Method for improving soft magnetic properties of cast-rolled oriented gradient high silicon steel clad plate

Abstract

The application discloses a method for improving the soft magnetic property of a cast-rolled oriented gradient high-silicon steel composite plate, wherein the core layer material of the high-silicon steel composite plate is high-silicon steel, and the high-silicon steel is coated and cast with common silicon steel and then subjected to solid-liquid casting and rolling. After the hot-rolled plate is pickled, six-pass step-by-step cooling warm rolling is adopted, and a new type of oriented gradient high-silicon steel composite plate is prepared by combining a new technology of asynchronous warm rolling and cross rolling. Deep cryogenic treatment can inhibit the formation of D03 and B2 ordered phases and reduce the ordered phase content, thereby providing a possibility for solving the problems of complex ordered structure and difficult deformation of high-silicon steel. Diffusion annealing heat treatment is conducted on the composite plate, and argon is introduced for protection, so that the high-silicon steel composite plate with different silicon contents in gradient distribution is prepared; and laser marking technology is adopted to improve the soft magnetic property of the composite plate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metal soft magnetic material preparation and processing, in particular to a method for improving the soft magnetic properties of cast-rolled oriented gradient high-silicon steel composite plate. BACKGROUND

[0002] High-silicon steel, also known as high-silicon electrical steel, refers to a silicon-iron alloy with a silicon content of 4.5-7wt%, which exhibits excellent soft magnetic properties such as high magnetic permeability, low coercivity, low iron loss, and nearly zero magnetostriction coefficient, and has wide application prospects in the high-frequency field. The invalid electric energy consumed due to the obstruction of magnetic flux change is called core loss (iron loss), which is an important indicator for measuring the magnetic properties of silicon steel. Currently, the silicon content in silicon steel sheets produced at home and abroad is mostly controlled within 4%. When the silicon content in steel reaches 6.5%, the magnetostriction coefficient is almost zero, the invalid electric energy consumed by the operation of the equipment is significantly reduced, and the magnetic permeability is significantly improved, which has superior soft magnetic properties that ordinary silicon steel cannot match.

[0003] The solid-liquid casting and rolling composite process enables simultaneous solidification and deformation of the metal, has high composite strength, and can achieve efficient continuous near-net forming of bimetallic composite plate. Compared with traditional thin strip production processes, due to the high cooling intensity, fast cooling speed of the casting blank, small size of non-metallic inclusions, broken coarse primary dendrites, reduced element segregation, and more fine equiaxed grains, the composite plate produced by the casting and rolling composite method can realize the gradient distribution of silicon content in high-silicon steel at high temperature, which is an ideal method for producing high-silicon steel soft magnetic alloy composite plate. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a method for improving the soft magnetic properties of cast-rolled oriented gradient high-silicon steel composite plate, which uses a new technology of asynchronous warm rolling combined with deep cold rolling to prepare a new type of oriented gradient high-silicon steel composite plate. Through laser scoring technology, the soft magnetic properties of the product surface are improved, and a high-silicon steel sheet with a gradient distribution of silicon content is prepared.

[0005] To this end, the present application provides the following technical solutions:

[0006] The present application provides a method for improving the soft magnetic properties of cast-rolled oriented gradient high-silicon steel composite plate, which includes the steps of preparing the core material, casting and rolling, hot rolling, first pickling, warm rolling, second pickling, deep cold rolling, diffusion annealing, and laser scoring, wherein:

[0007] The warm rolling comprises: warm rolling the pickled hot-rolled composite plate on a four-roll cold rolling mill, a total of six passes; the first pass adopts asynchronous warm rolling; the second pass adopts cross warm rolling; the third pass adopts asynchronous warm rolling; the fourth pass adopts cross warm rolling; the last two passes adopt synchronous warm rolling; after each pass, the rolled piece is quickly put back into the heating furnace and kept for a preset time;

[0008] The cryogenic rolling comprises: before the cryogenic rolling, the rolls are opened, the zero-load wheel is turned, the upper and lower work rolls of the rolling mill are cooled by the nitrogen cooling spray gun of the rolling mill, and the surface temperature of the rolls is-180 to-140℃; before each pass of rolling, the rolled plate is placed in a cryogenic tank filled with liquid nitrogen, and after the rolled plate is cooled in the liquid nitrogen, it is quickly taken out for cryogenic rolling;

[0009] The laser marking comprises: using a laser marking device to simultaneously mark the upper and lower surfaces of the composite plate with a highly focused continuous wave laser beam to prepare a high-silicon steel composite plate with a gradient distribution of silicon content.

[0010] Further, in the warm rolling, in the first pass, the rolled plate is heated to 700-750℃, the rolling force is 180-200kN, the pass reduction rate is 10%-12%, the asynchronous warm rolling is to 1.35-1.76mm, the asynchronous speed ratio is 1.05-1.15, the lower roll is a slow roll, the roll speed is always kept constant, the upper roll is a fast roll, the upper roll speed is adjusted according to the asynchronous speed ratio, the lower roll speed is 0.2-0.4m / s, and the upper roll speed is 0.21-0.46m / s;

[0011] In the second pass, the rolled plate is heated to 630-680℃ and rotated by 90° for cross rolling, the pass reduction rate is 6%-8%, the synchronous warm rolling is to 1.27-1.62mm, and the rolling force is 140-160kN;

[0012] In the third pass, the rolled plate is rotated by 90° to the length direction, heated to 550-600℃, the rolling force is 100-120kN, the pass reduction rate is 8%-10%, the asynchronous warm rolling is to 1.17-1.46mm, the asynchronous speed ratio is 1.2-1.3, the lower roll is a slow roll, the roll speed is always kept constant, the upper roll is a fast roll, the lower roll speed is 0.2-0.4m / s, and the upper roll speed is 0.24-0.52m / s;

[0013] In the fourth pass, the rolled plate is heated to 480-530℃ and rotated by 90° for cross rolling, the pass reduction rate is 5%-7%, the synchronous warm rolling is to 1.11-1.38mm, and the rolling force is 70-90kN;

[0014] Finally, the plate is rotated 90° to the length direction, and is synchronously warm-rolled at 400-450℃, with a reduction of 8-10% per pass, a rolling force of 140-160kN, and a thickness of 0.94-1.12mm.

[0015] Further, the core layer material has a chemical composition by weight percentage of C 0.005-0.01%, Si 6.5-6.9%, Al 0.4-0.8%, Mn 0.1-0.16%, Cu 0.3-0.5%, Ta 0.5-0.9%, N 0.015-0.025%, P <0.01%, S <0.01%, O <0.003%, and the balance of Fe.

[0016] The preparation of the core layer material includes: smelting the core layer material in a medium-frequency vacuum induction heating furnace at a smelting temperature of 1540-1570℃, and then air-forging the core layer material into a square billet with a thickness of 30-45mm at 1150-1200℃; after holding at 1150-1200℃ for 40-60min, the core layer material is hot-rolled without lubrication on a hot rolling mill and is rolled to a thickness of 5-7mm in 6-8 passes, with a rough rolling temperature of 1100-1150℃ and a final rolling temperature of 860-880℃.

[0017] Further, the hot rolling includes: hot rolling the composite plate billet obtained by casting and rolling in combination, with a heating temperature of 1130-1150℃ and a holding time of 20-40min; hot-rolling the composite plate billet without lubrication on a two-high reversible experimental hot rolling mill and rolling to a thickness of 1.5-2mm in 3-5 passes, with a rough rolling temperature of 1100-1120℃ and a final rolling temperature of 850-870℃, and then air-cooling to room temperature.

[0018] Further, the first acid pickling includes: pickling the hot-rolled plate after hot rolling with a 6%-8% concentration hydrochloric acid solution, at an acid pickling temperature of 50-60℃ and for an acid pickling time of 15-25min, to remove the surface iron oxide scale.

[0019] Further, the second acid pickling includes: pickling the warm-rolled plate with a 6%-8% concentration hydrochloric acid solution, at an acid pickling temperature of 50-60℃ and for an acid pickling time of 15-25min, to remove the surface iron oxide scale.

[0020] Further, the continuous annealing includes: continuously annealing the composite plate obtained by cryogenic asynchronous rolling in a heating furnace, adopting a three-stage step-by-step annealing process, first heating to 600-700℃ at a rate of 4℃ / s and holding for 2-4min, then heating to 850-950℃ at a rate of 5℃ / s and holding for 2-4min, and finally heating to 1000-1100℃ at a rate of 6℃ / s, with a holding time of 3-5min for the thin plate, and then air-cooling to room temperature while nitrogen is introduced to prevent oxidation.

[0021] Further, the laser scoring has a scoring line spacing of 3-5 mm, a laser power of 2000-2500 W, and a scanning speed of 250-350 m / min.

[0022] Further, the casting-rolling compounding comprises: cutting the obtained core layer hot-rolled plate into a rectangular strip of a predetermined size, and placing the rectangular strip into a casting mold to be in a suspended state supported by a 3wt% Si silicon steel gasket; carrying out cladding casting in a vacuum electromagnetic induction heating furnace, pouring liquid cladding metal at a target temperature of 1560-1580℃, and carrying out solid-liquid casting-rolling compounding in a casting-rolling compounding device, and carrying out flat-rolling compounding in a hot-rolling compounding device, and casting-rolling to 3-5 mm.

[0023] Further, the cryogenic rolling comprises: cryogenic rolling for 5 passes, wherein the roller speed is 0.1-0.15 m / s, the pass reduction rate of the first and last two passes is 10%-12%, and the rolling force is 160-180 kN; the pass reduction rate of the middle three passes is 14%-16%, and the rolling force is 200-220 kN, and the rolling is to 0.48-0.52 mm.

[0024] The application has the advantages and positive effects that: the application is directed to the improvement of the soft magnetic performance of the oriented gradient high-silicon steel composite plate prepared by the casting-rolling compounding technology, the asynchronous combined warm rolling process is adopted, the friction force opposite to the direction of the shearing stress is formed in the rolling area, the texture strength difference between the fast roller side and the slow roller side is formed, the texture strength of the λ fiber beneficial to the magnetic induction intensity is improved, the problems of large deformation resistance and difficult deformation of the high-silicon steel are solved, the texture type is improved, and the magnetic induction intensity is improved; the asynchronous rolling technology cannot well control the reduction and the force of the plate edge, the thickness change amount of the rolling piece edge is inconsistent with the thickness change amount of the middle, and the plate warping is generated, and the cross rolling method can well solve the problem. The continuous annealing method can make the recrystallized grains obviously coarsen with the continuous annealing heating, but does not affect the grain orientation, so that the high-frequency iron loss is reduced without reducing the magnetism. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0026] Figure 1 The B2 ordered phase transmission electron microscope photos of the core of the composite plates after warm rolling of the embodiments 1-3 are shown in (a) embodiment 1, (b) embodiment 2, and (c) embodiment 3.

[0027] Figure 2 The test graphs of the magnetic induction intensity and the iron loss hysteresis loop of the finished product of Example 1 and Example 3 of the present application are as follows: (a) B8 of Example 1 (measured at a magnetic field intensity of 800 A / m -1 10 / 50 (1T and 50Hz) ; (c) B8 of Example 3; (d) P 10 / 50 . DETAILED DESCRIPTION

[0028] In order to make the person skilled in the art better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by the person skilled in the art without creative labor should belong to the protection scope of the present application.

[0029] It should be noted that the terms "first", "second" and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in other than the order illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0030] Example 1

[0031] The method for improving the soft magnetic properties of the cast-rolled oriented gradient high-silicon steel composite plate in the present embodiment comprises the following steps:

[0032] S11, preparation of the core layer material:

[0033] The chemical composition of the core layer material is as follows in terms of percentage by weight: C 0.01%, Si 6.9%, Al 0.8%, Mn 0.16%, Cu 0.5%, Ta 0.9%, N 0.025%, P 0.003%, S 0.003%, O 0.001%, and the balance of Fe;

[0034] ​The smelting of the core layer material is performed in a medium frequency vacuum induction heating furnace, the smelting temperature is 1570℃, and then the air free forging is pressed at 1200℃ to form a square billet with a thickness of 30mm. After being kept at 1200℃ for 40min, the hot rolling is performed on a hot rolling mill without lubrication and is rolled to 5mm through 6 passes, the open rolling temperature is 1100℃, and the final rolling temperature is 860℃;

[0035] S12, casting-rolling compounding: the core layer hot-rolled plate obtained in S11 is cut into a rectangular strip with a certain size and is placed in a casting mold in a suspended state supported by a 3wt% Si silicon steel gasket. The cladding casting is performed in a vacuum electromagnetic induction heating furnace, the liquid cladding metal (3wt% Si silicon steel) is poured at a target temperature of 1580℃, and the solid-liquid casting-rolling compounding is performed on a casting-rolling compounding device, the flat rolling compounding is performed on a hot rolling compounding device, and the casting-rolling is performed to 3mm;

[0036] S13, hot rolling: the hot rolling is performed on the compounding billet in S12, the heating temperature is 1150℃, the temperature is kept for 20min, then the hot rolling is performed on a two-high reversible experimental hot rolling mill without lubrication and is rolled to 1.5mm through 3 passes, the open rolling temperature is 1100℃, the final rolling temperature is 850℃, and then the air cooling is performed to room temperature;

[0037] S14, first pickling: the hot-rolled plate is pickled by using a 6% concentration hydrochloric acid solution, the pickling temperature is 60℃, the pickling time is 25min, and the surface iron oxide scale is removed;

[0038] S15, warm rolling: the hot-rolled composite plate after pickling is subjected to warm rolling on a four-roll cold rolling mill, a total of six passes of warm rolling. The first pass adopts asynchronous warm rolling, the rolling plate is heated to 700℃, the rolling force is 180kN, the pass reduction rate is 10%, the asynchronous warm rolling is to 1.35mm, the asynchronous ratio is 1.05, the lower roller is the slow roller, the roller speed is always kept constant, the upper roller is the fast roller, the roller speed of the upper roller is adjusted according to the asynchronous ratio, the roller speed of the lower roller is 0.2m / s, and the roller speed of the upper roller is 0.21m / s; the second pass adopts cross warm rolling, the rolling plate is heated to 630℃ and then rotated by 90° for transverse rolling, the pass reduction rate is 6%, the synchronous warm rolling is to 1.27mm, and the rolling force is 140kN; the third pass rotates the rolling plate by 90° to the length direction, heats it to 550℃, the rolling force is 100kN, the pass reduction rate is 8%, the asynchronous warm rolling is to 1.17mm, the asynchronous ratio is 1.2, the lower roller is the slow roller, the roller speed is always kept constant, the upper roller is the fast roller, the roller speed of the lower roller is 0.2m / s, and the roller speed of the upper roller is 0.24m / s; the fourth pass adopts cross warm rolling, the rolling plate is heated to 480℃ and then rotated by 90° for transverse rolling, the pass reduction rate is 5%, the synchronous warm rolling is to 1.11mm, and the rolling force is 70kN; the last two passes rotate the rolling plate by 90° to the length direction, and the synchronous warm rolling is carried out at 400℃, the pass reduction rate is 8% each time, the rolling force is 140kN, and the warm rolling is to 0.94mm; after each pass, the rolling piece is quickly put back into the heating furnace and kept for 1min;

[0039] S16, second pickling: the hot-rolled plate is pickled with 6% concentration hydrochloric acid solution, the pickling temperature is 60℃, the pickling time is 25min, and the surface iron oxide scale is removed;

[0040] S17, cryogenic rolling: before cryogenic rolling, the roller is started, the zero load wheel is turned, the upper and lower working rollers of the rolling mill are cooled by using the nitrogen cooling spray gun of the rolling mill, and the roller surface temperature is-180℃; before each pass of rolling, the rolling plate needs to be cooled in the cryogenic tank filled with liquid nitrogen for 2min, so that the temperature of the multi-layer plate blank is-180℃, after the rolling plate is cooled in the liquid nitrogen, it is quickly taken out for cryogenic rolling. The cryogenic rolling is carried out for 5 passes, the roller speed of the rolling mill is 0.1m / s, the pass reduction rate of the first and last two passes is 10%, and the rolling force is 160kN; the pass reduction rate of the middle three passes is 14%, the rolling force is 200kN, and the rolling is to 0.48mm;

[0041] S18, continuous annealing: the composite plate obtained in S17 is subjected to continuous annealing heat treatment in a heating furnace, a three-stage step-by-step annealing process is adopted, first heated to 600℃ at a rate of 4℃ / s, the holding time is 4min, then heated to 850℃ at a rate of 5℃ / s, the holding time is 4min, finally heated to 1000℃ at a rate of 6℃ / s, the holding time of the thin plate is 5min, nitrogen is introduced to prevent oxidation, and then air cooled to room temperature;

[0042] S19, laser marking: using a laser marking device, a highly focused continuous wave laser beam is simultaneously marked on the upper and lower surfaces of the composite plate, the marking line spacing is 5 mm, the laser power is 2500 W, and the scanning speed is 250 m / min.

[0043] Example 2

[0044] The method for improving the soft magnetic properties of the cast-rolled oriented gradient high-silicon steel composite plate in this embodiment includes the following steps:

[0045] S21, preparation of core layer material:

[0046] The chemical composition of the core layer material is as follows in terms of weight percentage: C 0.008%, Si 6.7%, Al 0.6%, Mn 0.13%, Cu 0.4%, Ta 0.7%, N 0.02%, P 0.003%, S 0.003%, O 0.001%, and the balance Fe;

[0047] The smelting of the core layer material is carried out in a medium-frequency vacuum induction heating furnace, and the smelting temperature is 1550℃. Then, the air free forging is pressed into a 38mm thick square billet at 1180℃. After holding at 1180℃ for 50min, the hot rolling is carried out on a hot rolling mill and is hot rolled to 6mm in 7 passes, the rolling temperature is 1100-1120℃, and the final rolling temperature is 870℃;

[0048] S22, cast-rolling: the core layer hot-rolled plate obtained in S21 is cut into a rectangular strip of a certain size and placed in a casting mold supported by a 3wt% Si silicon steel gasket in a suspended state. The cladding casting is carried out in a vacuum electromagnetic induction heating furnace, and the liquid cladding metal (3wt% Si silicon steel) is poured at a target temperature of 1570℃. The solid-liquid cast-rolling is carried out on the cast-rolling device, and the flat rolling is carried out on the hot rolling device. The cast-rolling is carried out to 4mm;

[0049] S23, hot rolling: the composite plate blank in S22 is hot rolled at a heating temperature of 1140℃ and holding for 30min, then the hot rolling is carried out on a two-high reversible experimental hot rolling mill without lubrication and is hot rolled to 1.8mm in 4 passes, the rolling temperature is 1110℃, the final rolling temperature is 860℃, and then air cooling is carried out to room temperature;

[0050] S24, first pickling: the hot-rolled plate is pickled using a 7% concentration hydrochloric acid solution, the pickling temperature is 55℃, the pickling time is 20min, and the surface iron oxide scale is removed;

[0051] S25, warm rolling: the hot-rolled composite plate after pickling is subjected to warm rolling on a four-roll cold rolling mill, a total of six passes of warm rolling. The first pass adopts asynchronous warm rolling, the rolling plate is heated to 720℃, the rolling force is 190kN, the pass reduction rate is 11%, the asynchronous warm rolling is to 1.6mm, the asynchronous ratio is 1.1, the lower roller is the slow roller, the roller speed is always kept constant, the upper roller is the fast roller, the roller speed of the upper roller is adjusted according to the asynchronous ratio, the roller speed of the lower roller is 0.3m / s, and the roller speed of the upper roller is 0.33m / s; the second pass adopts cross warm rolling, the rolling plate is heated to 660℃ and then rotated by 90° for transverse rolling, the pass reduction rate is 7%, the synchronous warm rolling is to 1.49mm, and the rolling force is 150kN; the third pass rotates the rolling plate by 90° to the length direction, heats it to 570℃, the rolling force is 110kN, the pass reduction rate is 9%, the asynchronous warm rolling is to 1.36mm, the asynchronous ratio is 1.25, the lower roller is the slow roller, the roller speed is always kept constant, the upper roller is the fast roller, the roller speed of the lower roller is 0.3m / s, and the roller speed of the upper roller is 0.38m / s; the fourth pass adopts cross warm rolling, the rolling plate is heated to 500℃ and then rotated by 90° for transverse rolling, the pass reduction rate is 6%, the synchronous warm rolling is to 1.28mm, and the rolling force is 80kN; the last two passes rotate the rolling plate by 90° to the length direction, and the synchronous warm rolling is carried out at 430℃, the pass reduction rate is 9% each time, the rolling force is 150kN, and the warm rolling is to 1.06mm; after each pass, the rolling piece is quickly put back into the heating furnace and kept for 2min;

[0052] S26, second pickling: the hot-rolled plate is pickled with 7% concentration hydrochloric acid solution, the pickling temperature is 55℃, the pickling time is 20min, and the surface iron oxide scale is removed;

[0053] S27, cryogenic rolling: before cryogenic rolling, the roller is started, the zero load wheel is turned, the upper and lower working rollers of the rolling mill are cooled by using the nitrogen cooling spray gun of the rolling mill, and the roller surface temperature is-160℃; before each pass of rolling, the rolling plate needs to be cooled in the cryogenic tank filled with liquid nitrogen for 3min, so that the temperature of the multi-layer plate blank is-160℃, after the rolling plate is cooled in the liquid nitrogen, it is quickly taken out for cryogenic rolling. The cryogenic rolling is carried out for 5 passes, the roller speed of the rolling mill is 0.13m / s, the pass reduction rate of the first and last two passes is 11%, and the rolling force is 170kN; the pass reduction rate of the middle three passes is 15%, the rolling force is 210kN, and the rolling is to 0.5mm;

[0054] S28, continuous annealing: the composite plate obtained in S27 is subjected to continuous annealing heat treatment in a heating furnace, a three-stage step-by-step annealing process is adopted, first heated to 650℃ at a rate of 4℃ / s, the holding time is 3min, then heated to 900℃ at a rate of 5℃ / s, the holding time is 3min, finally heated to 1050℃ at a rate of 6℃ / s, the holding time of the thin plate is 4min, nitrogen is introduced to prevent oxidation, and then air cooling to room temperature;

[0055] S29, laser marking: using laser marking equipment, a highly focused continuous wave laser beam is simultaneously marked on the upper and lower surfaces of the clad plate, the marking line spacing is 4 mm, the laser power is 2300 W, and the scanning speed is 300 m / min.

[0056] Example 3

[0057] S31, preparation of core layer material:

[0058] The chemical composition of the core layer material is as follows in terms of weight percentage: C 0.005%, Si 6.5%, Al 0.4%, Mn 0.1%, Cu 0.3%, Ta 0.5%, N 0.015%, P 0.003%, S 0.003%, O 0.001%, and the balance Fe;

[0059] The smelting of the core layer material is performed in a medium-frequency vacuum induction heating furnace, and the smelting temperature is 1540°C. Then, the air free forging is pressed into a 45 mm thick square billet at 1150°C. After holding at 1150°C for 60 min, the hot rolling is performed on a non-lubricated hot rolling mill and is hot rolled to 7 mm through 8 passes, the rolling temperature is 1150°C, and the final rolling temperature is 880°C;

[0060] S32, casting and rolling: the core layer hot-rolled plate obtained in S31 is cut into a rectangular strip of a certain size and placed in a casting mold supported by a 3wt% Si silicon steel gasket in a suspended state. The cladding casting is performed in a vacuum electromagnetic induction heating furnace, and the liquid cladding metal (3wt% Si silicon steel) is poured at a target temperature of 1560°C. The solid-liquid casting and rolling are performed on a casting and rolling device, and the flat rolling is performed on a hot rolling device. The casting and rolling are performed to 5 mm;

[0061] S33, hot rolling: the hot rolling is performed on the clad plate billet in S32, the heating temperature is 1130°C, the holding time is 40 min, then the non-lubricated hot rolling is performed on a two-high reversible experimental hot rolling mill and is hot rolled to 2 mm through 5 passes, the rolling temperature is 1120°C, the final rolling temperature is 870°C, and then air cooling is performed to room temperature;

[0062] S34, first pickling: the hot-rolled plate is pickled using an 8% concentration hydrochloric acid solution, the pickling temperature is 50°C, the pickling time is 15 min, and the surface iron oxide scale is removed;

[0063] S35, warm rolling: the hot-rolled composite plate after pickling is subjected to warm rolling on a four-roll cold rolling mill, a total of six passes of warm rolling. The first pass adopts asynchronous warm rolling, the plate is heated to 750℃, the rolling force is 200kN, the pass reduction rate is 12%, the asynchronous warm rolling is to 1.76mm, the asynchronous ratio is 1.15, the lower roller is the slow roller, the roller speed is always kept constant, the upper roller is the fast roller, the roller speed of the upper roller is adjusted according to the asynchronous ratio, the roller speed of the lower roller is 0.4m / s, and the roller speed of the upper roller is 0.46m / s; the second pass adopts cross warm rolling, the plate is heated to 680℃ and then rotated by 90° for transverse rolling, the pass reduction rate is 8%, the synchronous warm rolling is to 1.62mm, and the rolling force is 160kN; the third pass rotates the plate by 90° to the length direction, heats it to 600℃, the rolling force is 120kN, the pass reduction rate is 10%, the asynchronous warm rolling is to 1.46mm, the asynchronous ratio is 1.3, the lower roller is the slow roller, the roller speed is always kept constant, the upper roller is the fast roller, the roller speed of the lower roller is 0.4m / s, and the roller speed of the upper roller is 0.52m / s; the fourth pass adopts cross warm rolling, the plate is heated to 530℃ and then rotated by 90° for transverse rolling, the pass reduction rate is 7%, the synchronous warm rolling is to 1.38mm, and the rolling force is 90kN; the last two passes rotate the plate by 90° to the length direction, and the synchronous warm rolling is carried out at 450℃, the pass reduction rate is 10% each time, the rolling force is 160kN, and the warm rolling is to 1.12mm; after each pass, the rolled piece is quickly put back into the heating furnace and kept for 3min;

[0064] S36, second pickling: the hot-rolled plate is pickled with 8% concentration hydrochloric acid solution, the pickling temperature is 50℃, the pickling time is 15min, and the surface iron oxide scale is removed;

[0065] S37, cryogenic rolling: before cryogenic rolling, the roller is started, the zero load wheel is turned, the upper and lower work rollers of the rolling mill are cooled by using the nitrogen cooling spray gun of the rolling mill, and the roller surface temperature is-140℃; before each pass of rolling, the plate is placed in a cryogenic tank filled with liquid nitrogen and cooled for 4min, so that the temperature of the multi-layer plate blank is-140℃, the plate is cooled in the liquid nitrogen, then taken out quickly and subjected to cryogenic rolling. The cryogenic rolling is carried out for 5 passes, the roller speed of the rolling mill is 0.15m / s, the pass reduction rate of the first and last two passes is 12%, and the rolling force is 180kN; the pass reduction rate of the middle three passes is 16%, the rolling force is 220kN, and the rolling is to 0.52mm;

[0066] S38, continuous annealing: the composite plate obtained in S37 is subjected to continuous annealing heat treatment in a heating furnace, a three-stage step-by-step annealing process is adopted, first heated to 700℃ at a rate of 4℃ / s, the holding time is 2min, then heated to 950℃ at a rate of 5℃ / s, the holding time is 2min, finally heated to 1100℃ at a rate of 6℃ / s, the holding time is 3min, nitrogen is introduced to prevent oxidation, and then air cooled to room temperature;

[0067] S39, laser marking: using laser marking equipment, the highly focused continuous wave laser beam is simultaneously marked on the upper and lower surfaces of the composite plate, the marking line spacing is 3mm, the laser power is 2000W, and the scanning speed is 350m / min.

[0068] As can be seen from the figure, after warm rolling of the composite plate, the relatively complete B2 ordered phase is broken into a large number of small blocky ordered phases, and the order degree is reduced, which together with the dynamic recovery in the rolling process plays a role in softening the matrix.

[0069] In the above three embodiments, for the improvement of the soft magnetic properties of the oriented gradient high-silicon steel composite plate prepared by the cast-rolling composite technology, the asynchronous combined warm rolling process is adopted, the friction force opposite to the direction of the shear stress is formed in the rolling area, the difference in texture strength between the fast roller side and the slow roller side is formed, the texture strength of the λ fiber beneficial to the magnetic induction intensity is improved, the problems such as large deformation resistance and difficult deformation of high-silicon steel are solved, the texture type is improved, and the magnetic induction intensity is improved; the asynchronous rolling technology cannot well control the reduction and force of the edge of the plate, so that the thickness change of the edge of the rolled piece is inconsistent with the thickness change of the middle, and the plate warps, the cross-rolling method can well solve this problem. The continuous annealing method can make the recrystallized grains significantly coarsen with continuous annealing heating, but will not affect the grain orientation, so as to reduce the high-frequency iron loss without reducing the magnetism.

[0070] In the embodiment, a TECNAIG220 transmission electron microscope is used to observe the dark field image of the B2 ordered phase in the warm-rolled high-silicon steel composite plate. In the embodiment, a silicon steel measuring device is used to test the longitudinal magnetic properties of the finished high-silicon steel composite plate. From the Figure 1 As can be seen from the B2 ordered phase transmission electron microscope photos of the center of the composite plate after warm rolling of the embodiments 1-3 shown in the figure, after warm rolling of the composite plate, the relatively complete B2 ordered phase is broken into a large number of small blocky ordered phases, and the order degree is reduced, which together with the dynamic recovery in the rolling process plays a role in softening the matrix. From the Figure 2 The finished products of the embodiments 1 and 3 shown in the figure have a magnetic induction intensity B8 of 800Am -1 The magnetic induction intensity B8 and the iron loss value P measured under the condition of 1T and 50Hz 10 / 50 As can be seen, the magnetic induction intensity B8 value of the embodiment 1 is 1.275T, the iron loss P 10 / 50 value of the embodiment 1 is 1.281W / kg, in contrast, the magnetic induction intensity B8 value of the embodiment 3 is 1.303T, and the iron loss P 10 / 50 value of the embodiment 3 is 0.706W / kg.

[0071] In the step-by-step temperature reduction warm rolling in Example 1, the rolling speed ratio of the first pass is 1.05, and the rolling speed ratio of the third pass is 1.2, while in Example 3, the rolling speed ratio of the first pass is 1.15, and the rolling speed ratio of the third pass is 1.3; with the increase of the rolling speed ratio, the recrystallized grains of the finished sheet are gradually refined, the strength of the λ fiber texture which is beneficial to the magnetic induction intensity is improved, and thus the magnetic induction intensity B8 value is gradually improved. In Example 1, the three-stage step-by-step temperature increasing continuous annealing process is adopted, and the annealing temperature is heated from 600℃ to 1000℃, while in Example 3, the three-stage step-by-step temperature increasing annealing process is also adopted, and the annealing temperature is heated from 700℃ to 1100℃; with the increase of the continuous annealing heating, the recrystallized grains are obviously coarsened, and the grain orientation is not affected, so that the high-frequency iron loss is effectively reduced without reducing the magnetism.

[0072] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for improving the soft magnetic properties of cast-rolled orientation gradient high-silicon steel composite plates, characterized in that, The method includes the following steps: preparation of core material, casting-rolling composite, hot rolling, first pickling, warm rolling, second pickling, cryogenic rolling, diffusion annealing, and laser marking, wherein: The warm rolling process includes: warm rolling the pickled hot-rolled composite plate on a four-roll cold rolling mill for a total of six passes; the first pass is asynchronous warm rolling; the second pass is cross warm rolling; the third pass is asynchronous warm rolling; the fourth pass is cross warm rolling; and the last two passes are synchronous warm rolling; after each pass, the rolled piece is quickly placed back into the heating furnace and held at the temperature for a preset time. The cryogenic rolling process includes: before cryogenic rolling, turning the rolls on and rotating them under zero load, using the mill's nitrogen cooling spray gun to cool the upper and lower work rolls of the mill to achieve a roll surface temperature of -180 to -140°C; before each rolling pass, the rolled plate needs to be placed in a cryogenic chamber containing liquid nitrogen, and after the rolled plate is cooled in liquid nitrogen, it is quickly taken out for cryogenic rolling. The laser marking includes: using a laser marking device to simultaneously mark the upper and lower surfaces of the composite plate with a highly focused continuous wave laser beam, the marking line spacing is 3-5mm, the laser power is 2000-2500W, the scanning speed is 250-350m / min, and a high silicon steel composite plate with a gradient distribution of silicon element content is prepared. In the warm rolling process, in the first pass, the plate is heated to 700–750°C, the rolling force is 180–200 kN, the pass reduction is 10%–12%, and the plate is asynchronously warm rolled to 1.35–1.76 mm. The speed ratio is 1.05–1.15, the lower roll is a slow roll with a constant speed, and the upper roll is a fast roll with its speed adjusted according to the speed ratio. The lower roll speed is 0.2–0.4 m / s, and the upper roll speed is 0.21–0.46 m / s. In the second pass, the rolled plate is heated to 630-680°C and then rotated 90° for cross rolling. The pass reduction rate is 6%-8%, and it is simultaneously warm rolled to 1.27-1.62 mm with a rolling force of 140-160 kN. In the third pass, the plate is rotated 90° to the length direction, heated to 550–600°C, with a rolling force of 100–120 kN, a pass reduction of 8%–10%, and asynchronously warm rolled to 1.17–1.46 mm. The speed ratio is 1.2–1.3, the lower roll is a slow roll with a constant speed, and the upper roll is a fast roll with a lower roll speed of 0.2–0.4 m / s and an upper roll speed of 0.24–0.52 m / s. In the fourth pass, the rolled plate is heated to 480-530°C and then rotated 90° for cross rolling. The pass reduction rate is 5%-7%, and it is simultaneously warm rolled to 1.11-1.38 mm with a rolling force of 70-90 kN. In the last two passes, the plate is rotated 90° to the length direction and simultaneously warm rolled at 400–450°C. The reduction rate for each pass is 8%–10%, the rolling force is 140–160 kN, and the temperature is warm rolled to 0.94–1.12 mm.

2. The method for improving the soft magnetic properties of cast-rolled orientation gradient high-silicon steel composite plates according to claim 1, characterized in that, The chemical composition of the core material, by weight percentage, is as follows: C 0.005–0.01%, Si 6.5–6.9%, Al 0.4–0.8%, Mn 0.1–0.16%, Cu 0.3–0.5%, Ta 0.5–0.9%, N 0.015–0.025%, P <0.01%, S <0.01%, O <0.003%, with the balance being Fe; The preparation of the core layer material includes: melting the core layer material in a medium-frequency vacuum induction heating furnace at a melting temperature of 1540-1570℃, then air-forging it into a 30-45 mm thick square billet at 1150-1200℃; after holding at 1150-1200℃ for 40-60 min, hot rolling it on a hot rolling mill without lubrication and hot rolling it to 5-7 mm in 6-8 passes, with an initial rolling temperature of 1100-1150℃ and a final rolling temperature of 860-880℃.

3. The method for improving the soft magnetic properties of cast-rolled orientation gradient high-silicon steel composite plates according to claim 1, characterized in that, The hot rolling process includes: hot rolling the composite plate forging obtained by casting and rolling at a heating temperature of 1130-1150℃ and holding for 20-40 min; hot rolling without lubrication on a two-roll reversible experimental hot rolling mill and hot rolling to 1.5-2 mm in 3-5 passes at an initial rolling temperature of 1100-1120℃ and a final rolling temperature of 850-870℃, followed by air cooling to room temperature.

4. The method for improving the soft magnetic properties of cast-rolled orientation gradient high-silicon steel composite plates according to claim 1, characterized in that, The first pickling process includes: pickling the hot-rolled plate after hot rolling with a 6% to 8% concentration hydrochloric acid solution at a temperature of 50 to 60°C for 15 to 25 minutes to remove surface iron oxide scale.

5. A method for improving the soft magnetic properties of cast-rolled orientation gradient high-silicon steel composite plates according to claim 1, characterized in that, The second pickling process includes: pickling the warm-rolled plate with a 6% to 8% hydrochloric acid solution at a temperature of 50 to 60°C for 15 to 25 minutes to remove surface iron oxide scale.

6. A method for improving the soft magnetic properties of cast-rolled orientation gradient high-silicon steel composite plates according to claim 1, characterized in that, The annealing process includes: continuously annealing heat treatment of the composite plate obtained by cryogenic asynchronous rolling in a heating furnace, adopting a three-stage stepwise heating annealing process, first heating to 600-700°C at a rate of 4°C / s and holding for 2-4 min, then heating to 850-950°C at a rate of 5°C / s and holding for 2-4 min, and finally heating to 1000-1100°C at a rate of 6°C / s and holding for 3-5 min, purging with nitrogen to prevent oxidation, and then air cooling to room temperature.

7. A method for improving the soft magnetic properties of cast-rolled orientation gradient high-silicon steel composite plates according to claim 1, characterized in that, The casting-rolling composite process includes: cutting the obtained core hot-rolled plate into rectangular strips of predetermined size and placing them in a casting mold, supported by 3wt% Si silicon steel gaskets in a suspended state; performing cladding casting in a vacuum electromagnetic induction heating furnace, pouring the liquid cladding metal at a target temperature of 1560-1580℃; and solidifying it in a casting-rolling composite device. Liquid casting and rolling composite is performed by leveling and rolling in a hot rolling composite unit, and then casting and rolling to 3-5 mm.

8. A method for improving the soft magnetic properties of cast-rolled orientation gradient high-silicon steel composite plates according to claim 1, characterized in that, The cryogenic rolling process includes: five passes of cryogenic rolling with a mill roll speed of 0.1–0.15 m / s, wherein the reduction rate of the first and last passes is 10%–12% and the rolling force is 160–180 kN; the reduction rate of the middle three passes is 14%–16% and the rolling force is 200–220 kN, rolling to 0.48–0.52 mm.

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