1. The non-oriented silicon steel is characterized by comprising the following chemical components in percentage by mass: less than or equal to 0.004 percent of C, less than or equal to 0.004 percent of S, 0.8 to 1.1 percent of Si, 0.2 to 0.4 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.004 percent of Nb, less than or equal to 0.006 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.03 percent of Cu, less than or equal to 0.004 percent of N, 0.15 to 0.30 percent of Al or less than or equal to 0.02 percent of Al, and the balance of Fe and inevitable impurities; the thickness of the non-oriented silicon steel is 0.500 +/-0.005 mm, and the non-oriented silicon steel is prepared by sequentially carrying out steelmaking, casting blank, hot rolling, normalizing, acid continuous rolling, finished product annealing, cooling, coating and finishing;

sn and Sb are not added during the steelmaking process;

in the hot rolling step: heating a casting blank obtained in the casting blank process to 1060-1120 ℃, preserving heat for more than 150min, rolling the casting blank into an intermediate blank with the thickness of 40-45 mm, and performing finish rolling and coiling on the intermediate blank to obtain a hot-rolled coil plate with the thickness of 3.00 +/-0.25 mm, wherein the finish rolling initial rolling temperature is less than or equal to A_r1＝872℃+1000*(11*[Si]-14*[Mn]+21*[Al]) In the formula [ Si ]]、[Mn]、[Al]Respectively representing the mass percentages of Si, Mn and Al in the casting blank; the finish rolling temperature is not more than 820 ℃, and the coiling temperature is not more than 560 ℃;

in the normalizing process, the normalizing temperature is 850-900 ℃;

in the finished product annealing process, the production is carried out at a constant speed, and the annealing temperature is 820-880 ℃.

2. The non-oriented silicon steel of claim 1, having a core loss of P_1.5/50Less than or equal to 4.2W/kg and iron loss P of head, middle and tail_1.5/50Fluctuation less than or equal to 0.2W/kg and magnetic induction intensity B₅₀₀₀Magnetic induction B of not less than 1.72T and head, middle and tail₅₀₀₀The fluctuation is less than or equal to 0.02T.

3. The non-oriented silicon steel of claim 1, wherein the normalizing process is carried out in pure dry N₂Normalizing the mixture for 120 to 150 seconds under the atmosphere.

4. The non-oriented silicon steel of claim 1, wherein the normalizing temperature fluctuates by ± 10 ℃ during the normalizing process and is produced at a constant rate.

5. The non-oriented silicon steel of claim 1, wherein in the annealing process, the annealing time is 50 ± 5s, the annealing temperature fluctuates ± 10 ℃ and the production is performed at a constant speed.

6. A method for producing non-oriented silicon steel, characterized by comprising the steps of,

1) carrying out steel making under the condition of not adding Sn and Sb, and preparing a casting blank, wherein the casting blank comprises the following chemical components in percentage by mass: less than or equal to 0.004 percent of C, less than or equal to 0.004 percent of S, 0.8 to 1.1 percent of Si, 0.2 to 0.4 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.004 percent of Nb, less than or equal to 0.006 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.03 percent of Cu, less than or equal to 0.004 percent of N, 0.15 to 0.30 percent of Al or less than or equal to 0.02 percent of Al, and the balance of Fe and inevitable impurities;

2) heating the casting blank to 1060-1120 ℃, preserving heat for more than 150min, rolling the casting blank into an intermediate blank with the thickness of 40-45 mm, and then performing finish rolling and coiling on the intermediate blank to obtain a hot-rolled coil plate with the thickness of 3.00 +/-0.25 mm, wherein the finish rolling initial rolling temperature is less than or equal to A_r1＝872℃+1000*(11*[Si]-14*[Mn]+21*[Al]) In the formula [ Si ]]、[Mn]、[Al]Respectively representing the mass percentages of Si, Mn and Al in the casting blank; the finish rolling temperature is not more than 820 ℃, and the coiling temperature is not more than 560 ℃;

3) normalizing the hot-rolled coil and carrying out acid continuous rolling in sequence to obtain a cold-hard coil with the thickness of 0.500 +/-0.005 mm, wherein the normalizing temperature is 850-900 ℃;

4) the cold hard coil is processed in a continuous annealing furnace H₂+N₂Annealing the finished product at a constant speed in the mixed atmosphere, wherein the annealing temperature of the finished product is 820-880 ℃; and cooling, coating and finishing the annealed steel strip to obtain the non-oriented silicon steel.

7. Method for producing non-oriented silicon steel according to claim 6 characterised in that in step 3, pure dry N is used₂Normalizing the mixture for 120 to 150 seconds under the atmosphere.

8. The method for producing a non-oriented silicon steel according to claim 6, wherein in step 3, the normalizing temperature fluctuates by ± 10 ℃ and is produced at a constant rate.

9. The method for producing a non-oriented silicon steel according to claim 6, wherein in step 4, the annealing time is 50 ± 5s and the annealing temperature fluctuates ± 10 ℃ and is produced at a constant rate.

10. The method of producing a non-oriented silicon steel according to claim 6, wherein the obtained non-oriented silicon steel has an iron lossP_1.5/50Less than or equal to 4.2W/kg and iron loss P of head, middle and tail_1.5/50Fluctuation less than or equal to 0.2W/kg and magnetic induction intensity B₅₀₀₀Magnetic induction B of not less than 1.72T and head, middle and tail₅₀₀₀The fluctuation is less than or equal to 0.02T.

11. A method for producing non-oriented silicon steel, characterized by comprising the steps of,

1) carrying out steel making according to the mass percent of Si and Mn in the chemical components of 0.8-1.1% and 0.2-0.4%, wherein Sn and Sb are not added during the steel making, and preparing a casting blank;

2) heating the casting blank to 1060-1120 ℃, preserving heat for more than 150min, rolling the casting blank into an intermediate blank with the thickness of 40-45 mm, and then performing finish rolling and coiling on the intermediate blank to obtain a hot-rolled coil plate with the thickness of 3.00 +/-0.25 mm, wherein the finish rolling initial rolling temperature is less than or equal to A_r1＝872℃+1000*(11*[Si]-14*[Mn]+21*[Al]) In the formula [ Si ]]、[Mn]、[Al]Respectively representing the mass percentages of Si, Mn and Al in the casting blank; the finish rolling temperature is not more than 820 ℃, and the coiling temperature is not more than 560 ℃;

3) normalizing the hot-rolled coil and carrying out acid continuous rolling in sequence to obtain a cold-hard coil with the thickness of 0.500 +/-0.005 mm, wherein the normalizing temperature is 850-900 ℃;

4) the cold hard coil is processed in a continuous annealing furnace H₂+N₂Annealing the finished product at a constant speed in the mixed atmosphere, wherein the annealing temperature of the finished product is 820-880 ℃; and cooling, coating and finishing the annealed steel strip to obtain the non-oriented silicon steel.

Background

The non-oriented silicon steel is an iron core material of a rotor of a motor and a generator working in a rotating magnetic field, and the quality stability of the non-oriented silicon steel has important significance for improving the quality level of the motor. The Si content of the middle-low grade non-oriented silicon steel is controlled to be 0.5-1.7%, and the existing general production process route generally comprises steel making, casting blank, hot rolling, acid continuous rolling, annealing, coating and finishing. Wherein equiaxed ferrite and deformed ferrite are obtained in the hot rolling process, and the grain size of the ferrite and the proportion of the equiaxed ferrite are obviously influenced by the rolling temperature and the coiling temperature in the hot rolling process; and because the heat dissipation of the head and the tail of the hot-rolled coil is fast, the rolling temperature and the coiling temperature at the head and the tail of the hot-rolled coil are lower than those at the middle part of the hot-rolled coil, so that ferrite grains at the head and the tail are fine and the proportion of deformed ferrite is high compared with that at the middle part. Finally, the head and tail iron loss of the finished coils of the non-oriented silicon steel is high, the magnetic induction intensity is low, and the problem of inconsistent magnetic performance of coil passing is solved.

In order to solve the problem of inconsistent coil passing magnetic performance of medium-low grade non-oriented silicon steel, the conventional coping method mainly comprises annealing head and tail reduction production, namely, in the annealing process, the roller speed when the head and the tail of the steel coil are annealed is lower than the roller speed when the middle of the steel coil is annealed, so that the consistency of coil passing magnetic performance is improved through annealing.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide non-oriented silicon steel and a production method thereof, which solve the problem of inconsistent coil passing magnetic performance of the non-oriented silicon steel on the premise of not obviously increasing the production cost and meeting the requirements of middle and low-grade non-oriented silicon steel for small and medium-sized motors.

In order to achieve the above object, an embodiment of the present invention provides non-oriented silicon steel, which comprises the following chemical components by mass: less than or equal to 0.004 percent of C, less than or equal to 0.004 percent of S, 0.8 to 1.1 percent of Si, 0.2 to 0.4 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.004 percent of Nb, less than or equal to 0.006 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.03 percent of Cu, less than or equal to 0.004 percent of N, 0.15 to 0.30 percent of Al or less than or equal to 0.02 percent of Al, and the balance of Fe and inevitable impurities; the thickness of the non-oriented silicon steel is 0.500 +/-0.005 mm, and the non-oriented silicon steel is prepared by sequentially carrying out steelmaking, casting blank, hot rolling, normalizing, acid continuous rolling, finished product annealing, cooling, coating and finishing;

sn and Sb are not added during the steelmaking process;

in the hot rolling step: heating a casting blank obtained in the casting blank process to 1060-1120 ℃, preserving heat for more than 150min, rolling the casting blank into an intermediate blank with the thickness of 40-45 mm, and then passing the intermediate blank throughFinish rolling and coiling to obtain a hot rolled coil with the thickness of 3.00 +/-0.25 mm, wherein the start rolling temperature of the finish rolling is less than or equal to A_r1＝872℃ +1000*(11*[Si]-14*[Mn]+21*[Al]) In the formula [ Si ]]、[Mn]、[Al]Respectively representing the mass percentages of Si, Mn and Al in the casting blank; the finish rolling temperature is not more than 820 ℃, and the coiling temperature is not more than 560 ℃;

in the normalizing process, the normalizing temperature is 850-900 ℃;

in the finished product annealing process, the production is carried out at a constant speed, and the annealing temperature is 820-880 ℃.

Preferably, the non-oriented silicon steel has an iron loss P_1.5/50Less than or equal to 4.2W/kg and iron loss P of head, middle and tail_1.5/50Fluctuation less than or equal to 0.2W/kg and magnetic induction intensity B₅₀₀₀Magnetic induction B of not less than 1.72T and head, middle and tail₅₀₀₀The fluctuation is less than or equal to 0.02T.

Preferably, in the normalizing step, in pure dry N₂Normalizing the mixture for 120 to 150 seconds under the atmosphere.

Preferably, in the normalizing process, the normalizing temperature fluctuates by +/-10 ℃ and the production is carried out at a constant speed.

Preferably, in the annealing process, the annealing time is 50 +/-5 s, the annealing temperature fluctuates by +/-10 ℃, and the annealing is carried out at a constant speed.

In order to achieve the above object, an embodiment of the present invention provides a method for producing non-oriented silicon steel, comprising the steps of,

1) carrying out steel making under the condition of not adding Sn and Sb, and preparing a casting blank, wherein the casting blank comprises the following chemical components in percentage by mass: less than or equal to 0.004 percent of C, less than or equal to 0.004 percent of S, 0.8 to 1.1 percent of Si, 0.2 to 0.4 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.004 percent of Nb, less than or equal to 0.006 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.03 percent of Cu, less than or equal to 0.004 percent of N, 0.15 to 0.30 percent of Al or less than or equal to 0.02 percent of Al, and the balance of Fe and inevitable impurities;

2) heating the casting blank to 1060-1120 ℃, preserving heat for more than 150min, rolling the casting blank into an intermediate blank with the thickness of 40-45 mm, and then performing finish rolling and coiling on the intermediate blank to obtain a hot-rolled coil plate with the thickness of 3.00 +/-0.25 mm, wherein the finish rolling initial rolling temperature is less than or equal to A_r1＝872℃+1000*(11*[Si]-14*[Mn]+21*[Al]) In the formula [ Si ]]、[Mn]、[Al]Respectively Si, Mn and Mn in the casting blank,Mass percent of Al; the finish rolling temperature is not more than 820 ℃, and the coiling temperature is not more than 560 ℃;

3) normalizing the hot-rolled coil and carrying out acid continuous rolling in sequence to obtain a cold-hard coil with the thickness of 0.500 +/-0.005 mm, wherein the normalizing temperature is 850-900 ℃;

4) the cold hard coil is processed in a continuous annealing furnace H₂+N₂Annealing the finished product at a constant speed in the mixed atmosphere, wherein the annealing temperature of the finished product is 820-880 ℃; and cooling, coating and finishing the annealed steel strip to obtain the non-oriented silicon steel.

Preferably, in step 3, in pure dry N₂Normalizing the mixture for 120 to 150 seconds under the atmosphere.

Preferably, in step 3, the normalizing temperature fluctuates by ± 10 ℃ and the production is performed at a constant speed.

Preferably, in step 4, the annealing time is 50 +/-5 s, the annealing temperature fluctuates by +/-10 ℃, and the annealing is carried out at a constant production speed.

Preferably, the obtained non-oriented silicon steel has an iron loss P_1.5/50Less than or equal to 4.2W/kg and iron loss P of head, middle and tail_1.5/50Fluctuation less than or equal to 0.2W/kg and magnetic induction intensity B₅₀₀₀Magnetic induction B of not less than 1.72T and head, middle and tail₅₀₀₀The fluctuation is less than or equal to 0.02T.

In order to achieve the above object, an embodiment of the present invention provides a method for producing non-oriented silicon steel, comprising the steps of,

1) carrying out steel making according to the mass percent of Si and Mn in the chemical components of 0.8-1.1% and 0.2-0.4%, wherein Sn and Sb are not added during the steel making, and preparing a casting blank;

2) heating the casting blank to 1060-1120 ℃, preserving heat for more than 150min, rolling the casting blank into an intermediate blank with the thickness of 40-45 mm, and then performing finish rolling and coiling on the intermediate blank to obtain a hot-rolled coil plate with the thickness of 3.00 +/-0.25 mm, wherein the finish rolling initial rolling temperature is less than or equal to A_r1＝872℃+1000*(11*[Si]-14*[Mn]+21*[Al]) In the formula [ Si ]]、[Mn]、[Al]Respectively representing the mass percentages of Si, Mn and Al in the casting blank; the finish rolling temperature is not more than 820 ℃, and the coiling temperature is not more than 560 ℃;

3) normalizing the hot-rolled coil and carrying out acid continuous rolling in sequence to obtain a cold-hard coil with the thickness of 0.500 +/-0.005 mm, wherein the normalizing temperature is 850-900 ℃;

4) the cold hard coil is processed in a continuous annealing furnace H₂+N₂Annealing the finished product at a constant speed in the mixed atmosphere, wherein the annealing temperature of the finished product is 820-880 ℃; and cooling, coating and finishing the annealed steel strip to obtain the non-oriented silicon steel.

Compared with the prior art, the invention has the beneficial effects that:

(1) the non-oriented silicon steel finished product with the thickness of 0.500 +/-0.005 mm prepared by the production method has the iron loss of P_1.5/50Not more than 4.2W/kg, and magnetic induction intensity B₅₀₀₀The magnetic property is excellent, the magnetic property is basically the same as that of the existing non-oriented silicon steel with the Si content of 1.4-1.7%, the requirements of middle and low grade non-oriented silicon steel for medium and small motors can be met, the magnetic property of the coil passing through is consistent, and the iron loss P of the head, the middle and the tail is consistent_1.5/50Fluctuation less than or equal to 0.2W/kg and magnetic induction intensity B₅₀₀₀The fluctuation is less than or equal to 0.02T;

(2) the method comprises the steps of obtaining a hot-rolled coil plate with a completely deformed ferrite structure by adopting low-temperature rolling and low-temperature coiling processes in a hot rolling process, and combining an added normalizing process to ensure that the finally obtained non-oriented silicon steel has better magnetic performance, and meanwhile, under the condition of constant-speed production in a finished product annealing process, solving the problem of inconsistent head, middle and tail magnetic performances of a non-oriented silicon steel finished product in the prior art, and avoiding the condition that surface grains of a steel coil are abnormally grown compared with the inside grains during normalizing treatment;

(3) although the normalizing process is added, the production cost is not increased, the lower production cost is ensured, and the method has extremely high economic value. Specifically, the combination of the hot rolling process and the normalizing process fully exerts the effect of the normalizing process on the improvement of the structure of the non-oriented silicon steel hot rolled steel plate and the magnetic performance of the finished product, reduces the production cost of each process of steel making, hot rolling, acid continuous rolling, normalizing and annealing, and ensures that the cost of the whole process is not increased. In the steelmaking process, in terms of chemical components, the content of Si element for improving the magnetic property is reduced to 0.8-1.1% from the existing 1.4-1.7%, precious metals Sn and Sb for improving the magnetic property are not added, and the addition of Mn element is reduced, so that the steelmaking alloy cost is reduced on the premise of obtaining the magnetic property same as the existing chemical components. The hot rolling process adopts low-temperature rolling and low-temperature coiling processes, so that on one hand, the requirement on the temperature of a heating furnace is reduced, and on the other hand, the low-temperature heating is adopted, so that the energy consumption and the production cost are reduced compared with the existing hot rolling process; on the other hand, the surface iron scale of the hot-rolled coil is reduced, the burning loss is reduced, the yield is improved, and the production cost is reduced. Meanwhile, the thickness of the hot-rolled coil is increased from 2.0-2.5 mm to 3.00 +/-0.25 mm, the production rate of the hot-rolling process is increased, and the production cost of the hot-rolling process is integrally reduced. The normalizing process adopts the processes of low-temperature rolling and low-temperature coiling, so that the internal distortion of the hot-rolled coil is increased compared with the conventional high-temperature rolling and high-temperature coiling, the normalizing difficulty is reduced, and the low-temperature high-speed production in the normalizing process can be realized; in addition, the thickness of the hot-rolled coil is increased from 2.0-2.5 mm to 3.00 +/-0.25 mm, the production rate of the normalizing process is increased, and the production cost of the normalizing process is reduced on the whole. In the acid continuous rolling process, because the hot rolling adopts the processes of low-temperature rolling and low-temperature coiling, compared with the prior art, the iron oxide scales on the surface of the steel plate can be removed completely in the acid continuous rolling process more easily, the acid pickling difficulty in the acid continuous rolling process is correspondingly reduced, and the surface quality and the production rate of the product are improved; meanwhile, the thickness of the hot-rolled coil is increased from 2.0-2.5 mm to 3.00 +/-0.25 mm, the production rate of the acid continuous rolling process is increased, and the production cost of the acid continuous rolling process is integrally reduced. And in the annealing process, the hot rolling process and the normalizing process are combined, so that the head, middle and tail tissues of the obtained steel coil are uniform, the annealing process can adopt constant-speed low-temperature production, the production difficulty is reduced, the production efficiency is improved, and the production cost is reduced.

Drawings

FIG. 1 is a metallographic structure photograph of a hot-rolled steel sheet in comparative example 1, which was obtained by microscopic metallographic structure examination;

FIG. 2 is a metallographic structure photograph of the hot-rolled strip in comparative example 2 obtained by microscopic metallographic structure examination;

FIG. 3 is a metallographic structure photograph of the hot-rolled strip in comparative example 3 obtained by microscopic metallographic structure examination;

FIG. 4 is a metallographic structure photograph of the hot rolled strip in example 1 obtained by microscopic metallographic structure examination;

FIG. 5 is a metallographic structure photograph of the hot rolled strip in example 2 obtained by microscopic metallographic structure examination;

FIG. 6 is a metallographic structure photograph of the hot-rolled coil after the normalizing process in comparative example 2, which was obtained by microscopic metallographic structure examination.

Detailed Description

The invention provides non-oriented silicon steel and a production method thereof. The chemical components of the non-oriented silicon steel comprise 0.8-1.1 mass percent of Si and 0.2-0.4 mass percent of Mn, and the non-oriented silicon steel is prepared by sequentially carrying out steelmaking, casting blank, hot rolling, normalizing, acid continuous rolling, finished product annealing, cooling, coating and finishing. That is, the production method comprises the processes of steel making, casting, hot rolling, normalizing, acid continuous rolling, finished product annealing, cooling, coating, finishing and the like which are sequentially carried out. The production method is described in detail below in terms of the following steps.

Step 1) carrying out steel making according to the mass percent of Si and Mn in the chemical components of 0.8-1.1% and 0.2-0.4%, wherein Sn and Sb are not added during the steel making, and preparing a casting blank.

The step 1 includes a steel making process and a casting blank process.

The steel-making process may include processes of molten iron desulphurization, converter smelting, RH refining, etc. which are performed in sequence, and may be specifically implemented by using the existing feasible process means, which are not described in detail. The steel is made according to the mass percent of Si of 0.8-1.1% and the mass percent of Mn of 0.2-0.4%, and Sn and Sb are not added during the steel making, and correspondingly, the mass percent of Si of 0.8-1.1%, the mass percent of Mn of 0.2-0.4% and Sn and Sb are not contained in the chemical components of the obtained casting blank and the finally obtained non-oriented silicon steel finished product.

In one embodiment, the chemical components of the obtained casting blank and the finally obtained non-oriented silicon steel finished product comprise the following components in percentage by mass: less than or equal to 0.004 percent of C, less than or equal to 0.004 percent of S, 0.8 to 1.1 percent of Si, 0.2 to 0.4 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.004 percent of Nb, less than or equal to 0.006 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.03 percent of Cu, less than or equal to 0.004 percent of N, 0.15 to 0.30 percent of Al, and the balance of Fe and inevitable impurities. Or, in another embodiment, the chemical components of the obtained casting blank and the final non-oriented silicon steel product comprise, by mass: less than or equal to 0.004 percent of C, less than or equal to 0.004 percent of S, 0.8 to 1.1 percent of Si, 0.2 to 0.4 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.004 percent of Nb, less than or equal to 0.006 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.03 percent of Cu, less than or equal to 0.004 percent of N, less than or equal to 0.02 percent of Al, and the balance of Fe and inevitable impurities.

Preferably, the thickness of the casting blank obtained in the step 1 is more than or equal to 200mm, and the length of the casting blank is 10-11 m.

And 2) heating the casting blank obtained in the step 1 to 1060-1120 ℃, preserving heat for more than 150min, rolling the casting blank into an intermediate blank with the thickness of 40-45 mm, and then performing finish rolling and coiling on the intermediate blank to obtain a hot-rolled coil with the thickness of 3.00 +/-0.25 mm.

This step 2 is also referred to as a hot rolling process. Wherein: the initial rolling temperature of finish rolling is less than or equal to A_r1＝872℃ +1000*(11*[Si]-14*[Mn]+21*[Al]) In the formula [ Si ]]、[Mn]、[Al]Respectively the mass percentages of Si, Mn and Al in the casting blank obtained in the step 1. That is, the mass percentages of Si, Mn, and Al in the cast slab obtained in step 1 [ Si%]、[Mn]、[Al]Calculating to obtain A_r1＝872℃+1000*(11*[Si]-14*[Mn]+21*[Al]) In the step 2, the finish rolling start temperature is controlled to be A or less_r1. And the finish rolling temperature of the finish rolling is controlled to be less than or equal to 820 ℃, and the coiling temperature is controlled to be less than or equal to 560 ℃.

In this way, in the present embodiment, the hot rolling process adopts the low-temperature rolling and low-temperature coiling processes, so that each pass in the finish rolling is ensured to be performed in the ferrite region, and the final pass of the finish rolling is performed in the low-temperature ferrite region, so that no gamma/alpha phase transformation exists in the finish rolling process, the structure of the obtained hot-rolled coil is a single-phase structure of the completely deformed ferrite, and based on the structure, the uniformity of the structure of the hot-rolled coil can be ensured under the condition that the heat dissipation speeds of the head, the middle and the tail of the hot-rolled coil are different, and further, the foundation is laid for obtaining the non-oriented silicon steel finished product with consistent magnetic performance of the coil in the follow-up process.

In addition, in the embodiment, the hot rolling process adopts low-temperature rolling and low-temperature coiling processes, so that the requirement on the temperature of the heating furnace is reduced, the solid solution of precipitates in the casting blank is reduced by adopting low-temperature heating, the growth of structure grains is facilitated, the excellent magnetic performance of the subsequent non-oriented silicon steel finished product is ensured, and the production cost is reduced compared with the existing hot rolling process.

And 3) normalizing and acid continuous rolling the hot-rolled coil obtained in the step 2 in sequence to obtain a cold-hard coil with the thickness of 0.500 +/-0.005 mm, wherein the normalizing temperature is 850-900 ℃.

In step 3, the normalizing step and the acid continuous rolling step are also performed.

The normalizing process is usually applied to the production of high-grade non-oriented silicon steel, that is, the production process route of the high-grade non-oriented silicon steel adopts steel making, casting blank, hot rolling, normalizing, acid continuous rolling, annealing, coating and finishing, however, for the existing production method of medium and low-grade non-oriented silicon steel, the normalizing process is added as the high-grade non-oriented silicon steel, and although the condition that the head and tail magnetic properties are inconsistent can be improved to a certain extent, the surface crystal grains of a hot-rolled coil plate grow abnormally compared with the inside, so that the surface serious chromatic aberration of the steel coil after the acid continuous rolling is judged, and the production cost is increased. In the production method, the hot-rolled coil plate with a completely deformed ferrite structure is obtained by adopting the low-temperature rolling and low-temperature coiling processes in the hot-rolling process in the step 2, so that a foundation is laid for the normalizing process, the problem that surface grains of the steel coil are abnormally long compared with the inside grains in the steel coil in the conventional normalizing process is solved, namely, the grains at each part of the steel coil after the normalizing process are uniformly grown, and the normalizing process can also ensure that the finally obtained non-oriented silicon steel has better magnetic performance; moreover, the completely deformed ferrite structure of the hot-rolled coil accumulates extremely high storage energy, so that the normalizing difficulty can be reduced, low-temperature high-speed production in a normalizing process is realized, and excessive increase of production cost due to increase of the normalizing process is avoided; in addition, due to the smooth implementation of the normalizing process, the magnetic performance of the finally obtained non-oriented silicon steel can be greatly improved, in this case, in the aspect of chemical components, the content of Si element for improving the magnetic performance is reduced to 0.8-1.1% from the existing 1.4-1.7%, precious metals Sn and Sb for improving the magnetic performance are not added, and the addition of Mn element is reduced, so that the magnetic performance same as that of the existing chemical components can be obtained, and the alloy cost can be reduced.

Further preferably, in the normalizing step, the N is pure dry₂Normalizing the mixture for 120 to 150 seconds under the atmosphere. In addition, in the normalizing process, the normalizing temperature fluctuates by +/-10 ℃, namely, the normalizing temperature is controlled within a fluctuation range of +/-10 ℃, so that the maximum value and the minimum value of the temperature during normalizing do not exceed 20 degrees of difference; in the normalizing process, constant-speed production is carried out, namely the roller speed is constant when the head, the middle and the tail of the steel coil are normalized.

In addition, in the embodiment, by adopting the processes of low-temperature heating, low-temperature rolling and low-temperature coiling in the hot rolling process in the step 2, the oxide scales on the surface of the hot-rolled coil are reduced, and the burning loss is reduced, so that the oxide scales on the surface of the steel plate are easier to remove in the acid continuous rolling process in the step 3, the acid pickling difficulty in the acid continuous rolling process is correspondingly reduced, and the surface quality and the production rate of the product are improved; in addition, as mentioned above, the low-temperature heating is adopted in the hot rolling process of the step 2, so that the growth of the structure crystal grains is facilitated, and the increase of the normalizing process is combined, so that the thickness of the hot-rolled coil plate of the step 2 can be increased from the existing 2.0-2.5 mm to 3.00 +/-0.25 mm, and the larger the thickness of the hot-rolled coil plate is, the larger the amount of steel subjected to acid pickling treatment in the acid continuous rolling process of the step 3 at the same roll speed is, the production rate of the acid continuous rolling process is further improved, and the production cost of the acid continuous rolling process is reduced on the whole.

In addition, as mentioned above, due to the combination of low-temperature heating and normalizing in the hot rolling process, the thickness of the hot-rolled coil can be increased from 2.0-2.5 mm to 3.00 +/-0.25 mm, and the increase of the thickness of the hot-rolled coil can greatly reduce the difficulty of the hot rolling process in the hot rolling process and improve the production efficiency of the hot rolling process.

Further preferably, in the acid continuous rolling process in step 3, HCl is firstly used for carrying out three-stage acid washing, and then rinsing, drying and cold rolling are carried out to obtain a cold-hard coil.

Step 4) adopting a continuous annealing furnace to cool and harden the coil obtained in the step 3H₂+N₂Annealing the finished product at a constant speed in the mixed atmosphere, wherein the annealing temperature of the finished product is 820-880 ℃; and cooling, coating and finishing the annealed steel strip to obtain a finished product of the non-oriented silicon steel.

This step 4, namely the finished product annealing process, cooling process, coating and finishing process.

In the embodiment, as can be seen from the foregoing, based on the step 2 hot rolling process and the step 3 normalizing process, the head, middle and tail structures of the obtained steel coil are uniform, and further the product annealing process in the step 4 adopts low-temperature constant-speed production, and then through conventional cooling, coating and finishing, the non-oriented silicon steel with a thickness of 0.500 ± 0.005mm and excellent magnetic properties of the head, middle and tail is obtained, and it is not necessary to adopt annealing head and tail speed reduction production as in the prior art, so that the production difficulty is reduced, and the production efficiency is improved.

The constant-speed production of the finished product annealing process, namely the constant-speed production in the finished product annealing process, namely the constant-speed production of the roll when the head, the middle and the tail of the steel coil are annealed, is constant.

Further preferably, in the annealing process of the finished product in the step 4, the annealing time is 50 +/-5 s, and the annealing temperature of the finished product fluctuates by +/-10 ℃, namely, the maximum value and the minimum value of the temperature during the annealing of the finished product do not exceed 20 degrees of difference.

Further preferably, in the cooling process in the step 4, the steel strip after the finished product annealing is cooled by adopting three-section cooling, so that the residual stress of the steel strip is effectively controlled to be less than or equal to 50MPa, and the control of the shape of the steel strip is facilitated.

The non-oriented silicon steel of one embodiment of the invention is prepared by the production method, the thickness of the non-oriented silicon steel is 0.500 +/-0.005 mm, and the non-oriented silicon steel comprises the following chemical components in percentage by mass: less than or equal to 0.004 percent of C, less than or equal to 0.004 percent of S, 0.8 to 1.1 percent of Si, 0.2 to 0.4 percent of Mn, less than or equal to 0.03 percent of P, less than or equal to 0.004 percent of Nb, less than or equal to 0.006 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.03 percent of Cr, less than or equal to 0.03 percent of Ni, less than or equal to 0.03 percent of Cu, less than or equal to 0.004 percent of N, 0.15 to 0.30 percent of Al or less than or equal to 0.02 percent of Al, and the balance of Fe and inevitable impurities.

The non-oriented silicon steel has iron loss P_1.5/50Not more than 4.2W/kg, magnetic induction intensityB₅₀₀₀The magnetic property is excellent, the magnetic property is basically the same as that of the existing non-oriented silicon steel with the Si content of 1.4-1.7%, the requirements of middle and low grade non-oriented silicon steel for medium and small motors can be met, the magnetic property of the coil passing through is consistent, and the iron loss P of the head, the middle and the tail is consistent_1.5/50Fluctuation less than or equal to 0.2W/kg and magnetic induction intensity B₅₀₀₀Fluctuation is less than or equal to 0.02T, namely, the iron loss P of the head, the middle and the tail of the finished steel coil of non-oriented silicon steel_1.5/50The difference between the maximum value and the minimum value of (B) is less than or equal to 0.2W/kg, and the head, the middle and the tail of B₅₀₀₀The difference between the maximum value and the minimum value of (A) is less than or equal to 0.02T.

Compared with the prior art, the invention has the beneficial effects that:

(1) the finished non-oriented silicon steel product prepared by the production method has excellent magnetic performance, can meet the requirements of middle and low-grade non-oriented silicon steel for medium and small motors, has consistent coil passing magnetic performance and head, middle and tail iron loss P_1.5/50And magnetic induction B₅₀₀₀The fluctuation is small, and the magnetic property stability of the non-oriented silicon steel finished product is improved;

(2) the method comprises the steps of obtaining a hot-rolled coil plate with a completely deformed ferrite structure by adopting low-temperature rolling and low-temperature coiling processes in a hot rolling process, and combining an added normalizing process to ensure that the finally obtained non-oriented silicon steel has better magnetic performance, and meanwhile, under the condition of constant-speed production in a finished product annealing process, solving the problem of inconsistent head, middle and tail magnetic performances of a non-oriented silicon steel finished product in the prior art, and avoiding the condition that surface grains of a steel coil are abnormally grown compared with the inside grains during normalizing treatment;

(3) although the normalizing process is added, the production cost is not increased, the lower production cost is ensured, and the method has extremely high economic value. Specifically, the combination of the hot rolling process and the normalizing process fully exerts the effect of the normalizing process on the improvement of the structure of the non-oriented silicon steel hot rolled steel plate and the magnetic performance of the finished product, reduces the production cost of each process of steel making, hot rolling, acid continuous rolling, normalizing and annealing, and ensures that the cost of the whole process is not increased. In the steelmaking process, in terms of chemical components, the content of Si element for improving the magnetic property is reduced to 0.8-1.1% from the existing 1.4-1.7%, precious metals Sn and Sb for improving the magnetic property are not added, and the addition of Mn element is reduced, so that the steelmaking alloy cost is reduced on the premise of obtaining the magnetic property same as the existing chemical components. The hot rolling process adopts low-temperature rolling and low-temperature coiling processes, so that on one hand, the requirement on the temperature of a heating furnace is reduced, and on the other hand, the low-temperature heating is adopted, so that the energy consumption and the production cost are reduced compared with the existing hot rolling process; on the other hand, the surface iron scale of the hot-rolled coil is reduced, the burning loss is reduced, the yield is improved, and the production cost is reduced. Meanwhile, the thickness of the hot-rolled coil is increased from 2.0-2.5 mm to 3.00 +/-0.25 mm, the production rate of the hot-rolling process is increased, and the production cost of the hot-rolling process is integrally reduced. The normalizing process adopts the processes of low-temperature rolling and low-temperature coiling, so that the internal distortion of the hot-rolled coil is increased compared with the conventional high-temperature rolling and high-temperature coiling, the normalizing difficulty is reduced, and the low-temperature high-speed production in the normalizing process can be realized; in addition, the thickness of the hot-rolled coil is increased from 2.0-2.5 mm to 3.00 +/-0.25 mm, the production rate of the normalizing process is increased, and the production cost of the normalizing process is reduced on the whole. In the acid continuous rolling process, because the hot rolling adopts the processes of low-temperature rolling and low-temperature coiling, compared with the prior art, the iron oxide scales on the surface of the steel plate can be removed completely in the acid continuous rolling process more easily, the acid pickling difficulty in the acid continuous rolling process is correspondingly reduced, and the surface quality and the production rate of the product are improved; meanwhile, the thickness of the hot-rolled coil is increased from 2.0-2.5 mm to 3.00 +/-0.25 mm, the production rate of the acid continuous rolling process is increased, and the production cost of the acid continuous rolling process is integrally reduced. And in the annealing process, the hot rolling process and the normalizing process are combined, so that the head, middle and tail tissues of the obtained steel coil are uniform, the annealing process can adopt constant-speed low-temperature production, the production difficulty is reduced, the production efficiency is improved, and the production cost is reduced.

The detailed description set forth above is merely a specific description of possible embodiments of the present invention and is not intended to limit the scope of the invention, which is intended to include within the scope of the invention equivalent embodiments or modifications that do not depart from the technical spirit of the present invention.

The advantages of the invention are further illustrated below by 3 comparative examples and 2 examples, of course, these 2 examples are only some, but not all, of the many variations that the invention comprises. 3 comparative examples and 2 examples respectively provide non-oriented silicon steel, and the production method thereof is as follows.

Step 1)

And (3) steelmaking, and then preparing a casting blank, wherein the chemical components of the casting blank are shown in the table 1 in percentage by mass, the thickness of the casting blank is also shown in the table 1, and the length of the casting blank is 10-11 m.

[ Table 1]

Step 2)

And (3) heating the casting blank obtained in the step (1), then rolling the casting blank into an intermediate blank, and then performing finish rolling and coiling on the intermediate blank to obtain a hot-rolled coil. Wherein, in the example 1 and the example 2, the mass percentages of Si, Mn and Al in the casting blank obtained in the step 1 [ Si]、[Mn]、[Al]Calculating to obtain A_r1＝872℃

+1000*(11*[Si]-14*[Mn]+21*[Al]) In the step 2, the finish rolling start temperature is controlled to be A or less_r1. And the finish rolling temperature of the finish rolling is controlled to be less than or equal to 820 ℃, and the coiling temperature is controlled to be less than or equal to 560 ℃ so as to obtain a complete deformation structure. And in the comparative examples 1 to 3, conventional high-temperature finish rolling and high-temperature coiling processes are adopted to obtain recrystallized structures as much as possible.

The heating temperature, the holding time, the intermediate billet thickness, the finish rolling start temperature, the finish rolling finish temperature, the coiling temperature, and the hot rolled coil thickness of comparative examples 1 to 3 and examples 1 to 2 are shown in table 2.

[ Table 2]

The hot rolled coils obtained in comparative examples 1 to 3 and examples 1 to 2 were subjected to metallographic structure examination, and the results of examination are shown in fig. 1 to 5, from which: the structures of comparative examples 1 to 3 are composite structures of deformed ferrite and equiaxed ferrite; the structures of examples 1 to 2 were all completely deformed ferrite structures, and did not contain equiaxed ferrite structures.

Step 3)

Directly carrying out acid continuous rolling on the hot rolled coils obtained in the comparative example 1 and the comparative example 3 obtained in the step 2 to obtain a cold-hard coil with the thickness of 0.500 +/-0.005 mm; normalizing the hot rolled coils obtained in the step 2 and the hot rolled coils obtained in the examples 1-2 in sequence to obtain cold-hard coils with the thickness of 0.500 +/-0.005 mm, wherein the normalization is carried out in pure dry N₂The method is carried out in an atmosphere, and the normalizing temperature is 850-900 ℃.

Specifically, key parameters such as normalizing temperature, normalizing time, normalizing temperature fluctuation, pickling speed, cold-hard roll thickness, and raw material thickness of each comparative example and example are shown in table 3.

[ Table 3]

Here, the hot-rolled coils obtained after the normalization step in comparative example 2 and examples 1 to 2 were subjected to microscopic metallographic structure examination, and found that: referring to the test result of comparative example 2 shown in fig. 6, abnormal grain growth occurred on the surface of the hot-rolled coil after the normalizing process of comparative example 2; the hot rolled coil obtained after the normalizing process in examples 1 to 2 had a completely equiaxed ferrite structure and a uniform structure.

In comparative examples 1 to 3 and examples 1 to 2, the surface quality of each of the cold-hardened coils obtained after pickling was good. As can be seen, the thickness of the hot rolled coil before the acid continuous rolling in examples 1 to 2 was 3.00mm, which was 2.50mm higher than that in comparative examples 1 to 3, and the practical production efficiency in examples 1 to 2 was high.

Step 4)

The cold hard coil obtained in the step 3 is processed in a continuous annealing furnace in H₂+N₂Annealing the finished product in the mixed atmosphere. During the annealing of finished products, the comparative example 2 and the examples 1-2 are produced at constant speed in the whole process, and the comparative examples 1 and 3 adopt head-tail speed reduction production to eliminate head-to-tail difference as much as possible; wherein the annealing temperature fluctuates by + -10 deg.C, i.e., during annealing of the final productThe temperature maximum and minimum values do not exceed a 20 ° difference.

And cooling, coating and finishing the annealed steel strip to obtain a finished product of the non-oriented silicon steel. In the cooling procedure, the steel strip after the finished product annealing is cooled by adopting three-section type cooling, so that the residual stress of the steel strip is effectively controlled to be less than or equal to 50MPa, and the control of the strip shape is facilitated.

The annealing temperature, annealing time, annealing speed, head and tail annealing time and head and tail annealing speed of the finished product are respectively shown in table 4.

[ Table 4]

	Annealing temperature (. degree.C.)	Annealing time (S)	Annealing speed (m/min)	Annealing time of head and tail (S)	Head and tail annealing speed (m/min)
						Comparative example 1	900	55	150	61	135
Comparative example 2	900	55	150	55	150
						Comparative example 3	950	55	150	61	135
Example 1	850	55	150	55	150
						Example 2	850	55	150	55	150

The finished non-oriented silicon steel products obtained in comparative examples 1-3 and examples 1-2 were tested, and the magnetic properties and surface determination results are shown in table 5.

[ Table 5]

As can be seen from table 5: comparative examples 1 and 3, the normalization process is not performed, and even if the head and the tail of the annealing process are subjected to speed reduction production, the difference between the magnetic properties of the head and the tail and the magnetic properties of the middle part cannot be completely eliminated; compared with the comparative example 2 and the examples 1-2, through the normalizing process, the whole annealing process is produced at a constant speed, and the difference between the magnetic properties of the head, the tail and the middle is small; but the abnormal growth of crystal grains appears on the surface in the normalizing process of the comparative example 2, so that the surface quality of the finished product is judged.

In the view of the whole production process, in the embodiments 1-2, compared with the comparative example 3, the contents of Si and Mn are both greatly reduced, Sn is not added in the steelmaking process (Sn contained in the finished product is inevitably introduced in molten iron or other alloys), that is, the cost of the steelmaking alloy is reduced, the thickness of the hot-rolled coil is increased, the hot-rolling, normalizing and acid continuous rolling speeds are increased, the production cost is reduced, the constant-speed production in the annealing process improves the annealing production efficiency and reduces the cost, so that the obtained non-oriented silicon steel finished product has low iron loss, small fluctuation of iron loss at the head, the middle and the tail, and the magnetic induction intensity B under the condition of low overall alloy cost and production cost₅₀₀₀Greatly increased and head, middle and tail magnetic induction intensity B₅₀₀₀The fluctuation is small.

In summary, as can be seen from the above examples 1-2, the non-oriented silicon steel produced by the embodiment of the invention has high production efficiency and low cost; in addition, the magnetic performance of the obtained non-oriented silicon steel finished product is higher than that of the existing non-oriented silicon steel with the same Si content (for example, the Si content of the non-oriented silicon steel of examples 1-2 is 0.94% and 1.05%, the magnetic performance of the non-oriented silicon steel is not Sn, and is higher than that of the non-oriented silicon steel of comparative example 3 in the prior art, the Si content of the non-oriented silicon steel is 1.54% + 0.025% Sn), the annealing process is carried out at a constant speed, and the consistency of the head magnetic performance and the tail magnetic performance is high.