A method for manufacturing a cast and rolled oriented gradient high silicon steel clad plate

Abstract

The application discloses a preparation method of a cast-rolled oriented gradient high-silicon steel composite plate, and comprises the following steps: core layer material preparation: after core layer material is smelted in a medium-frequency vacuum induction heating furnace, the core layer material is forged into a square billet and then is subjected to hot rolling; cast-rolled compounding: the core layer hot-rolled plate is supported by a silicon steel gasket in a suspended state, and after ordinary silicon steel is coated and cast, the ordinary silicon steel is subjected to solid-liquid cast-rolled compounding with the core layer hot-rolled plate; forging, hot rolling and annealing: after the composite plate cast blank is forged, the composite plate cast blank is subjected to non-lubricated hot rolling, and after intermediate annealing, the composite plate cast blank is water-cooled to room temperature; cryogenic asynchronous rolling: after pickling treatment, single-pass cryogenic asynchronous rolling is carried out by using a cold rolling mill; diffusion annealing: the composite plate is subjected to diffusion annealing heat treatment, and argon gas is introduced for protection, so that a high-silicon steel composite plate with different silicon contents in gradient distribution is prepared; and laser marking: laser marking equipment is used to simultaneously perform laser marking on upper and lower surfaces of the composite plate, so that the soft magnetic property of the composite plate is improved.

Description

Technical Field

[0001] This invention belongs to the field of metal soft magnetic material preparation and processing technology, specifically relating to a method for preparing a cast-rolled orientation gradient high silicon steel composite plate. Background Technology

[0002] Electrical steel (silicon steel) is one of the most important functional metallic materials for manufacturing transformer cores, motors, and various electrical components. Its production process is lengthy and complex, making it a crucial indicator of a country's special steel manufacturing technology level. When the Si content in electrical steel increases to over 6.5%, not only does the iron loss reach a very low level, but the magnetostriction coefficient also decreases to near zero, offering broad application prospects in the field of high-frequency soft magnetic materials and becoming a research hotspot in the global functional materials field in recent years.

[0003] High-silicon steel soft magnetic alloys (4.5–7 wt% Si) are soft magnetic materials with low coercivity, high resistivity, and high permeability, and have broad application prospects in high-frequency fields. Currently, only chemical vapor deposition has successfully achieved the industrial production of high-silicon steel strips. However, this high-temperature silicon infiltration process requires the use of highly toxic SiCl4 gas and generates a large amount of FeCl2 waste gas, which seriously pollutes the environment.

[0004] High-silicon steel soft magnetic alloys are hard and brittle at room temperature, have high resistance to deformation, and poor processing performance. It is difficult to produce thin strips or plates that meet the requirements through conventional rolling processes, and it is even more difficult to prepare high-silicon steel thin plates with a gradient distribution of silicon content.

[0005] In existing methods for preparing high-silicon steel sheets, such as patent CN100999822A, a method for preparing high-silicon oriented silicon steel thin sheets involves using sputtering deposition to prepare Fe / Si multilayer films or Fe / Si superlattice multilayer films on ordinary silicon steel sheets. Then, Ti, Cr, Al, or MgO targets are deposited on the outer surface of the deposited layer using sputtering deposition to form AlN, TiN, MgO, and Cr spinel-type oxide coatings. Finally, low-carbon high-silicon steel thin sheets are produced by combining rolling and heat treatment. However, this method has significant drawbacks: the size of the prepared sheets is limited, the Fe / Si composition on the substrate surface is difficult to be uniform, and this method is not conducive to industrial production. For example, patent CN107900103A describes a method for preparing an orientation gradient high-silicon steel composite plate. This method involves preparing a high-silicon steel composite plate billet using a cladding casting method, followed by hot rolling and warm rolling, and then diffusion annealing to obtain a high-silicon steel sheet with silicon elements distributed in different gradients. The composite plate is then cold-rolled at room temperature to obtain a bright gradient high-silicon steel sheet with a thickness of 0.06-0.15 mm. However, this method is complex, involving hot rolling followed by warm rolling and then cold rolling, with a long warm rolling time and low production efficiency, making it unsuitable for large-scale production. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method for preparing a cast-rolled orientation gradient high-silicon steel composite plate. The method uses a new technology that combines asynchronous rolling with cryogenic treatment to prepare a novel orientation gradient high-silicon steel composite plate. Cryogenic treatment reduces the formation of ordered phases and improves the plasticity of the high-silicon steel sheet. Laser marking technology is used to improve the soft magnetic properties of the product surface, thus preparing a high-silicon steel composite plate with a gradient distribution of silicon content.

[0007] Therefore, the present invention adopts the following technical solution:

[0008] The method for preparing cast-rolled orientation gradient high-silicon steel composite plate provided by the present invention includes the following steps:

[0009] S1. Preparation of Core Material: The core material is smelted in a medium-frequency vacuum induction furnace using industrial pure iron and pure silicon with a silicon content of 99.9%. The smelting temperature is 1530℃~1580℃, yielding a core casting solution with a silicon content of 6.5%~6.9%. This solution is then forged into a 40~50mm thick square billet using air free forging at 1200℃~1250℃. Finally, the forged billet is held at 1180℃~1230℃ for 30~60min, and then hot-rolled without lubrication on a Ф450mm×450mm two-roll reversible experimental hot rolling mill, undergoing 7~9 passes to a thickness of 7.5~10mm. The initial rolling temperature is 1150~1200℃, and the final rolling temperature is 850~870℃.

[0010] S2, Casting-Rolling Composite: The core hot-rolled plate obtained in S1 is cut into rectangular strips of a certain size. These strips are suspended in a casting mold by 2.5–3.5 wt% Si silicon steel pads and cast in a vacuum electromagnetic induction heating furnace. The coating material is 2.5–3.5 wt% Si silicon steel. The liquid coating metal is poured at a target temperature of 1550–1580℃, flowing sequentially through the front box and distributor, and then into the casting-rolling composite unit to undergo solid-liquid casting-rolling composite with the core hot-rolled plate. The hot-rolling composite unit then performs leveling rolling composite with a reduction of 2–3 mm, resulting in a high-silicon steel composite plate with a surface layer (2.5–3.5 wt% Si silicon steel) and a core layer (6.5–6.9 wt% Si silicon steel).

[0011] S3. Forging: The high-silicon steel composite plate billet obtained in S2 is forged. The heating temperature is 1200-1250℃, the holding temperature is 40-70min, the forging temperature is 1150-1200℃, and the forging is forged to 3-4mm.

[0012] S4. Hot rolling: The composite plate forging in S3 is hot rolled at a heating temperature of 1150-1200℃ and held for 30-50 minutes. Then, it is hot rolled without lubrication on a two-roll reversible experimental hot rolling mill and hot rolled to 1-1.5 mm in 3-5 passes. The initial rolling temperature is 1100-1150℃ and the final rolling temperature is 870-900℃. Then, it is air-cooled to room temperature.

[0013] S5. Intermediate annealing: The intermediate annealing temperature is 920-960℃. After holding at this temperature for 10-20 minutes, the temperature is cooled to room temperature by water.

[0014] S6. Pickling: Use a 6% to 8% hydrochloric acid solution to pickle the hot-rolled plate and intermediate annealed plate. The pickling temperature is 50 to 60℃ and the pickling time is 15 to 25 minutes to remove the iron oxide scale on the surface.

[0015] S7. Cryogenic Asynchronous Rolling: A single-pass cryogenic asynchronous rolling process with a reduction rate of 50%–60% is performed using a four-high cold rolling mill to roll high-silicon steel sheets to a thickness of 0.5–0.6 mm. The speed ratio is 1.2–1.4, with the lower roll being a slow roll whose speed remains constant, and the upper roll being a fast roll whose speed is adjusted according to the speed ratio. The lower roll speed is 0.15–0.25 m / s, and the upper roll speed is 0.18–0.35 m / s. The rolling force is 130–150 kN. Before cryogenic asynchronous rolling, the rolls are turned on and rotated under zero load. The upper and lower work rolls are cooled using nitrogen cooling guns to achieve a roll surface temperature of -180 to -100℃. Before rolling, the high-silicon steel composite plate needs to be cooled in liquid nitrogen to a temperature between -180 and -100℃. After cooling, the composite plate is quickly removed for cryogenic asynchronous rolling.

[0016] S8. Diffusion annealing: The composite plate obtained in S7 is subjected to diffusion annealing heat treatment in a heating furnace. The heating temperature is between 1150 and 1200℃, and the holding time is 100 to 150 minutes. Argon gas is introduced throughout the process for protection, so as to prepare high silicon steel composite plates with different silicon contents in a gradient distribution.

[0017] S9. Laser marking: A laser marking device is used to simultaneously mark the upper and lower surfaces of the composite board with a highly focused continuous wave laser beam. The marking line spacing is 3-5mm, the laser power is 1500-2500W, and the scanning speed is 200-300m / min.

[0018] The beneficial effects of this invention are as follows: The high-silicon steel casting-rolling composite preparation technology uses a plastic ordinary silicon steel cladding to coat and protect the brittle and difficult-to-deform high-silicon steel core layer. During the solid-liquid casting-rolling composite process, the casting rolls form localized strong stresses at the troughs of the corrugated composite strip, while during the hot rolling composite process, the flat rolls form localized strong stresses at the crests of the corrugated composite strip. This can promote the rolling composite of dissimilar metals, reduce residual stress, significantly improve the interfacial bonding strength, and achieve metallurgical bonding of high-silicon steel composite plates with different silicon contents in a gradient distribution. In addition, compared with the B2-DO3 transformation, the A2-B2 transformation is faster, and the B2 ordered phase with nearest-neighbor matching of dissimilar atoms can be formed quickly. The A2-B2 transformation is more likely to occur than the B2-DO3 transformation, so a small amount of B2 ordered phase can still be retained in the hot-rolled plate using water cooling. Compared to water cooling, cryogenic rolling involves lower temperatures. Using cryogenic asynchronous rolling technology to prepare high-silicon steel composite plates can completely suppress the formation of the DO3 ordered phase and prevent the coalescence and growth of the B2 ordered phase. This significantly reduces the content of ordered phases and the antiphase domain boundary energy in the steel, pushing it towards disorder and laying a solid foundation for further rolling processing. Asynchronous rolling, as an effective method of deep plastic deformation, induces additional shear deformation in the deformation zone of the workpiece using two work rolls rotating at different speeds. This induces crystal rotation, improves equivalent strain, and achieves grain refinement. Cryogenic asynchronous rolling has low requirements for processing equipment, a simple and feasible production process, and promising prospects for industrial application. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 The macroscopic morphology of the composite plate after cryogenic asynchronous rolling in Example 3;

[0021] Figure 2 The diagram shows the three-point bending performance after cryogenic asynchronous rolling in Examples 1-3.

[0022] Figure 3 The images show scanning electron microscope (SEM) images and reverse-phase domain transmission electron microscope (TEM) images of the dislocation configuration in the core of the composite plate after cryogenic asynchronous rolling in Example 3. Detailed Implementation

[0023] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0024] Example 1

[0025] Example 1 provides a method for preparing a cast-rolled orientation gradient high-silicon steel composite plate, the method comprising the following steps:

[0026] S11. Preparation of core layer material: The core layer material was smelted in a medium-frequency vacuum induction furnace using industrial pure iron and pure silicon with a silicon content of 99.9%. The smelting temperature was 1530℃, yielding a core layer casting solution with a silicon content of 6.5%. This solution was then forged into a 40mm thick square billet using air free forging at 1200℃. Finally, after holding the billet at 1180℃ for 60 minutes, it was hot-rolled without lubrication on a Ф450mm×450mm two-roll reversible experimental hot rolling mill, undergoing seven passes to a thickness of 10mm. The initial rolling temperature was 1150℃, and the final rolling temperature was 850℃.

[0027] S12, Casting-Rolling Composite: The core hot-rolled plate obtained in S11 is cut into rectangular strips of a certain size. These strips are suspended in a casting mold by 2.5wt% Si silicon steel pads and cast in a vacuum electromagnetic induction heating furnace. The coating material is 2.5wt% Si silicon steel. The liquid coating metal is poured at a target temperature of 1550℃, flowing sequentially through the front box and distributor, and then into the casting-rolling composite device to undergo solid-liquid casting-rolling composite with the core hot-rolled plate. The hot-rolling composite device then performs leveling rolling composite with a reduction of 2mm, resulting in a high-silicon steel composite plate with a surface layer (2.5wt% Si silicon steel) and a core layer (6.5wt% Si silicon steel).

[0028] S13. Forging: The high silicon steel composite plate billet obtained in S12 is forged. The heating temperature is 1200℃, the holding temperature is 70min, the forging temperature is 1150℃, and the forging is forged to 4mm.

[0029] S14. Hot rolling: The composite plate forging in S13 is hot rolled at a heating temperature of 1200℃ and held for 30 minutes. Then, it is hot rolled without lubrication on a two-roll reversible experimental hot rolling mill and hot rolled to 1.5mm in 5 passes. The initial rolling temperature is 1150℃ and the final rolling temperature is 900℃. Then, it is air-cooled to room temperature.

[0030] S15. Intermediate annealing: The intermediate annealing temperature is 960℃, and after holding at that temperature for 10 minutes, it is water-cooled to room temperature.

[0031] S16. Pickling: The hot-rolled plate and intermediate annealed plate are pickled with an 8% hydrochloric acid solution at a temperature of 50°C for 15 minutes to remove the surface iron oxide scale.

[0032] S17. Cryogenic Asynchronous Rolling: A single-pass cryogenic asynchronous rolling process with a reduction rate of 60% is performed using a four-roll cold rolling mill to roll a high-silicon steel sheet to a thickness of 0.6 mm. The speed ratio is 1.2, with the lower roll being a slow roll whose speed remains constant, and the upper roll being a fast roll whose speed is adjusted according to the speed ratio. The lower roll speed is 0.15 m / s, and the upper roll speed is 0.18 m / s. The rolling force is 130 kN. Before cryogenic asynchronous rolling, the rolls are turned on and rotated under zero load. The upper and lower work rolls are cooled using a nitrogen cooling gun to achieve a roll surface temperature of -100℃. Before rolling, the high-silicon steel composite plate needs to be cooled in liquid nitrogen to a temperature of -100℃. After cooling, the composite plate is quickly removed for cryogenic asynchronous rolling.

[0033] S18. Diffusion annealing: The composite plate obtained in S17 is subjected to diffusion annealing heat treatment in a heating furnace at a heating temperature of 1200℃ and a holding time of 100min. Argon gas is introduced throughout the process for protection, thus preparing high silicon steel composite plates with different silicon contents in a gradient distribution.

[0034] S19. Laser marking: A laser marking device is used to simultaneously mark the upper and lower surfaces of the composite board with a highly focused continuous wave laser beam. The marking line spacing is 3mm, the laser power is 2500W, and the scanning speed is 200m / min.

[0035] Example 2

[0036] Example 2 provides a method for preparing a cast-rolled orientation gradient high-silicon steel composite plate, the method comprising the following steps:

[0037] S21. Preparation of core layer material: The core layer material was smelted in a medium-frequency vacuum induction furnace using industrial pure iron and pure silicon with a silicon content of 99.9%. The smelting temperature was 1550℃, resulting in a core layer casting solution with a silicon content of 6.7%. This solution was then forged into a 45mm thick square billet using air free forging at 1230℃. Finally, after holding the billet at 1200℃ for 45 minutes, it was hot-rolled without lubrication on a Ф450mm×450mm two-roll reversible experimental hot rolling mill, undergoing eight passes to a thickness of 9mm. The initial rolling temperature was 1180℃, and the final rolling temperature was 860℃.

[0038] S22, Casting-Rolling Composite: The core hot-rolled plate obtained in S21 is cut into rectangular strips of a certain size. These strips are suspended in a casting mold by 3wt% Si silicon steel spacers and then cast in a vacuum electromagnetic induction heating furnace. The coating material is 3wt% Si silicon steel. The liquid coating metal is poured at a target temperature of 1560℃, flowing sequentially through the front box and distributor, and then into the casting-rolling composite device to undergo solid-liquid casting-rolling composite with the core hot-rolled plate. The hot-rolling composite device then performs leveling rolling composite with a reduction of 2.5mm, resulting in a high-silicon steel composite plate with a surface layer (3wt% Si silicon steel) and a core layer (6.7wt% Si silicon steel).

[0039] S23. Forging: The high silicon steel composite plate billet obtained in S22 is forged. The heating temperature is 1230℃, the holding temperature is 50min, the forging temperature is 1170℃, and the forging is forged to 3.5mm.

[0040] S24. Hot rolling: The composite plate forging in S23 is hot rolled at a heating temperature of 1170℃ and held for 40 minutes. Then, it is hot rolled without lubrication on a two-roll reversible experimental hot rolling mill and hot rolled to 1.2 mm in 4 passes. The initial rolling temperature is 1130℃ and the final rolling temperature is 880℃. Then, it is air-cooled to room temperature.

[0041] S25. Intermediate annealing: The intermediate annealing temperature is 940℃, and after holding at that temperature for 15 minutes, it is water-cooled to room temperature.

[0042] S26. Pickling: The hot-rolled plate and intermediate annealed plate are pickled with a 7% hydrochloric acid solution at a temperature of 55°C for 20 minutes to remove the surface iron oxide scale.

[0043] S27. Cryogenic Asynchronous Rolling: A single-pass cryogenic asynchronous rolling process with a reduction rate of 54% is performed using a four-roll cold rolling mill to roll a high-silicon steel sheet to a thickness of 0.55 mm. The speed ratio is 1.3, with the lower roll being a slow roll whose speed remains constant, and the upper roll being a fast roll whose speed is adjusted according to the speed ratio. The lower roll speed is 0.2 m / s, and the upper roll speed is 0.26 m / s. The rolling force is 140 kN. Before cryogenic asynchronous rolling, the rolls are turned on and rotated under zero load. The upper and lower work rolls are cooled using a nitrogen cooling gun to achieve a roll surface temperature of -150°C. Before rolling, the high-silicon steel composite plate needs to be cooled in liquid nitrogen to a temperature of -150°C. After cooling, the composite plate is quickly removed for cryogenic asynchronous rolling.

[0044] S28. Diffusion annealing: The composite plate obtained in S27 is subjected to diffusion annealing heat treatment in a heating furnace at a heating temperature of 1170℃ and a holding time of 120min. Argon gas is introduced throughout the process for protection, thus preparing high silicon steel composite plates with different silicon contents in a gradient distribution.

[0045] S29. Laser marking: A laser marking device is used to simultaneously mark the upper and lower surfaces of the composite board with a highly focused continuous wave laser beam. The marking line spacing is 4mm, the laser power is 2000W, and the scanning speed is 250m / min.

[0046] Example 3

[0047] like Figure 1-3 As shown in Example 3, a method for preparing a cast-rolled orientation gradient high-silicon steel composite plate is provided. The method includes the following steps:

[0048] S31. Preparation of core layer material: The core layer material was smelted in a medium-frequency vacuum induction furnace using industrial pure iron and pure silicon with a silicon content of 99.9%. The smelting temperature was 1580℃, yielding a core layer casting solution with a silicon content of 6.9%. This solution was then forged into a 50mm thick square billet using air free forging at 1250℃. Finally, after holding the billet at 1230℃ for 30 minutes, it was hot-rolled without lubrication on a Ф450mm×450mm two-roll reversible experimental hot rolling mill, undergoing nine passes to a thickness of 7.5mm. The initial rolling temperature was 1200℃, and the final rolling temperature was 870℃.

[0049] S32, Casting-Rolling Composite: The core hot-rolled plate obtained in S31 is cut into rectangular strips of a certain size. These strips are suspended in a casting mold by 3.5wt% Si silicon steel spacers and cast in a vacuum electromagnetic induction heating furnace. The coating material is 3.5wt% Si silicon steel. The liquid coating metal is poured at a target temperature of 1580℃, flowing sequentially through the front box and distributor, and then into the casting-rolling composite device to undergo solid-liquid casting-rolling composite with the core hot-rolled plate. The hot-rolling composite device then performs leveling rolling composite with a reduction of 3mm, resulting in a high-silicon steel composite plate with a surface layer (3.5wt% Si silicon steel) and a core layer (6.9wt% Si silicon steel).

[0050] S33. Forging: The high silicon steel composite plate billet obtained in S32 is forged. The heating temperature is 1250℃, the holding temperature is 40min, the forging temperature is 1200℃, and the forging is forged to 3mm.

[0051] S34. Hot rolling: The composite plate forging in S33 is hot rolled at a heating temperature of 1150℃ and held for 50 minutes. Then, it is hot rolled without lubrication on a two-roll reversible experimental hot rolling mill and hot rolled to 1 mm in 3 passes. The initial rolling temperature is 1100℃ and the final rolling temperature is 870℃. Then, it is air-cooled to room temperature.

[0052] S35. Intermediate annealing: The intermediate annealing temperature is 920℃, and after holding at that temperature for 20 minutes, it is water-cooled to room temperature.

[0053] S36. Pickling: Hot-rolled plates and intermediate annealed plates are pickled using a 6% hydrochloric acid solution at a temperature of 60°C for 25 minutes to remove surface iron oxide scale.

[0054] S37. Cryogenic Asynchronous Rolling: A single-pass cryogenic asynchronous rolling process with a reduction rate of 50% is performed using a four-roll cold rolling mill to roll a high-silicon steel sheet to a thickness of 0.5mm. The speed ratio is 1.4, with the lower roll being a slow roll whose speed remains constant, and the upper roll being a fast roll whose speed is adjusted according to the speed ratio. The lower roll speed is 0.25m / s, and the upper roll speed is 0.35m / s. The rolling force is 130–150kN. Before cryogenic asynchronous rolling, the rolls are turned on and rotated under zero load. The upper and lower work rolls are cooled using a nitrogen cooling gun to achieve a roll surface temperature of -180℃. Before rolling, the high-silicon steel composite plate needs to be cooled in liquid nitrogen to a temperature of -180℃. After cooling, the composite plate is quickly removed for cryogenic asynchronous rolling.

[0055] S38. Diffusion annealing: The composite plate obtained in S37 is subjected to diffusion annealing heat treatment in a heating furnace at a heating temperature of 1150℃ and a holding time of 150min. Argon gas is introduced throughout the process for protection, thus preparing high silicon steel composite plates with different silicon contents in a gradient distribution.

[0056] S39. Laser marking: A laser marking device is used to simultaneously mark the upper and lower surfaces of the composite board with a highly focused continuous wave laser beam. The marking line spacing is 5mm, the laser power is 1500W, and the scanning speed is 300m / min.

[0057] like Figure 3 As shown, Figure 3 (a) shows the dislocation configuration of the core in Example 3; Figure 3 (b) is the antiphase domain of the core in Example 3; as can be seen from the figure, the generation of a large number of dislocations in the cryogenic asynchronous composite plate is conducive to dislocation slip, and the B2 ordered structure after cryogenic treatment is extremely small, which is conducive to improving the plastic deformation ability of the rolled composite plate.

[0058] In the three embodiments described above, in Embodiment 1, the velocity ratio of cryogenic asynchronous rolling was 1.2, and the rolling temperature was -100℃; in Embodiment 2, the velocity ratio was 1.3, and the rolling temperature was -150℃; in Embodiment 3, the velocity ratio of cryogenic asynchronous rolling was 1.4, and the rolling temperature was -180℃. With the increase of the velocity ratio, the recrystallized grains of the finished thin plate gradually become finer. Furthermore, the increase in cryogenic asynchronous rolling temperature inhibits the formation of the DO3 ordered phase, facilitates the cutting of the B2 ordered structure by a large number of slip dislocations, prevents the merging and growth of the B2 ordered phase, significantly reduces the ordered phase content and antiphase domain boundary energy in the steel, and significantly improves the material's plastic deformation capacity. Figure 2It can be seen that, in the three embodiments, the plastic deformation capacity of the finished sheet gradually increases with the increase of the different speed ratio and the deep cryogenic rolling temperature.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a cast-rolled, grain-oriented, high-silicon steel composite plate, characterized in that, The method includes: core material preparation, casting-rolling composite, forging, hot rolling, intermediate annealing, pickling, cryogenic asynchronous rolling, diffusion annealing, and laser marking; Preparation of core material: The core material is smelted in a medium-frequency vacuum induction furnace. The raw materials are industrial pure iron and pure silicon with a silicon content of 99.9%. The smelting temperature is 1530℃~1580℃ to obtain a core casting solution with a silicon content of 6.5%~6.9%. Then, the ingot is forged into a square billet with a thickness of 40~50 mm by air free forging at 1200℃~1250℃. Finally, the forged billet is held at 1180℃~1230℃ for 30~60 min and then hot rolled without lubrication on a Ф 450 mm×450 mm two-roll reversible experimental hot rolling mill. It is then hot rolled to 7.5~10 mm in 7~9 passes. The initial rolling temperature is 1150~1200℃ and the final rolling temperature is 850~870℃. The casting-rolling composite process includes: cutting the core hot-rolled plate into rectangular strips of a certain size, suspending them in a casting mold with 2.5–3.5 wt% Si silicon steel pads, and casting them in a vacuum electromagnetic induction heating furnace, with the cladding material being 2.5–3.5 wt% Si silicon steel; pouring the liquid cladding metal at a target temperature of 1550–1580°C, flowing sequentially through the front box and the distributor, and entering the casting-rolling composite device to solidify with the core hot-rolled plate. Liquid casting and rolling composite, followed by leveling and rolling composite in a hot rolling composite device with a reduction of 2-3 mm, to prepare a high-silicon steel composite plate; the high-silicon steel composite plate comprises: a surface layer of 2.5-3.5 wt% Si silicon steel and a core layer of 6.5-6.9 wt% Si silicon steel; The cryogenic asynchronous rolling process involves single-pass cryogenic asynchronous rolling with a reduction rate of 50%–60% using a four-roll cold rolling mill, rolling high-silicon steel sheets to a thickness of 0.5–0.6 mm. The speed ratio is 1.2–1.4, with the lower roll being a slow roll whose speed remains constant, and the upper roll being a fast roll whose speed is adjusted according to the speed ratio. The lower roll speed is 0.15–0.25 m / s, and the upper roll speed is 0.18–0.35 m / s. The rolling force is 130–150 kN. Before cryogenic asynchronous rolling, the rolls are turned on and rotated under zero load. The upper and lower work rolls are cooled using a nitrogen cooling gun to achieve a roll surface temperature of -180 to -100°C. Before rolling, the high-silicon steel composite plate needs to be cooled in liquid nitrogen to a temperature between -180 and -100°C. After cooling, the composite plate is quickly removed for cryogenic asynchronous rolling.

2. The method for preparing a cast-rolled orientation gradient high-silicon steel composite plate according to claim 1, characterized in that, The forging process includes: The high-silicon steel composite plate billet is forged by heating at 1200-1250℃, holding at 40-70 min, forging at 1150-1200℃, and forging to 3-4 mm.

3. The method for preparing a cast-rolled orientation gradient high-silicon steel composite plate according to claim 1, characterized in that, The hot rolling includes: The composite plate forging billet is hot rolled at a heating temperature of 1150-1200℃ and held for 30-50 min. Then, it is hot rolled without lubrication on a two-roll reversible experimental hot rolling mill and hot rolled to 1-1.5 mm in 3-5 passes. The initial rolling temperature is 1100-1150℃ and the final rolling temperature is 870-900℃. Then, it is air-cooled to room temperature.

4. The method for preparing a cast-rolled orientation gradient high-silicon steel composite plate according to claim 1, characterized in that, The intermediate annealing includes: an intermediate annealing temperature of 920-960℃, holding at that temperature for 10-20 minutes, followed by water cooling to room temperature.

5. The method for preparing a cast-rolled orientation gradient high-silicon steel composite plate according to claim 1, characterized in that, The pickling process includes: pickling the hot-rolled plate and intermediate annealed plate with a 6% to 8% hydrochloric acid solution at a pickling temperature of 50 to 60°C for 15 to 25 minutes to remove surface iron oxide scale.

6. The method for preparing a cast-rolled orientation gradient high-silicon steel composite plate according to claim 1, characterized in that, The diffusion annealing includes: performing diffusion annealing heat treatment on the composite plate in a heating furnace, with a heating temperature between 1150 and 1200°C, a holding time of 100 to 150 minutes, and argon gas protection throughout the process, to prepare high-silicon steel composite plates with different silicon contents in a gradient distribution.

7. The method for preparing a cast-rolled orientation gradient high-silicon steel composite plate according to claim 1, characterized in that, The laser marking includes: using a laser marking device to simultaneously mark the upper and lower surfaces of the composite board with a highly focused continuous wave laser beam, with a marking line spacing of 3-5 mm, a laser power of 1500-2500 W, and a scanning speed of 200-300 m / min.

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