtain a 2.6 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 600°C with laminar water and coiled to obtain a hot-rolled coil.

[0148] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 16μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 4% of the entire steel plate thickness.

[0149] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 30°C / h, the temperature in the soaking section is 600°C, the soaking time is 47h, the cooling rate in the cooling section is 20°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0150] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 40 μm. No flat recrystallized grains are formed inside the steel plate, and the fibrous unrecrystallized grains inside the steel plate account for 60% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0151] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 1.7%. The pickling temperature was 65°C. The temperature of the steel plate during the first cold rolling process was 90°C. The thickness of the steel plate after cold rolling was 0.30 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1. Edge cracking occurred.

[0152] Comparative Example 5

[0153] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0154] (1) The chemical composition of the continuous casting billet is Si: 3.45%, Mn: 0.20%, Al: 0.55%, C: 0.0019%, S: 0.0015%, N: 0.0015%, O: 0.0005%, Sn: 0.12%, and the balance is Fe and unavoidable impurities, with a thickness of 230 mm. The continuous casting billet is heated to 1100°C, kept in the furnace for 135 min, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, with the starting rolling temperature of 1055°C and the final rolling temperature of 974°C, to obtain an intermediate billet with a thickness of 26 mm.

[0155] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then finish rolling is performed. The starting rolling temperature is 940°C and the final rolling temperature is 860°C to obtain a 2.4 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 580°C by laminar water and then coiled to obtain a hot-rolled coil.

[0156] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 25μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 23% of the entire steel plate thickness.

[0157] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 25°C / h, the temperature in the soaking section is 680°C, the soaking time is 25h, the cooling rate in the cooling section is 40°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0158] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 55 μm, and the interior of the steel plate is flat recrystallized grains with an average width of 110 μm and an average aspect ratio of 2. The equiaxed grain area on the surface of the steel plate accounts for 50% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0159] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill in sequence. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 2.0%, the pickling temperature was 85°C, and the temperature of the steel plate during the first cold rolling process was 100°C. The thickness of the steel plate after cold rolling was 0.50 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1, and edge cracking occurred.

[0160] Comparative Example 6

[0161] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0162] (1) The chemical composition of the continuous casting billet is Si: 3.90%, Mn: 0.35%, Al: 1.42%, C: 0.0022%, S: 0.0025%, N: 0.0011%, O: 0.0004%, Sb: 0.15%, the balance is Fe and inevitable impurities, and the thickness is 170 mm. The continuous casting billet is heated to 1130°C, kept in the furnace for 155 min, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, the starting rolling temperature is 1090°C, and the final rolling temperature is 985°C, to obtain an intermediate billet with a thickness of 29 mm.

[0163] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then to finish rolling. The starting rolling temperature is 943°C and the final rolling temperature is 855°C to obtain a 2.8 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 620°C by laminar water and then coiled to obtain a hot-rolled coil.

[0164] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 32μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 21% of the entire steel plate thickness.

[0165] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 18°C / h, the temperature in the soaking section is 750°C, the soaking time is 50h, the cooling rate in the cooling section is 20°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0166] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 70 μm, and the interior of the steel plate is coarse equiaxed recrystallized grains with an average grain size of 110 μm. The impact energy of the hot-rolled annealed coil is shown in Table 1.

[0167] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 1.8%. The pickling temperature was 85°C. The temperature of the steel plate during the first cold rolling process was 96°C. The thickness of the steel plate after cold rolling was 0.35 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1. Edge cracking occurred.

[0168] Comparative Example 7

[0169] A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, specifically comprising the following steps:

[0170] (1) The chemical composition of the continuous casting billet is Si: 3.31%, Mn: 0.55%, Al: 0.75%, C: 0.0015%, S: 0.0010%, N: 0.0013%, O: 0.0008%, Sn: 0.02%, and the balance is Fe and unavoidable impurities, with a thickness of 230 mm. The continuous casting billet is heated to 1090°C, kept in the furnace for 100 min, and after being taken out of the furnace, the surface oxide scale is removed by high-pressure water and then rough rolled, with the starting rolling temperature of 1060°C and the final rolling temperature of 965°C, to obtain an intermediate billet with a thickness of 28 mm.

[0171] (2) The intermediate billet is subjected to high-pressure water to remove the surface iron oxide scale and then to finish rolling. The starting rolling temperature is 920°C and the final rolling temperature is 820°C to obtain a 2.75 mm thick hot-rolled plate. The hot-rolled plate is then cooled to 590°C by laminar water and then coiled to obtain a hot-rolled coil.

[0172] The surface of the hot-rolled coil is composed of fine equiaxed grains with an average grain size of 23μm. The interior of the steel plate is composed of severely elongated fibrous deformed grains. The equiaxed grain area on the surface of the steel plate accounts for 3% of the entire steel plate thickness.

[0173] (3) The hot-rolled coil is placed in a bell-type annealing furnace for annealing treatment. The heating rate in the heating section is 20°C / h, the temperature in the soaking section is 660°C, the soaking time is 15h, the cooling rate in the cooling section is 34°C / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, it is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil.

[0174] The surface of the hot-rolled annealed coil is equiaxed grains with an average grain size of 34μm, and the interior of the steel plate is flat recrystallized grains with an average width of 91μm and an average aspect ratio of 1.6. The equiaxed grain area on the surface of the steel plate accounts for 26% of the entire thickness of the steel plate. The impact energy of the hot-rolled annealed plate is shown in Table 1.

[0175] (4) The hot-rolled annealed coil was pickled and cold-rolled in the pickling cold rolling mill in sequence. The pickling solution was a hydrochloric acid aqueous solution with a mass concentration of 2%. The pickling temperature was 50°C. The temperature of the steel plate during the first cold rolling process was 80°C. The thickness of the steel plate after cold rolling was 0.50 mm. The cracking of the edge of the cold-rolled plate is shown in Table 1. Edge cracking occurred.

[0176] It can be seen from the comparative example that when the preparation process is not within the design scope of the present invention, the impact energy of the hot-rolled annealed sheet is very low, the toughness and plasticity of the steel sheet are very poor, and edge cracking occurs during the cold rolling process. The impact energy of the hot-rolled annealed sheet in the embodiment of the present invention is significantly better than that of the comparative example, and no edge cracking occurs during the cold rolling process.

[0177] Table 1 Impact energy and cold rolling edge cracking of hot rolled annealed sheets in the embodiments and comparative examples

[0178]

Claims

1. A method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel, characterized in that: The specific steps include: (1) heating a continuous casting billet having a silicon content of not less than 3.2% by mass and a thickness of 70 to 240 mm to 1060 to 1100° C., keeping the billet in a furnace for 90 to 180 minutes, removing the surface iron oxide scale with high-pressure water after the billet is taken out of the furnace, and then performing rough rolling, with the starting rolling temperature of 1020 to 1070° C. and the final rolling temperature of 930 to 980° C., to obtain an intermediate billet having a thickness of 20 to 30 mm; (2) The intermediate billet is subjected to finish rolling after removing the surface iron oxide scale by high-pressure water, with the starting rolling temperature of 890-940° C. and the final rolling temperature of 790-840° C. to obtain a hot-rolled plate with a thickness of 2.4-2.8 mm, and then the hot-rolled plate is cooled to 500-570° C. by laminar water and then coiled to obtain a hot-rolled coil; (3) placing the hot-rolled coil into a bell-type annealing furnace for annealing, wherein the heating rate in the heating section is 20 to 35° C. / h, the temperature T in the soaking section is 620 to 690° C., the soaking time t satisfies t=15+(690-T)×(0.3 to 0.5)h, the cooling rate in the cooling section is 15 to 40° C. / h, the atmosphere in the furnace is hydrogen, and after cooling to room temperature, the coil is taken out from the bell-type annealing furnace to obtain a hot-rolled annealed coil; (4) After the hot-rolled annealed coil is uncoiled, it is pickled and cold-rolled in a pickling cold rolling mill to obtain a cold-rolled steel plate with a thickness of 0.20 to 0.50 mm.

2. The method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel according to claim 1, characterized in that: In the step (1), the chemical composition of the continuous casting billet is as follows by weight percentage: Si: 3.2-4.1%, Mn: 0.20-0.55%, Al: 0.2-1.5%, C≤0.0027%, S≤0.0025%, N≤0.0020%, O≤0.0010%, Sn or Sb or Sn+Sb≤0.15%, and the remainder is Fe and unavoidable impurities.

3. The method for improving the cold rolling processability of high silicon non-oriented silicon steel according to claim 1, characterized in that: In step (2), the surface layer of the hot-rolled coil is fine equiaxed grains with an average grain size of 10 to 25 μm, the interior of the steel plate is severely elongated fibrous deformed grains, and the equiaxed grain area on the surface of the steel plate accounts for 5 to 18% of the entire steel plate thickness.

4. The method for improving the cold rolling processing performance of high-silicon non-oriented silicon steel according to claim 1, characterized in that: In the step (3), the surface layer of the steel plate of the obtained hot-rolled annealed coil is equiaxed grains with an average grain size of 30 to 50 μm.

5. The method for improving the cold rolling processability of high silicon non-oriented silicon steel according to claim 1, characterized in that: In the step (3), the interior of the steel plate of the obtained hot-rolled annealed coil is flat recrystallized grains, the average width of the flat recrystallized grains is 35 to 75 μm, and the average aspect ratio of the flat recrystallized grains is 2 to 6.

6. The method for improving the cold rolling processability of high silicon non-oriented silicon steel according to claim 1, characterized in that: In the step (3), the equiaxed grain area on the surface of the steel plate of the obtained hot-rolled annealed coil accounts for 20 to 55% of the entire steel plate thickness.

7. The method for improving the cold rolling processability of high silicon non-oriented silicon steel according to claim 1, characterized in that: In the step (4), the pickling solution is a hydrochloric acid aqueous solution with a mass concentration of 1 to 2%, and the pickling temperature is 50 to 85°C.

8. The method for improving the cold rolling processability of high silicon non-oriented silicon steel according to claim 1, characterized in that: In the step (4), the pickled plate needs to be preheated to 70-100° C. before the first cold rolling in the cold rolling process.

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