Method for producing non-oriented silicon steel based on thin-strip cast rolling

Abstract

The invention belongs to the technical field of non-oriented electrical steel manufacturing, and relates to a method for producing non-oriented silicon steel based on thin-strip cast rolling. The low-silicon and aluminum-free component design is adopted, the hot-rolled thin substrate is directly obtained through thin strip cast rolling, casting blank continuous casting and casting blank heating are omitted, the hot rolling reduction is greatly reduced, it is avoided that unfavorable textures of alpha and gamma components in the finished non-oriented silicon steel are remarkably improved, and the high magnetic induction of the finished product is guaranteed; after acid pickling and cold rolling, grain growth is promoted by means of high-temperature cover annealing, and low iron loss of a finished product is guaranteed; the high-magnetic-induction low-iron-loss non-oriented silicon steel with the thickness specification of 0.50 mm is obtained, the grain size of a finished product is 80-100 microns, the iron loss P1.5 / 50 is smaller than or equal to 4.0 W / kg, and the magnetic induction B5000 is larger than or equal to 1.76 T.

Description

Technical Field

[0001] The invention belongs to the technical field of thin strip casting and rolling, and relates to a method for producing non-oriented silicon steel based on thin strip casting and rolling. Background Art

[0002] Non-oriented silicon steel is an important soft magnetic material, mainly used to manufacture the iron cores of various motors. Therefore, improving the magnetic properties of low-silicon non-oriented silicon steel can effectively improve motor efficiency, save energy and reduce consumption, and protect the environment.

[0003] The magnetic properties of non-oriented silicon steel primarily consist of iron loss and magnetic induction. Reducing iron loss can lower motor energy consumption and improve energy conversion efficiency. Improving magnetic induction increases the core's power density, improving operating efficiency. It also reduces the excitation current, lowering copper loss and iron loss, and also helps reduce the core's volume, saving material. The magnetic properties of non-oriented silicon steel directly impact the motor's energy efficiency rating, practicality, and reliability, making improving the steel's magnetic properties particularly important.

[0004] To improve the energy efficiency of motors, non-oriented silicon steel is required to have lower iron loss and higher magnetic induction. The {100} orientation is the most ideal texture type. Because {100}<0vw> is the preferred orientation during the solidification process, it is usually present in large quantities in continuous casting billets. When preparing non-oriented silicon steel through traditional processes, due to the thick billet thickness, hot rolling and cold rolling with a high compression ratio, the α and γ components in the non-oriented silicon steel texture are significantly increased, including {111} <110> 、{111} <112> 、{112} <100> components, forming a stable texture. As a result, the as-cast structure and texture are difficult to retain, and the inheritance of the solidified structure and {100}<0vw> texture is minimized. When preparing non-oriented silicon steel through traditional processes, the structure, texture and magnetic properties of non-oriented silicon steel are regulated by controlling the chemical composition, rolling process and annealing parameters. However, the overall effect is manifested as a reduction in the unfavorable α and γ components in the texture, which cannot change the fact that the solidification texture is severely damaged due to high reduction rate rolling. In fact, traditional processes are essentially unable to achieve the coexistence of high magnetic induction and low iron loss, and can only be adjusted to a limited extent. This is also the fundamental reason why the higher the grade of traditional processes (representing lower iron loss), the lower the magnetic induction. Summary of the Invention

[0005] To address the aforementioned issues with conventional non-oriented silicon steel production processes, the present invention provides a non-oriented silicon steel based on thin strip casting and a production method thereof. This process employs a low-silicon, aluminum-free design to directly produce a hot-rolled thin substrate through thin strip casting, eliminating the need for continuous casting and heating of the ingot and significantly reducing hot rolling reduction. This significantly enhances the unfavorable textures of the α and γ components in the finished non-oriented silicon steel, ensuring high magnetic induction in the finished product. Following pickling and cold rolling, high-temperature hood annealing is used to promote grain growth and ensure low iron loss in the finished product. The result is a non-oriented silicon steel with a thickness of 0.50 mm, high magnetic induction, and low iron loss.

[0006] The present invention specifically adopts the following technical solutions:

[0007] According to a first aspect of the present invention, a method for producing non-oriented silicon steel based on thin strip casting is provided, the method comprising the following steps:

[0008] 1) Molten steel smelting

[0009] Molten steel is obtained according to the following composition by mass percentage:

[0010] C≤0.0030%, S≤0.0030%, Si: 1.00~1.50%, Mn: 0.20~0.60%,

[0011] P≤0.03%, Al: ≤0.003%, Nb≤0.003%, V≤0.003%,

[0012] Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, Cu≤0.02%, N≤0.0020%, the rest is Fe and unavoidable inclusions;

[0013] 2) Thin strip casting

[0014] Twin-roll casting was used for continuous casting to obtain a cast strip with a thickness of 1.80±0.20 mm.

[0015] The cast strip is hot rolled into a hot rolled thin strip with a thickness of 1.00 to 1.60 mm in one pass.

[0016] Control the finishing temperature at 800-850℃ and the coiling temperature at 500-550℃.

[0017] 3) Pickling + cold rolling

[0018] Use hydrochloric acid four-stage pickling, the concentration of the first-level acid solution is 30-50g / L, the concentration of the second-level acid solution is 70-90g / L, the concentration of the third-level acid solution is 100-120g / L, the concentration of the fourth-level acid solution is 140-160g / L, and the Fe content in the first-level acid solution is 20-30g / L. 2+ Concentration ≤130g / L, Fe in 2nd grade acid solution 2+Concentration ≤100g / L, Fe in grade 3 acid solution 2+ Concentration ≤85g / L, Fe in 4-grade acid solution 2+ Concentration ≤ 50g / L, acid solution temperature 75-85℃; rinse water temperature 45-55℃, pickling and rinsing speeds controlled at 150-200mpm, pickling time not less than 45-60s,

[0019] The cold rolling adopts a single-stand rolling mill, and after 2 to 4 passes, a chilled coil with a thickness of 0.50 mm is obtained.

[0020] 4) High temperature hood annealing + coating + finishing

[0021] In the high-temperature bell-type annealing process, the annealing temperature is controlled at T and kept at this temperature for 120 to 150 minutes, wherein:

[0022] T=(Ar1-40)~(Ar1-20)℃,

[0023] Ar1 is the γ / α phase transition temperature, unit is °C;

[0024] The calculation formula of Ar1 is:

[0025] Ar1=872℃+1000(11*[Si]-14*[Mn]+21*[Al]), where [Si], [Mn], and [Al] are

[0026] are the mass percentages of Si, Mn and Al respectively.

[0027] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in the molten steel smelting process, 60-80% molten iron + 20-40% scrap steel are used for converter steelmaking, and the converter end point C is: 0.020-0.050%, S≤0.0025%, and P≤0.03%.

[0028] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in the molten steel smelting process, 60-80% molten iron + 20-40% scrap steel are used for converter steelmaking, and the converter end point C is 0.020-0.050%, S is ≤0.0025%, and P is ≤0.03%.

[0029] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in the molten steel smelting process, molten steel is obtained according to the following mass percentage components:

[0030] C≤0.0030%, S≤0.0030%, Si:1.20~1.30%, Mn:0.20~0.40%, P≤0.03%, Al:≤0.003%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, Cu≤0.02%, N≤0.0020%, others are Fe and unavoidable inclusions.

[0031] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in the thin strip casting and rolling process, the starting pouring temperature of the molten steel is 1565-1575°C, the thickness of the cast strip is 1.80±0.20mm, and the continuous casting speed is 60-70m / min.

[0032] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in the thin strip casting and rolling process, the cast strip enters the rolling mill through a hot box under the protection of inert gas, and is hot-rolled into a hot-rolled thin strip with a thickness of 1.00 to 1.60 mm in one pass.

[0033] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, the pickling + cold rolling process adopts four-stage hydrochloric acid pickling, the concentration of the first-stage acid solution is 30-50g / L, the concentration of the second-stage acid solution is 70-90g / L, the concentration of the third-stage acid solution is 100-120g / L, the concentration of the fourth-stage acid solution is 140-160g / L, and the Fe content in the first-stage acid solution is 0.1%. 2+ Concentration ≤130g / L, Fe in 2nd grade acid solution 2+ Concentration ≤100g / L, Fe in grade 3 acid solution 2+ Concentration ≤85g / L, Fe in 4-grade acid solution 2+ Concentration ≤50g / L, acid solution temperature 75~85℃; rinse water temperature 45~55℃, pickling and rinsing speeds controlled at 150~200mpm, pickling time not less than 45~60s.

[0034] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, the pickling + cold rolling process uses a single-stand rolling mill, and a chilled coil with a thickness of 0.50 mm is obtained through 2 to 4 rolling passes.

[0035] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, high-temperature hood annealing + coating + finishing steps are performed, and the high-temperature hood annealing is carried out in a pure N2 atmosphere; after the insulation is completed, cooling is carried out at a rate of 2 to 10°C / min, and after cooling to 300°C, it is cooled to 100°C with the furnace, the steel coil is taken out, and finally coating and finishing are performed to obtain a non-oriented silicon steel product.

[0036] According to a second aspect of the present invention, a non-oriented silicon steel is provided, wherein the non-oriented silicon steel is produced according to the above method, wherein the thickness of the non-oriented silicon steel is 0.50 mm, the finished product grain size is 80-100 μm, and the iron loss P is 0.50 mm. 1.5 / 50 ≤4.0W / kg, magnetic induction B 5000 ≥1.76T.

[0037] According to a third aspect of the present invention, there is provided a method for producing non-oriented silicon steel based on thin strip casting, comprising the following steps:

[0038] (1) After converter steelmaking, vacuum smelting and alloying, molten steel with qualified composition is obtained, which is as follows by mass percentage:

[0039] C≤0.0030%, S≤0.0030%, Si:1.00~1.50%, Mn:0.20~0.60%, P≤0.03%, Al:≤0.003%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, Cu≤0.02%, N≤0.0020%, others are Fe and unavoidable inclusions;

[0040] (2) Continuously casting the strip using a twin-roll casting process to obtain a cast strip having a thickness of 1.80±0.20 mm at a casting speed of 60-70 m / min; the cast strip is hot-rolled in one pass into a hot-rolled thin strip having a thickness of 1.00-1.60 mm, with a final rolling temperature of 800-850°C and a coiling temperature of 500-550°C;

[0041] (3) the hot rolled coil obtained by strip casting is pickled and rolled in a single stand mill in sequence, and a chilled coil with a thickness of 0.50 mm is obtained after 2 to 4 rolling passes;

[0042] (4) High temperature hood annealing + coating + finishing:

[0043] The chilled coil is subjected to high-temperature bell annealing in a pure N2 atmosphere, the annealing temperature is controlled to be T, and the temperature is kept at this temperature for 120 to 150 minutes, wherein:

[0044] T = (Ar1-40) ~ (Ar1-20) ° C, Ar1 is the γ / α phase transition temperature, unit: ° C;

[0045] The calculation formula of Ar1 is:

[0046] Ar1=872℃+1000(11*[Si]-14*[Mn]+21*[Al]), where [Si], [Mn], and [Al] are

[0047] are the mass percentages of Si, Mn and Al respectively.

[0048] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in step 1), 60-80% molten iron + 20-40% scrap steel are used for converter steelmaking in molten steel, and the converter end point C is 0.020-0.050%, S≤0.0025%, and P≤0.03%.

[0049] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in step 1), the qualified molten steel composition is as follows by mass percentage: C≤0.0030%, S≤0.0030%, Si: 1.20~1.30%, Mn: 0.20~0.40%, P≤0.03%, Al: ≤0.003%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, Cu≤0.02%, N≤0.0020%, and the others are Fe and unavoidable inclusions.

[0050] According to the method for producing non-oriented silicon steel based on thin strip casting of the present invention, preferably, in step 2), the starting pouring temperature of the thin strip casting molten steel is 1565-1575°C, the thickness of the cast strip is 1.80±0.20mm, and the continuous casting speed is 60-70m / min.

[0051] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in step 2), the cast strip enters the rolling mill through a hot box under the protection of inert gas and is hot-rolled into a hot-rolled thin strip with a thickness of 1.00 to 1.60 mm in one pass.

[0052] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in step 3), four-stage hydrochloric acid pickling is adopted, the concentration of the first-stage acid solution is 30-50 g / L, the concentration of the second-stage acid solution is 70-90 g / L, the concentration of the third-stage acid solution is 100-120 g / L, the concentration of the fourth-stage acid solution is 140-160 g / L, and the Fe content in the first-stage acid solution is 0.1%. 2+ Concentration ≤130g / L, Fe in 2nd grade acid solution 2+ Concentration ≤100g / L, Fe in grade 3 acid solution 2+ Concentration ≤85g / L, Fe in 4-grade acid solution 2+ Concentration ≤50g / L, acid solution temperature 75~85℃; rinse water temperature 45~55℃, pickling and rinsing speeds controlled at 150~200mpm, pickling time not less than 45~60s.

[0053] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in step 3), cold rolling is carried out using a single-stand rolling mill, and a chilled coil with a thickness of 0.50 mm is obtained through 2 to 4 rolling passes.

[0054] According to the method for producing non-oriented silicon steel based on thin strip casting and rolling of the present invention, preferably, in step 3), the first pass reduction rate of the single-stand rolling mill is controlled to be 30-35%, and the last pass reduction rate is not less than 20%.

[0055] According to a fourth aspect of the present invention, there is provided a non-oriented silicon steel produced by the aforementioned method, wherein the thickness of the non-oriented silicon steel is 0.50 mm and the finished grain size is 80-100 μm.

[0056] According to the non-oriented silicon steel of the present invention, the iron loss P of the non-oriented silicon steel is 1.5 / 50 ≤4.0W / kg, magnetic induction B 5000 ≥1.76T.

[0057] The role of each element in the present invention is analyzed as follows:

[0058] C, S, N: C, S, and N are harmful elements in non-oriented silicon steel, which lead to increased iron loss and reduced magnetic induction. In order to meet the requirements of low iron loss and high magnetic induction of the non-oriented silicon steel based on thin strip casting, C≤0.0030%, S≤0.0030%, and N≤0.0020%;

[0059] Si, Al, Mn: Si and Al can increase the resistivity of the steel plate and thus reduce the iron loss of non-oriented silicon steel; Mn forms MnS with S, which affects grain growth but avoids the formation of low-melting-point FeS at the grain boundaries to avoid hot brittleness. Therefore, when preparing non-oriented silicon steel in the traditional process, the Si+Al+Mn design is adopted. However, in the thin strip casting and rolling process of the present invention, the Al2O3 inclusions formed by Al during the steelmaking process will gradually accumulate and form nodules on the side sealing plates of the molten pool. Once the nodules are washed down by the steel flow and enter the casting rollers, it will cause the continuous casting strip to break. Therefore, the present invention strictly controls Al≤0.003%; Si can reduce the iron loss of non-oriented silicon steel, but it will also reduce the magnetic induction. Taking into account the thickness specifications of the finished product and the simultaneous low iron loss and high magnetic induction, the Si content is controlled between 1.00 and 1.50%, and the Mn content is controlled between 0.20 and 0.60%.

[0060] Nb, V, Ti, Cr, Ni, Cu: Nb, V, Ti, Cr, Ni, and Cu in non-oriented silicon steel will increase iron loss and reduce magnetic induction. Therefore, control Nb≤0.003%, V≤0.003%, Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, and Cu≤0.02%;

[0061] Phosphorus (P) is a residual element that, in conventional processes, can segregate in the core of the ingot, affecting rollability and microstructure uniformity in the finished product. Therefore, P is typically controlled to 0.015% or less, significantly increasing steelmaking costs. However, in the thin strip casting and rolling process of the present invention, P does not segregate due to the high cooling rate of the strip at 1000°C / s. Therefore, the present invention relaxes the P control standard to 0.03% or less, reducing steelmaking costs.

[0062] The core of the present invention is to adopt a low-silicon and aluminum-free composition design, and through the thin strip casting and rolling process, significantly reduce the hot rolling reduction, avoid the significant improvement of the unfavorable texture of α and γ components in the finished non-oriented silicon steel, and ensure the high magnetic induction of the finished product;

[0063] After pickling and cold rolling, high-temperature hood annealing is used to promote grain growth and ensure low iron loss in the finished product; high magnetic induction, low iron loss non-oriented silicon steel with a thickness of 0.50mm is obtained.

[0064] Beneficial technical effects

[0065] Compared with the prior art, the technical concept and corresponding technical solutions of the present invention can at least achieve the following beneficial technical effects:

[0066] (1) The molten steel is directly cast into a strip with a thickness of 1.80±0.20 mm by two rotating steel rollers. Compared with the conventional process using 220 mm ingot, the subsequent hot rolling and cold rolling reduction is greatly reduced, and the high reduction ratio hot rolling + cold rolling is avoided, which causes a significant increase in the α and γ components in the non-oriented silicon steel texture, including {111} <110> 、{111} <112> 、{112} <100> components; thereby increasing the proportion of the ideal {100}<0vw> texture and improving the magnetic induction of the finished product.

[0067] (2) Hot rolled coils with a thickness of 1.00 to 1.60 mm are directly obtained by thin strip casting. Compared with the traditional process of low-silicon non-oriented silicon steel using 2.50 to 2.75 mm hot rolled coils to produce 0.50 mm thick cold rolled coils through five-stand continuous rolling, cold rolled coils with a thickness of 0.50 mm can be directly obtained by 2 to 4 passes of rolling using a single-stand rolling mill, thereby reducing the cost of cold rolling.

[0068] (3) By controlling the hot rolling finishing temperature to 800-850℃ and the coiling temperature to 500-550℃, low-temperature rolling and low-temperature coiling are achieved, the hot-rolled grain size is refined, and conditions are created for obtaining large grains by subsequent high-temperature hood annealing.

[0069] (4) Precisely control the high-temperature hood annealing process, control the annealing temperature to T, and keep it at this temperature for 120 to 150 minutes. Wherein T = (Ar1-40) to (Ar1-20) ° C, Ar1 is the γ / α phase transformation temperature, unit is ° C. Precisely control the temperature to ensure that the annealing is completed in the high-temperature ferrite region of the non-oriented silicon steel; long-term heat preservation promotes the growth of fine MnS precipitates formed in the non-oriented silicon steel due to the high cooling rate of 1000 ° C / s in the casting strip, reducing its hindering effect on grain growth; and finally achieves the non-oriented silicon steel finished product grain size of 80 to 100 μm.

[0070] (5) The present invention adopts a twin-roller thin strip continuous casting method, which omits hot rolling heating, hot rolling rough rolling, normalizing and other processes compared with conventional processes. It is an energy-saving and environmentally friendly short-process production technology. DETAILED DESCRIPTION

[0071] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0072] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

[0073] The following are embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments that can be obtained by ordinary technicians in this field without making any creative work are within the scope of protection of the present invention.

[0074] The following four examples further illustrate the beneficial effects of this embodiment. Of course, these four examples are only a part of the many variations of the present invention, not all of them. The four examples each provide a non-oriented silicon steel based on thin strip casting, and the production method thereof is as follows:

[0075] (1) Molten steel smelting: In Examples 1 to 4, molten steel smelting was performed by using molten iron + scrap steel for converter steelmaking. The ratio of molten iron to scrap steel, and the mass percentages of C, S, and P at the converter end point in Examples 1 to 4 are shown in Table 1.

[0076] Table 1 The ratio of molten iron to scrap steel in Examples 1 to 4, and the mass percentage of C, S, and P at the converter end point

[0077]

[0078]

[0079] Then, after vacuum smelting and alloying, molten steel with qualified composition is obtained. The chemical compositions of Examples 1 to 4 are shown in Table 2 in terms of mass percentage.

[0080] Table 2 Chemical composition of Examples 1 to 4 (in mass percentage)

[0081]

[0082] (2) Strip Casting: Continuous casting is performed using a twin-roll casting process. Molten steel is poured through a tundish into a molten pool consisting of rotating steel rolls and side closure plates. The molten steel rapidly solidifies and forms upon contact with the crystallizing roll surfaces of the steel rolls, producing a cast strip. The cast strip then passes through a hot box under inert gas protection and enters a rolling mill, where it is hot-rolled in a single pass into a hot-rolled strip. The corresponding pouring temperature, continuous casting speed, cast strip thickness, reduction ratio, hot-rolled strip thickness, final rolling temperature, and coiling temperature for Examples 1-4 are shown in Table 3.

[0083] Table 3 Parameters of pouring temperature, continuous casting speed, etc. of Examples 1 to 4

[0084]

[0085] (3) Pickling + Cold Rolling: In Examples 1 to 4, the hot-rolled thin strip obtained by strip casting in step 2 was pickled and rolled on a single-stand rolling mill in sequence to obtain a chilled coil with a thickness of 0.50 mm; a four-stage hydrochloric acid pickling was used, with the concentration of the first-stage acid solution being 40 g / L, the concentration of the second-stage acid solution being 82 g / L, the concentration of the third-stage acid solution being 113 g / L, and the concentration of the fourth-stage acid solution being 148 g / L. The concentration of Fe in the first-stage acid solution was 1.3 g / L. 2+ Concentration ≤130g / L, Fe in 2nd grade acid solution 2+ Concentration ≤100g / L, Fe in grade 3 acid solution 2+ Concentration ≤85g / L, Fe in 4-grade acid solution 2+ The concentration is ≤50g / L, the acid solution temperature is 80°C; the rinse water temperature is 50°C, the pickling and rinsing speeds are controlled at 157mpm, and the pickling time is 55s. Example 1 cold rolling uses two passes, with pass reductions of 34.5% and 30.5%, respectively; Example 2 cold rolling uses three passes, with pass reductions of 32.0%, 33.3%, and 28.6%, respectively; Example 3 cold rolling uses three passes, with pass reductions of 32.0%, 23.5%, and 23.1%, respectively; Example 4 cold rolling uses three passes, with pass reductions of 32.1%, 31.6%, and 23.1%, respectively.

[0086] (4) High-temperature bell annealing + coating + finishing: In Examples 1-4, the chilled coils from Step 3 were subjected to high-temperature bell annealing in a pure N2 atmosphere. The annealing temperature was controlled at T and the coils were kept at this temperature. After the holding temperature was completed, the coils were cooled at a rate of 5°C / min to 300°C, then cooled to 100°C in the furnace, and the coils were removed. Finally, the non-oriented silicon steel products were obtained after coating and finishing.

[0087] Annealing temperature, holding time, finished product grain size, iron loss and magnetic induction of Examples 1 to 4, and γ / α phase transition temperature Ar1 of Examples 1 to 4 are shown in Table 4.

[0088] Table 4 Annealing temperature, holding time and other parameters of Examples 1 to 4

[0089]

[0090] The above description is only a specific embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, they can make several improvements and modifications without departing from the principles of the present invention. These improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing non-oriented silicon steel based on thin strip casting, characterized in that: The method comprises the following steps: 1) Molten steel smelting Molten steel is obtained according to the following composition by mass percentage: C≤0.0030%, S≤0.0030%, Si: 1.00~1.50%, Mn: 0.20~0.60%, P≤0.03%, Al: ≤0.003%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, Cu≤0.02%, N≤0.0020%, the rest is Fe and unavoidable inclusions; 2) Thin strip casting Twin-roll casting was used for continuous casting to obtain a cast strip with a thickness of 1.80±0.20 mm. The cast strip is hot rolled into a hot rolled thin strip with a thickness of 1.00 to 1.60 mm in one pass. Control the finishing temperature at 800-850℃ and the coiling temperature at 500-550℃. 3) Pickling + cold rolling Use hydrochloric acid four-stage pickling, the concentration of the first-level acid solution is 30-50g / L, the concentration of the second-level acid solution is 70-90g / L, the concentration of the third-level acid solution is 100-120g / L, the concentration of the fourth-level acid solution is 140-160g / L, and the Fe content in the first-level acid solution is 20-30g / L. 2+ Concentration ≤130g / L, Fe in 2nd grade acid solution 2+ Concentration ≤100g / L, Fe in grade 3 acid solution 2+ Concentration ≤85g / L, Fe in 4-grade acid solution 2+ Concentration ≤ 50g / L, acid temperature 75-85℃; rinse water temperature 45-55℃, pickling and rinsing speeds controlled at 150-200mpm, pickling time not less than 45-60s, The cold rolling adopts a single-stand rolling mill, and after 2 to 4 passes of rolling, a chilled coil with a thickness of 0.50 mm is obtained. 4) High temperature hood annealing + coating + finishing In the high-temperature bell-type annealing process, the annealing temperature is controlled at T and kept at this temperature for 120 to 150 minutes, wherein: T=(Ar1-40)~(Ar1-20)℃, Ar1 is the γ / α phase transition temperature, unit is °C; The calculation formula of Ar1 is: Ar1=872℃+1000(11*[Si]-14*[Mn]+21*[Al]), where [Si], [Mn] and [Al] are the mass percentages of Si, Mn and Al respectively.

2. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 1, characterized in that: The molten steel smelting process uses 60-80% molten iron + 20-40% scrap steel for converter steelmaking, and the converter end point C is: 0.020-0.050%, S≤0.0025%, and P≤0.03%.

3. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 1, characterized in that: The molten steel smelting process uses 60-80% molten iron + 20-40% scrap steel for converter steelmaking, and the converter end point C is 0.020-0.050%, S is ≤0.0025%, and P is ≤0.03%.

4. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 1, characterized in that: The molten steel smelting process obtains molten steel according to the following mass percentage components: C≤0.0030%, S≤0.0030%, Si:1.20~1.30%, Mn:0.20~0.40%, P≤0.03%, Al:≤0.003%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, Cu≤0.02%, N≤0.0020%, others are Fe and unavoidable inclusions.

5. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 1, characterized in that: In the thin strip casting and rolling process, the starting pouring temperature of the molten steel is 1565~1575℃, the thickness of the cast strip is 1.80±0.20mm, and the continuous casting speed is 60~70m / min.

6. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 1, characterized in that: In the thin strip casting and rolling process, the cast strip passes through a hot box under the protection of inert gas and enters the rolling mill, and is hot-rolled into a hot-rolled thin strip with a thickness of 1.00 to 1.60 mm in one pass.

7. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 1, characterized in that: Pickling + cold rolling process, using hydrochloric acid four-stage pickling, the concentration of the first-level acid solution is 30-50g / L, the concentration of the second-level acid solution is 70-90g / L, the concentration of the third-level acid solution is 100-120g / L, the concentration of the fourth-level acid solution is 140-160g / L, the concentration of Fe in the first-level acid solution is 20-30g / L, and the concentration of Fe in the fourth-level acid solution is 100-120g / L. 2+ Concentration ≤130g / L, Fe in 2nd grade acid solution 2+ Concentration ≤100g / L, Fe in grade 3 acid solution 2+ Concentration ≤85g / L, Fe in 4-grade acid solution 2+ Concentration ≤50g / L, acid solution temperature 75~85℃; rinse water temperature 45~55℃, pickling and rinsing speeds controlled at 150~200mpm, pickling time not less than 45~60s.

8. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 1, characterized in that: Pickling + cold rolling process, cold rolling adopts a single-stand rolling mill, and after 2 to 4 passes of rolling, a chilled coil with a thickness of 0.50 mm is obtained.

9. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 1, characterized in that: High temperature hood annealing + coating + finishing process, high temperature hood annealing is carried out in a pure N2 atmosphere; after the insulation is completed, it is cooled at a rate of 2 to 10°C / min. After cooling to 300°C, it is cooled to 100°C with the furnace, the steel coil is taken out, and finally coated and finished to obtain the non-oriented silicon steel product.

10. A non-oriented silicon steel, characterized in that: The non-oriented silicon steel is produced by the method according to any one of claims 1 to 9, wherein the thickness of the non-oriented silicon steel is 0.50 mm, the finished product grain size is 80 to 100 μm, and the iron loss P is 0. 1.5 / 50 ≤4.0W / kg, magnetic induction B 5000 ≥1.76T.

11. A method for producing non-oriented silicon steel based on thin strip casting, characterized in that: The following steps are involved: (1) After converter steelmaking, vacuum smelting and alloying, molten steel with qualified composition is obtained, which is as follows by mass percentage: C≤0.0030%, S≤0.0030%, Si:1.00~1.50%, Mn:0.20~0.60%, P≤0.03%, Al:≤0.003%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, Cu≤0.02%, N≤0.0020%, others are Fe and unavoidable inclusions; (2) Continuously casting the strip using a twin-roll casting process to obtain a cast strip having a thickness of 1.80±0.20 mm at a casting speed of 60-70 m / min; the cast strip is hot-rolled in one pass into a hot-rolled thin strip having a thickness of 1.00-1.60 mm, with a final rolling temperature of 800-850°C and a coiling temperature of 500-550°C; (3) the hot rolled coil obtained by strip casting is pickled and rolled in a single stand mill in sequence, and a chilled coil with a thickness of 0.50 mm is obtained after 2 to 4 rolling passes; (4) High temperature hood annealing + coating + finishing: The chilled coil is subjected to high-temperature bell annealing in a pure N2 atmosphere, the annealing temperature is controlled to be T, and the temperature is kept at this temperature for 120 to 150 minutes, wherein: T = (Ar1-40) ~ (Ar1-20) ° C, Ar1 is the γ / α phase transition temperature, unit: ° C; The calculation formula of Ar1 is: Ar1=872℃+1000(11*[Si]-14*[Mn]+21*[Al]), where [Si], [Mn] and [Al] are the mass percentages of Si, Mn and Al respectively.

12. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 11, characterized in that: In step 1), molten steel is smelted by using 60-80% molten iron + 20-40% scrap steel for converter steelmaking, with converter end point C: 0.020-0.050%, S≤0.0025%, and P≤0.03%.

13. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 11, characterized in that: In step 1), the qualified molten steel composition is as follows by mass percentage: C≤0.0030%, S≤0.0030%, Si:1.20~1.30%, Mn:0.20~0.40%, P≤0.03%, Al:≤0.003%, Nb≤0.003%, V≤0.003%, Ti≤0.003%, Cr≤0.02%, Ni≤0.02%, Cu≤0.02%, N≤0.0020%, and the rest is Fe and unavoidable inclusions.

14. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 11, characterized in that: In step 2), the starting pouring temperature of the thin strip casting molten steel is 1565-1575° C., the thickness of the cast strip is 1.80±0.20 mm, and the continuous casting speed is 60-70 m / min.

15. The method for producing non-oriented silicon steel based on thin strip casting according to claim 11, characterized in that: In step 2), the cast strip enters the rolling mill through a hot box under the protection of inert gas and is hot-rolled into a hot-rolled thin strip with a thickness of 1.00 to 1.60 mm in one pass.

16. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 11, characterized in that: In step 3), hydrochloric acid is used for four-stage pickling, the concentration of the first-stage acid solution is 30-50 g / L, the concentration of the second-stage acid solution is 70-90 g / L, the concentration of the third-stage acid solution is 100-120 g / L, the concentration of the fourth-stage acid solution is 140-160 g / L, and the Fe content in the first-stage acid solution is 0. 2+ Concentration ≤130g / L, Fe in 2nd grade acid solution 2+ Concentration ≤100g / L, Fe in grade 3 acid solution 2+ Concentration ≤85g / L, Fe in 4-grade acid solution 2+ Concentration ≤50g / L, acid solution temperature 75~85℃; rinse water temperature 45~55℃, pickling and rinsing speeds controlled at 150~200mpm, pickling time not less than 45~60s.

17. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 11, characterized in that: In step 3), a single-stand rolling mill is used for cold rolling, and a chilled coil with a thickness of 0.50 mm is obtained through 2 to 4 rolling passes.

18. The method for producing non-oriented silicon steel based on thin strip casting and rolling according to claim 11, characterized in that: In step 3), the first-pass reduction rate of the single-stand rolling mill is controlled to be 30-35%, and the last-pass reduction rate is not less than 20%.

19. A non-oriented silicon steel, characterized by: The non-oriented silicon steel is produced by the method according to any one of claims 11 to 18, wherein the thickness of the non-oriented silicon steel is 0.50 mm, and the finished grain size is 80 to 100 μm.

20. The non-oriented silicon steel according to claim 19, characterized in that: The iron loss P of the non-oriented silicon steel 1.5 / 50 ≤4.0W / kg, magnetic induction B 5000 ≥1.76T.

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