High-grade thin-gauge non-oriented silicon steel 35w360 and preparation method thereof

Abstract

The application discloses high-grade thin-gauge non-oriented silicon steel 35W360 and a preparation method thereof. The non-oriented silicon steel has the following chemical components in percentage by mass: C: <0.0030%, Si: 2.30-2.70%, Mn: 0.35-0.60%, P: <0.020%, S: <0.003%, Al: 0.45-0.65%, N: <0.0030%, O: <0.0020%, Ti: <0.0025%, and the rest is Fe and inevitable inclusions, and the total percentage by mass is 100%. The application adopts reasonable components and process design, and produces thin-gauge non-oriented silicon steel with high magnetic properties through the following procedures: hot metal desulfurization-smelting-vacuum treatment-continuous casting-hot continuous rolling-normalization pickling-cold rolling-annealing coating.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metallurgical materials, in particular to a high-grade thin-gauge non-oriented silicon steel 35W360 and a preparation method thereof, and the material is mainly used for producing high-grade thin-gauge non-oriented silicon steel, manufacturing compressor motors, general motors and the like, and the cores of electric reactors and small power transformers. BACKGROUND

[0002] At present, the high magnetic induction non-oriented silicon steel and the production method thereof disclosed in application No. 202311510499.6 are focused on controlling the precipitated phase, appropriately reducing the iron loss, and effectively improving the magnetic induction. The present application focuses on the preparation process and process parameter control of high-grade thin-gauge non-oriented silicon steel, so as to ensure that the product meets the use requirements of high-efficiency motors in terms of low iron loss and high magnetic induction.

[0003] Application No. 202311553542.7 discloses a high-performance non-oriented silicon steel and a manufacturing method thereof. The present application focuses on adding special alloys and process control to improve the magnetic properties of non-oriented silicon steel. The present application only uses Si-Mn-Al alloying, combined with a reasonable full-process production process, to obtain 0.35mm thin-gauge high-magnetic non-oriented silicon steel.

[0004] Application No. 202311818890.2 discloses a non-oriented silicon steel and a preparation method thereof. The present application focuses on controlling the Si content to reduce the columnar crystal growth rate during the solidification process of the casting blank, improve the equiaxed crystal ratio, and reduce the corrugated defects. The present application focuses on the full-process production of high-magnetic thin-gauge non-oriented silicon steel, and details the control parameters of each process, finally producing low-iron loss and high-magnetic non-oriented silicon steel. SUMMARY

[0005] The purpose of the present application is to provide a high-grade thin-gauge non-oriented silicon steel 35W360 and a preparation method thereof, to produce thin-gauge non-oriented silicon steel with high magnetic properties.

[0006] In order to implement the policy of national double carbon and energy efficiency level improvement, achieve energy saving and emission reduction, and improve the efficiency of motors, major silicon steel enterprises focus on the development of high-grade thin-gauge non-oriented silicon steel. When the power of the motor remains unchanged, the higher the magnetic induction of the silicon steel sheet, the smaller the cross-sectional area of the core, which reduces the volume and weight of the core, and reduces the total loss and manufacturing cost of the motor; the thinner the silicon steel sheet, the lower the iron loss, which can reduce the total loss of the motor, and small motors can be made. The present application adopts reasonable composition and process design, through the processes of hot metal desulfurization-smelting-vacuum treatment-continuous casting-hot continuous rolling-normalization-pickling-cold rolling-annealing-coating, to produce thin-gauge non-oriented silicon steel with high magnetic properties.

[0007] To solve the above technical problems, the present application adopts the following technical solutions:

[0008] The application discloses a high-grade thin-gauge non-oriented silicon steel 35W360, and chemical components in mass percentage are as follows: C: <0.0030%, Si: 2.30-2.70%, Mn: 0.35-0.60%, P: <0.020%, S: <0.003%, Al: 0.45-0.65%, N: <0.0030%, O: <0.0020%, Ti: <0.0025%, and the rest is Fe and inevitable inclusions, and the total is 100%.

[0009] The application discloses a preparation method of the high-grade thin-gauge non-oriented silicon steel 35W360.

[0010] KR desulfurization treatment is adopted to control the sulfur content in molten iron to be less than or equal to 0.002%; low-sulfur scrap steel is used in converter smelting; deep decarburization treatment is carried out in RH, and Al particles are added to ensure that pure degassing time is not less than 5 minutes;

[0011] Oxidation-free casting is carried out in the whole continuous casting process, electromagnetic stirring is used to ensure that the equiaxed crystal rate of the casting blank is not less than 50%, and a small amount of columnar crystal is generated; the slab thickness is 230 mm;

[0012] The slab is hot charged into a walking beam heating furnace, the charging temperature is 350-500 DEG C, the heating temperature is 1130-1155 DEG C, the soaking time in the soaking section is 30-45 minutes, and as few precipitates as possible are ensured to be dissolved, so that as few fine precipitates as possible are generated in the hot rolling process;

[0013] In order to break the columnar crystal as much as possible, the first-pass reduction of the rough rolling is not less than 50 mm, the intermediate blank thickness is 36 mm, the first-pass reduction of the finish rolling is 40%, the last-pass reduction is 12%, the final rolling temperature is 845-870 DEG C, the coiling temperature is 620-650 DEG C, and the hot rolling specification is 1.8-2.0 mm;

[0014] The normalizing soaking temperature is 930-940 DEG C, the soaking time is 1.2-1.5 minutes, the deformed structure in the center of the hot rolling is ensured to be recrystallized, and more deformation bands are generated in the cold rolling;

[0015] After 5-pass cold rolling to a thickness of 0.35 mm, the total cold rolling reduction is controlled to be 78-82%, so that {111} texture is generated less and weakly;

[0016] The continuous annealing soaking temperature is 930-940 DEG C, the soaking time is 30-40 seconds, the steel strip reaches the annealing temperature before the annealing soaking section, the grains begin to recrystallize, the grains grow in the soaking process, and the iron loss is reduced;

[0017] The coating thickness is 3.2-3.3 g / m 2 ;

[0018] Finally, the 0.35 mm thin gauge high grade non-oriented silicon steel meeting the magnetic property requirements is prepared.

[0019] Further, the steps include the following:

[0020] Step a: KR desulfurization treatment is used, the sulfur content in the molten iron is controlled to be 0.002%, low-sulfur scrap steel is used in the converter, RH vacuum treatment is used, aluminum particles are added to configure Al, the Al element is controlled to be above the upper limit to ensure the content after Al loss in the casting machine process, and the vacuum degassing time is 6 min;

[0021] Step b: continuous casting is performed in a whole process protection non-oxidation casting mode, a roller electromagnetic stirring is used to ensure that the equiaxed crystal rate is not less than 50%, the drawing speed is 0.90 m / min, and the slab thickness is 230 mm. C: 0.0030%, Si: 2.55%, Mn: 0.48%, P: 0.018%, S: 0.002%, Als: 0.51%, N: 0.0022%, O: 0.0018%, Ti: 0.0020%, and the balance is Fe and impurities;

[0022] Step c: the slab is hot charged into the walking beam heating furnace, the charging temperature is 385 ℃, the heating temperature is 1142 ℃, and the soaking time is 38 min;

[0023] Step d: the first pass reduction of the rough rolling is 55 mm, the intermediate billet thickness is 36 mm, the first pass reduction of the finish rolling is 39%, the last pass reduction is 11.8%, the final rolling temperature is 856 ℃, the coiling temperature is 628 ℃, and the hot rolling specification is 1.8 mm;

[0024] Step e: the normalizing is performed at a rapid temperature rise to about 800 ℃, the temperature in the holding section is 935 ℃, and the holding time is 1.5 min;

[0025] Step f: the cold rolling is performed for 5 passes to 0.35 mm;

[0026] Step g: annealing is performed in a continuous annealing furnace, the annealing holding temperature is 932 ℃, and the holding time is 38 s. Step h: an environmentally friendly coating is used to coat an insulation layer, and the coating thickness is 3.3 g / m 2 .

[0027] Further, the steps include the following:

[0028] Step a: KR desulfurization treatment is used, the sulfur content in the molten iron is controlled to be 0.001%, low-sulfur scrap steel is used in the converter, RH vacuum treatment is used, aluminum particles are added to configure Al, the Al element is controlled to be above the upper limit to ensure the content after Al loss in the casting machine process, and the vacuum degassing time is 5.5 min;

[0029] Step b: continuous casting with full protection against oxidation, using roll electromagnetic stirring to ensure that the equiaxed crystal ratio is not less than 50%, a drawing speed of 0.92 m / min, and a slab thickness of 230 mm. C: 0.0028%, Si: 2.48%, Mn: 0.52%, P: 0.018%, S: 0.001%, Als: 0.55%, N: 0.0020%, O: 0.0018%, Ti: 0.0019%, the balance being Fe and impurities;

[0030] Step c: hot charging of the slab into a walking beam furnace, a charging temperature of 392°C, a heating temperature of 1143°C, and a soaking time of 41 min;

[0031] Step d: a first pass reduction of 52 mm, an intermediate billet thickness of 36 mm, a first pass reduction of 39.2% in the finishing rolling, a last pass reduction of 12.3%, a final rolling temperature of 863°C, a coiling temperature of 633°C, and a hot rolling specification of 2.0 mm;

[0032] Step e: rapid heating to about 800°C during normalizing, a holding temperature of 931°C during the holding period, and a holding time of 1.4 min;

[0033] Step f: cold rolling to 0.35 mm through 5 passes;

[0034] Step g: annealing in a continuous annealing furnace, an annealing holding temperature of 935°C, and a holding time of 36 s;

[0035] Step h: coating an insulation layer using an environmentally friendly coating, a coating thickness of 3.2 g / m 2 .

[0036] Further, the steps include the following:

[0037] Step a: desulfurization treatment using the KR method, with the sulfur content in the molten iron controlled at 0.001%, low-sulfur scrap steel used in the converter, RH vacuum treatment, and addition of aluminum particles to control the Al element above the limit to ensure the content after Al loss in the casting process, and a vacuum degassing time of 5.8 min;

[0038] Step b: continuous casting with full protection against oxidation, using roll electromagnetic stirring to ensure that the equiaxed crystal ratio is not less than 50%, a drawing speed of 0.93 m / min, and a slab thickness of 230 mm. C: 0.0027%, Si: 2.58%, Mn: 0.52%, P: 0.017%, S: 0.001%, Als: 0.49%, N: 0.0019%, O: 0.0016%, Ti: 0.0018%, the balance being Fe and impurities;

[0039] Step c: hot charging of the slab into a walking beam furnace, a charging temperature of 402°C, a heating temperature of 1145°C, and a soaking time of 42 min;

[0040] Step d: rough rolling first pass reduction 53mm, intermediate blank thickness 36mm, finishing rolling first pass reduction rate 39.5%, last pass reduction rate 12.5%, finish rolling temperature 865℃, coiling temperature 636℃, hot rolling specification 1.8mm;

[0041] Step e: normalizing, quickly heating to about 800℃, holding temperature 938℃, holding time 1.3min;

[0042] Step f: cold rolling to 0.35mm through 5 passes;

[0043] Step g: annealing in a continuous annealing furnace, annealing holding temperature 935℃, holding time 35s;

[0044] Step h: using an environmental protection coating to coat an insulation layer, coating thickness 3.2g / m 2 .

[0045] Compared with the prior art, the beneficial technical effects of the present application are:

[0046] Through the detailed production process and parameter introduction, the present application produces 0.35mm thin specification high grade non-oriented silicon steel, the magnetic performance meets the design requirements, and can be successfully applied to the cores of compressors, general motors and other motors, and transformers of electric reactors and other household appliances. With the thinning of non-oriented silicon steel, the iron loss will be reduced, but the iron loss and magnetic induction are in a contradictory relationship of rising and falling together, low iron loss is beneficial to reducing energy consumption, and high magnetic induction is beneficial to the miniaturization of motors, the iron loss of the present application can reach below 2.8W / kg, and the magnetic induction can reach above 1.68T, which is a very large improvement compared with the national standard of 1.63T, so it is very difficult to simultaneously achieve low iron loss and high magnetic induction, and it is more difficult to improve the magnetic induction than to reduce the iron loss. BRIEF DESCRIPTION OF DRAWINGS

[0047] The present application will be further described below in combination with the drawings.

[0048] Figure 1 The organization and texture of Example 1;

[0049] Figure 2 The organization and texture of Example 2;

[0050] Figure 3 The organization and texture of Example 3. DETAILED DESCRIPTION

[0051] The present application will be further described below in combination with the drawings.

[0052] Embodiment 1-3 is a high-grade thin-gauge non-oriented silicon steel 35W360 and a process step adopted in the preparation method thereof.

[0053] Embodiment 1:

[0054] Step a: KR desulfurization treatment is adopted, the sulfur content in the molten iron is controlled to be 0.002%, low-sulfur scrap steel is adopted in the converter, RH vacuum treatment is adopted, aluminum particles are added to configure Al, the Al element is controlled to be above the upper limit to ensure the content after Al loss in the casting machine process, and the vacuum degassing time is 6 min.

[0055] Step b: continuous casting is performed in a whole-process protection non-oxidation casting mode, a roller electromagnetic stirring is used to ensure that the equiaxed crystal rate is not less than 50%, the drawing speed is 0.90 m / min, and the slab thickness is 230 mm. C: 0.0030%, Si: 2.55%, Mn: 0.48%, P: 0.018%, S: 0.002%, Als: 0.51%, N: 0.0022%, O: 0.0018%, and Ti: 0.0020%.

[0056] Step c: the slab is hot-charged into a walking beam furnace, the charging temperature is 385 ℃, the heating temperature is 1142 ℃, and the soaking time is 38 min.

[0057] Step d: the first-pass reduction amount of rough rolling is 55 mm, the intermediate billet thickness is 36 mm, the first-pass reduction rate of finish rolling is 39%, the last-pass reduction rate is 11.8%, the final rolling temperature is 856 ℃, the coiling temperature is 628 ℃, and the hot-rolled specification is 1.8 mm.

[0058] Step e: the normalizing is performed at a rapid heating to 800 ℃, the soaking temperature is 935 ℃, and the soaking time is 1.5 min.

[0059] Step f: the cold rolling is performed through 5 passes to 0.35 mm.

[0060] Step g: annealing is performed in a continuous annealing furnace, the annealing soaking temperature is 932 ℃, and the soaking time is 38 s.

[0061] Step h: an environmentally friendly coating is used to coat an insulation layer, and the coating thickness is 3.3 g / m 2 .

[0062] Embodiment 2:

[0063] Step a: KR desulfurization treatment is adopted, the sulfur content in the molten iron is controlled to be 0.001%, low-sulfur scrap steel is adopted in the converter, RH vacuum treatment is adopted, aluminum particles are added to configure Al, the Al element is controlled to be above the upper limit to ensure the content after Al loss in the casting machine process, and the vacuum degassing time is 5.5 min.

[0064] Step b: Continuous casting with full protection against oxidation, using roll-type electromagnetic stirring to ensure an equiaxed crystal ratio of not less than 50%, a withdrawal speed of 0.92 m / min, and a slab thickness of 230 mm. C: 0.0028%, Si: 2.48%, Mn: 0.52%, P: 0.018%, S: 0.001%, Als: 0.55%, N: 0.0020%, O: 0.0018%, Ti: 0.0019%.

[0065] Step c: Hot charging of the slab into the walking beam furnace, a charging temperature of 392°C, a heating temperature of 1143°C, and a soaking time of 41 min.

[0066] Step d: A rough rolling first pass reduction of 52 mm, an intermediate slab thickness of 36 mm, a first pass reduction rate of 39.2% in the finishing rolling, a last pass reduction rate of 12.3%, a finish rolling temperature of 863°C, a coiling temperature of 633°C, and a hot rolling gauge of 2.0 mm.

[0067] Step e: Rapid heating to 800°C during normalizing, a soaking temperature of 931°C during the soaking period, and a soaking time of 1.4 min.

[0068] Step f: Cold rolling through 5 passes to 0.35 mm.

[0069] Step g: Annealing in a continuous annealing furnace, an annealing soaking temperature of 935°C, and a soaking time of 36 s.

[0070] Step h: Using an environmentally friendly coating to coat an insulating layer, a coating thickness of 3.2 g / m 2 .

[0071] Example 3:

[0072] Step a: Desulfurization treatment using the KR method, with the sulfur content in the molten iron controlled at 0.001%, low-sulfur scrap steel used in the converter, RH vacuum treatment, and addition of aluminum particles to adjust the Al content, with the Al element controlled above the upper limit to ensure the content after Al loss in the casting process, and a vacuum degassing time of 5.8 min.

[0073] Step b: Continuous casting with full protection against oxidation, using roll-type electromagnetic stirring to ensure an equiaxed crystal ratio of not less than 50%, a withdrawal speed of 0.93 m / min, and a slab thickness of 230 mm. C: 0.0027%, Si: 2.58%, Mn: 0.52%, P: 0.017%, S: 0.001%, Als: 0.49%, N: 0.0019%, O: 0.0016%, Ti: 0.0018%.

[0074] Step c: Hot charging of the slab into the walking beam furnace, a charging temperature of 402°C, a heating temperature of 1145°C, and a soaking time of 42 min.

[0075] Step d: rough rolling first pass reduction 53 mm, intermediate billet thickness 36 mm, finishing rolling first pass reduction 39.5%, last pass reduction 12.5%, finish rolling temperature 865°C, coiling temperature 636°C, hot rolling gauge 1.8 mm.

[0076] Step e: normalizing by rapidly heating to 800°C, holding temperature 938°C for 1.3 min.

[0077] Step f: cold rolling to 0.35 mm by 5 passes.

[0078] Step g: annealing in a continuous annealing furnace, annealing holding temperature 935°C for 35 s.

[0079] Step h: applying an insulation layer using an environmentally friendly coating, coating thickness 3.2 g / m 2 .

[0080] Comparative Example 1:

[0081] Step a: desulfurization treatment using the KR method, controlling the sulfur content in the molten iron to 0.002%, using low-sulfur scrap steel in the converter, RH vacuum treatment, adding aluminum particles to adjust the Al content, controlling the Al element to be above the upper limit to ensure the content after Al loss in the casting process, vacuum degassing time 5.7 min.

[0082] Step b: non-oxidizing casting using roll-type electromagnetic stirring to ensure an equiaxed crystal rate of not less than 50%, casting speed 0.90 m / min, slab thickness 230 mm. C: 0.0028%, Si: 2.52%, Mn: 0.51%, P: 0.016%, S: 0.002%, Als: 0.53%, N: 0.0021%, O: 0.0017%, Ti: 0.0018%.

[0083] Step c: hot charging the slab into the walking beam furnace, charging temperature 411°C, heating temperature 1143°C, soaking holding time 45 min.

[0084] Step d: rough rolling first pass reduction 54 mm, intermediate billet thickness 36 mm, finishing rolling first pass reduction 39.2%, last pass reduction 12.8%, finish rolling temperature 863°C, coiling temperature 632°C, hot rolling gauge 2.0 mm.

[0085] Step e: cold rolling to 0.35 mm by a cold rolling mill.

[0086] Step f: annealing in a continuous annealing furnace, annealing holding temperature 936°C for 45 s.

[0087] Step g: applying an insulation layer using an environmentally friendly coating, coating thickness 3.4 g / m 2.

[0088] As shown in Table 1, the magnetic properties of the high-grade thin-gauge non-oriented silicon steel 35W360 of Examples 1-3 and the comparative example, the iron loss of Examples 1-3 is reduced by a maximum of 0.047 W / kg compared with Comparative Example 1, the magnetic steel is obviously improved, and the improvement is 0.018-0.024 T, indicating that the process of Examples 1-3 is more conducive to producing high-grade non-oriented silicon steel.

[0089] Table 1: Magnetic properties of each example

[0090] State Iron loss W / kg Magnetic induction T Example 1 2.822 1.691 Example 2 2.776 1.685 Example 3 2.768 1.689 Comparative Example 1 2.815 1.667

[0091] The above-described examples only describe the preferred modes of the present application, and do not limit the scope of the present application. Without departing from the design spirit of the present application, various modifications and improvements to the technical solutions of the present application made by those of ordinary skill in the art shall fall within the protection scope determined by the claims of the present application.

Claims

1. A method for producing a high-grade thin-gauge non-oriented silicon steel 35W360, characterized by, Comprise: KR desulfurization treatment is used to control the sulfur content in molten iron at ≤0.002%; low-sulfur scrap steel is used in converter smelting; RH is used for deep decarburization treatment, and aluminum particles are added to match Al, and the pure degassing time is ensured to be not less than 5 min; The whole continuous casting process is protected from oxidation and casting, electromagnetic stirring is used to ensure that the equiaxed crystal rate of the casting blank is not less than 50%, and a small amount of columnar crystals are generated, and the slab thickness is 230 mm; The slab is hot-charged into the progressive heating furnace, the charging temperature is 350-500℃, the heating temperature is 1130-1155℃, the soaking time in the soaking section is 30-45 min, and the solid solution of as little precipitates as possible is ensured, and as little fine precipitates as possible will be generated during hot rolling; In order to break the columnar crystals as much as possible, the first pass reduction of coarse rolling is not less than 50 mm, the intermediate blank thickness is 36 mm, the first pass reduction of finish rolling is 40%, the last pass reduction is 12%, the final rolling temperature is 845-870℃, the coiling temperature is 620-650℃, and the hot rolling specification is 1.8-2.0 mm; The normalizing soaking temperature is 930-940℃, the soaking time is 1.2-1.5 min, the deformed structure in the center of the hot rolling is ensured to recrystallize, and more deformation bands will be generated during cold rolling; After 5 passes of cold rolling to a thickness of 0.35 mm, the total cold rolling reduction is controlled at 78-82%, and the generated {111} texture is less and weak; The continuous annealing soaking temperature is 930-940℃, the soaking time is 30-40 s, the steel strip reaches the annealing temperature before the annealing soaking section, the grains begin to recrystallize, the grains grow during the soaking process, and the iron loss is reduced; Coating thickness 3.2-3.3 g / m 2 ; The final 0.35 mm thin specification high-grade non-oriented silicon steel meeting the magnetic performance requirements is prepared; the iron loss reaches below 2.8 W / kg, and the magnetic induction reaches above 1.68 T; The mass percentage chemical composition: C: <0.0030%, Si: 2.30-2.70%, Mn: 0.35-0.60%, P: <0.020%, S: <0.003%, Als: 0.45-0.65%, N: <0.0030%, O: <0.0020%, Ti: <0.0025%, and the rest is Fe and unavoidable inclusions, and the total mass fraction is 100%.

2. The production method according to claim 1, characterized by, Specifically includes the following steps: Step a: KR desulfurization treatment is used to control the sulfur content in molten iron at 0.002%, low-sulfur scrap steel is used in converter smelting, RH vacuum treatment is used, Al particles are added to match Al, the Al element is controlled above the limit to ensure the content after Al loss in the casting machine process, and the vacuum degassing time is 6 min; Step b: The whole continuous casting process is protected from oxidation and casting, roll-type electromagnetic stirring is used to ensure that the equiaxed crystal rate is not less than 50%, the casting speed is 0.90 m / min, and the slab thickness is 230 mm; The mass percentage chemical composition: C: 0.0030%, Si: 2.55%, Mn: 0.48%, P: 0.018%, S: 0.002%, Als: 0.51%, N: 0.0022%, O: 0.0018%, Ti: 0.0020%, and the balance is Fe and impurities; Step c: the slab is hot charged into the walking beam furnace, the charging temperature is 385 DEG C, the heating temperature is 1142 DEG C, and the soaking time is 38 min; Step d: the rough rolling first pass reduction is 55 mm, the intermediate blank thickness is 36 mm, the first pass reduction of the finishing rolling is 39%, the last pass reduction is 11.8%, the finish rolling temperature is 856 DEG C, the coiling temperature is 628 DEG C, and the hot rolling specification is 1.8 mm; Step e: the temperature is rapidly increased to about 800 DEG C during normalizing, the temperature in the holding section is 935 DEG C, and the holding time is 1.5 min; Step f: the cold rolling is performed for 5 passes to 0.35 mm; Step g: annealing is performed in a continuous annealing furnace, the annealing holding temperature is 932 DEG C, and the holding time is 38 s; Step h: Insulation layer is coated with an environmentally friendly coating, coating thickness 3.3 g / m 2 .

3. The preparation method according to claim 1, characterized in that, Specifically, the following steps are included: Step a: KR method desulfurization treatment is adopted, the sulfur content in the molten iron is controlled to be 0.001%, low-sulfur scrap steel is used in the converter, RH vacuum treatment is adopted, and aluminum particles are added to configure Al, the Al element is controlled to be above the upper limit to ensure the content after Al loss in the casting machine process, and the vacuum degassing time is 5.5 min; Step b: full-process protection non-oxidation casting is used in continuous casting, roller electromagnetic stirring is used to ensure that the equiaxed crystal rate is not less than 50%, the drawing speed is 0.92 m / min, and the slab thickness is 230 mm; The mass percentage chemical composition is: C: 0.0028%, Si: 2.48%, Mn: 0.52%, P: 0.018%, S: 0.001%, Als: 0.55%, N: 0.0020%, O: 0.0018%, Ti: 0.0019%, and the balance is Fe and impurities; Step c: the slab is hot charged into the walking beam furnace, the charging temperature is 392 DEG C, the heating temperature is 1143 DEG C, and the soaking time is 41 min; Step d: the rough rolling first pass reduction is 52 mm, the intermediate blank thickness is 36 mm, the first pass reduction of the finishing rolling is 39.2%, the last pass reduction is 12.3%, the finish rolling temperature is 863 DEG C, the coiling temperature is 633 DEG C, and the hot rolling specification is 2.0 mm; Step e: the temperature is rapidly increased to about 800 DEG C during normalizing, the temperature in the holding section is 931 DEG C, and the holding time is 1.4 min; Step f: the cold rolling is performed for 5 passes to 0.35 mm; Step g: annealing is performed in a continuous annealing furnace, the annealing holding temperature is 935 DEG C, and the holding time is 36 s; Step h: Insulation layer is coated with an environmentally friendly coating, coating thickness 3.2 g / m 2 .

4. The method of claim 1, wherein, Specifically, the following steps are included: Step a: KR method desulfurization treatment is adopted, the sulfur content in the molten iron is controlled to be 0.001%, low-sulfur scrap steel is used in the converter, RH vacuum treatment is adopted, and aluminum particles are added to configure Al, the Al element is controlled to be above the upper limit to ensure the content after Al loss in the casting machine process, and the vacuum degassing time is 5.8 min; Step b: full-process protection non-oxidation casting is used in continuous casting, roller electromagnetic stirring is used to ensure that the equiaxed crystal rate is not less than 50%, the drawing speed is 0.93 m / min, and the slab thickness is 230 mm; The mass percentage chemical composition is: C: 0.0027%, Si: 2.58%, Mn: 0.52%, P: 0.017%, S: 0.001%, Als: 0.49%, N: 0.0019%, O: 0.0016%, Ti: 0.0018%, and the balance is Fe and impurities; Step c: slab hot charging into the walking beam furnace, charging temperature 402°C, heating temperature 1145°C, soaking time 42 min; Step d: rough rolling first pass reduction 53 mm, intermediate slab thickness 36 mm, finishing rolling first pass reduction rate 39.5%, last pass reduction rate 12.5%, finish rolling temperature 865°C, coiling temperature 636°C, hot rolling specification 1.8 mm; Step e: normalizing by rapidly heating to about 800°C, holding temperature 938°C, holding time 1.3 min; Step f: cold rolling to 0.35 mm by 5 passes; Step g: annealing in a continuous annealing furnace, annealing holding temperature 935°C, holding time 35 s; Step h: Insulation layer is coated with an environmentally friendly coating, coating thickness 3.2 g / m 2 .

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