1. 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 in the chemical components of 0.3-1.2%, and preparing a casting blank;

2) heating the casting blank to 1050-1150 ℃, 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 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 representing the mass percentages of Si, Mn and Al in the casting blank obtained in the step 1; when A is_r1More than or equal to 1000 ℃, the finish rolling temperature T is less than or equal to 840 ℃, otherwise, T is less than or equal to A_r1-160 ℃; the coiling temperature is less than or equal to 550 ℃;

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 850-950 ℃;

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 820-950 ℃; and cooling, coating and finishing the annealed steel strip to obtain a finished product of the non-oriented silicon steel.

2. The method for producing non-oriented silicon steel according to claim 1, wherein the thickness of the obtained cast slab in step 1 is 200 to 240 mm.

3. Method for producing non-oriented silicon steel according to claim 1 characterised in that in step 3, pure dry N is used₂Normalizing the mixture for 120 to 150 seconds under the atmosphere.

4. The method for producing a non-oriented silicon steel according to claim 1, wherein in step 3, the normalizing temperature fluctuates by ± 10 ℃, and the normalizing is produced at a constant rate.

5. The method for producing non-oriented silicon steel according to claim 1, wherein the acid continuous rolling in step 3 is performed by performing three-stage pickling with HCl, and then rinsing, drying and cold rolling to obtain a chilled coil with a thickness of 0.500 ± 0.005 mm.

6. Method for producing non-oriented silicon steel according to claim 1 characterised in that the annealing time in step 4 is 50 ± 5 s.

7. The method for producing a non-oriented silicon steel according to claim 1, wherein the final annealing temperature of step 4 fluctuates by ± 10 ℃, and the annealing is performed at a constant rate.

8. The method for producing a non-oriented silicon steel according to claim 1, wherein the finished annealed steel strip is subjected to three-stage cooling in step 4 to control the residual stress of the steel strip to be not more than 50 MPa.

9. The method for producing non-oriented silicon steel according to any one of claims 1 to 8, wherein in step 1, steel is made with 0.3% to 0.6% Si in chemical composition, and the finished non-oriented silicon steel obtained in the production method has an iron loss P of_1.5/50Less than or equal to 5.0W/kg and fluctuation in head, middle and tail<0.25W/kg; alternatively, the first and second electrodes may be,

in the step 1, according to 0.6 percent of chemical components<The Si content is less than or equal to 0.9 percent, and the iron loss P of the finished product of the non-oriented silicon steel obtained in the production method is_1.5/50Not more than 4.5W/kg and fluctuation in head, middle and tail<0.20W/kg; alternatively, the first and second electrodes may be,

in the step 1, according to 0.9 percent of chemical components<The Si content is less than or equal to 1.2 percent, and the iron loss P of the finished product of the non-oriented silicon steel obtained in the production method is_1.5/50Not more than 4.0W/kg and fluctuation in head, middle and tail<0.15W/kg。

10. The method of producing non-oriented silicon steel according to any one of claims 1 to 8, wherein in step 1, steel is made with 0.3% to 0.6% Si in chemical composition, and the non-oriented silicon steel obtained in the production methodMagnetic induction B of the finished product₅₀₀₀Not less than 1.75T and fluctuates head, middle and tail<0.015T; alternatively, the first and second electrodes may be,

in the step 1, according to 0.6 percent of chemical components<The Si content is less than or equal to 0.9 percent, and the magnetic induction intensity B of the finished product of the non-oriented silicon steel obtained in the production method₅₀₀₀Not less than 1.73T and fluctuation in head, middle and tail<0.015T; alternatively, the first and second electrodes may be,

in the step 1, according to 0.9 percent of chemical components<The Si content is less than or equal to 1.2 percent, and the magnetic induction intensity B of the finished non-oriented silicon steel product obtained in the production method₅₀₀₀Not less than 1.71T and fluctuating head, middle and tail<0.015T。

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 a production method of non-oriented silicon steel, which solves the problem of inconsistent coil passing magnetic performance of medium and low grade non-oriented silicon steel and ensures good magnetic performance on the premise of not obviously increasing the production cost.

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 in the chemical components of 0.3-1.2%, and preparing a casting blank;

2) heating the casting blank to 1050-1150 ℃, 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 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 representing the mass percentages of Si, Mn and Al in the casting blank obtained in the step 1; when A is_r1More than or equal to 1000 ℃, the finish rolling temperature T is less than or equal to 840 ℃, otherwise, T is less than or equal to A_r1-160 ℃; the coiling temperature is less than or equal to 550 ℃;

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 850-950 ℃;

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 820-950 ℃; and cooling, coating and finishing the annealed steel strip to obtain a finished product of the non-oriented silicon steel.

Preferably, in the step 1, the thickness of the obtained casting blank is 200-240 mm.

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 normalizing is produced at a constant speed.

Preferably, in the step 3, when acid continuous rolling is performed, HCl is adopted for three-stage acid washing, and then rinsing, drying and cold rolling are performed to obtain a cold hard coil with the thickness of 0.500 +/-0.005 mm.

Preferably, the annealing time in step 4 is 50 ± 5 s.

Preferably, the annealing temperature of the finished product in the step 4 fluctuates by +/-10 ℃, and the annealing is carried out at a constant production speed.

Preferably, the steel strip after the finished product annealing is subjected to three-section cooling in the step 4, so that the residual stress of the steel strip is controlled to be less than or equal to 50 MPa.

Preferably, in the step 1, steel making is carried out according to the chemical composition of more than or equal to 0.3 percent and less than or equal to 0.6 percent of Si, and the iron loss P of the finished non-oriented silicon steel product obtained in the production method is_1.5/50Less than or equal to 5.0W/kg and fluctuation in head, middle and tail<0.25W/kg; alternatively, the first and second electrodes may be,

in the step 1, according to 0.6 percent of chemical components<The Si content is less than or equal to 0.9 percent, and the iron loss P of the finished product of the non-oriented silicon steel obtained in the production method is_1.5/50Not more than 4.5W/kg and fluctuation in head, middle and tail<0.20W/kg; alternatively, the first and second electrodes may be,

in the step 1, according to 0.9 percent of chemical components<The Si content is less than or equal to 1.2 percent, and the iron loss P of the finished product of the non-oriented silicon steel obtained in the production method is_1.5/50Not more than 4.0W/kg and fluctuation in head, middle and tail<0.15W/kg。

Preferably, in the step 1, steel making is carried out according to the chemical composition of more than or equal to 0.3 percent and less than or equal to 0.6 percent of Si, and the magnetic induction intensity B of the finished non-oriented silicon steel product obtained in the production method is₅₀₀₀Not less than 1.75T and fluctuates head, middle and tail<0.015T; alternatively, the first and second electrodes may be,

in the step 1, according to 0.6 percent of chemical components<The Si content is less than or equal to 0.9 percent, and the magnetic induction intensity B of the finished product of the non-oriented silicon steel obtained in the production method₅₀₀₀Not less than 1.73T and fluctuation in head, middle and tail<0.015T; alternatively, the first and second electrodes may be,

in step 1, according to0.9 percent of chemical components<The Si content is less than or equal to 1.2 percent, and the magnetic induction intensity B of the finished non-oriented silicon steel product obtained in the production method₅₀₀₀Not less than 1.71T and fluctuating head, middle and tail<0.015T。

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

(1) the finished non-oriented silicon steel product with the thickness of 0.500 +/-0.005 mm prepared by the production method can obtain the magnetic performance of the prior art with a higher Si content range in a lower Si content range, for example, the iron loss P of the finished non-oriented silicon steel product with the Si content of 0.3-0.6% in the invention_1.5/50Less than or equal to 5.0W/kg, and magnetic induction intensity B₅₀₀₀The silicon-based alloy is more than or equal to 1.75T, and is comparable to or even exceeds the non-oriented silicon steel with Si content of 0.8-1.1% in the prior art; 0.6 percent in the invention<The iron loss P of the non-oriented silicon steel finished product with the Si less than or equal to 0.9 percent_1.5/50Not more than 4.5W/kg, and magnetic induction intensity B₅₀₀₀1.73T or more, which is equal to or even more than the non-oriented silicon steel with Si content of 1.1-1.4% in the prior art; 0.9 percent in the invention<The iron loss P of the finished non-oriented silicon steel product with the Si content less than or equal to 1.2 percent_1.5/50Not more than 4.0W/kg, and magnetic induction intensity B₅₀₀₀1.71T or more, which is comparable to or even exceeds the non-oriented silicon steel with the Si content of 1.4-1.7% in the prior art; therefore, the finished product of the non-oriented silicon steel 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 iron loss P of the head, the middle and the tail_1.5/50Rate of fluctuation<0.15-0.25W/kg, magnetic induction B₅₀₀₀Wave motion<0.015T, which is also not available in the prior art;

(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 elements for improving the magnetic property is respectively reduced from 1.4-1.7%/1.1-1.4%/0.8-1.1% to 0.9-1.2%/0.6-0.9%/0.3-0.6%, noble metals Sn and Sb for improving the magnetic property are not added any more, and the addition of Mn elements is reduced, so that the steelmaking alloy cost is reduced on the premise of obtaining the magnetic property same as that of 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.

Detailed Description

In one embodiment of the present invention, a method for producing non-oriented silicon steel is provided. Specifically, the production method includes the following steps.

Step 1) carrying out steel making according to the mass percent of Si in the chemical components of 0.3-1.2%, and preparing a casting blank.

In the step 1, namely the steelmaking process and the casting blank process, steelmaking is performed according to the mass percent of Si in the chemical components of 0.3-1.2%, and correspondingly, the mass percent of Si in the chemical components of the obtained casting blank and the final non-oriented silicon steel finished product is 0.3-1.2%.

Preferably, the thickness of the casting blank obtained in the step 1 is 200-240 mm, and the length is 10-11 m.

And 2) heating the casting blank obtained in the step 1 to 1050-1150 ℃, 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 when A is_r1The finish rolling temperature T is not more than 840 ℃ when the temperature is not less than 1000 ℃, otherwise, the temperature is when A_r1Less than 1000 ℃, and the finishing temperature T of finish rolling is less than or equal to A_r1-160 ℃. In addition, the coiling temperature is less than or equal to 550 ℃.

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 850-950 ℃.

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 the normalizing process can be realized, and excessive increase of production cost due to increase of the normalizing process can be avoided.

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 continuous cold hard coils obtained in the step 3Annealing furnace in H₂+N₂Annealing the finished product at a constant speed in the mixed atmosphere, wherein the annealing temperature of the finished product is 820-950 ℃; 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.

Thus, when the content of Si in the non-oriented silicon steel product obtained in the embodiment is not less than 0.3% and not more than 0.6%, that is, when steel is further smelted in step 1 according to the content of Si in the chemical composition of not less than 0.3% and not more than 0.6%, the iron loss P of the non-oriented silicon steel product obtained in the embodiment is P_1.5/50Less than or equal to 5.0W/kg, and magnetic induction intensity B₅₀₀₀Not less than 1.75T; when the content is 0.6 percent<When the content of Si is less than or equal to 0.9 percent, namely when the steel making is further carried out according to the chemical composition that Si is more than 0.6 percent and less than or equal to 0.9 percent in the step 1, the iron loss P of the finished product of the non-oriented silicon steel obtained by the embodiment_1.5/50Not more than 4.5W/kg, and magnetic induction intensity B₅₀₀₀Not less than 1.73T; when the content is 0.9 percent<When the content of Si is less than or equal to 1.2 percent, namely when the steel making is further carried out according to the chemical composition that Si is more than 0.9 percent and less than or equal to 1.2 percent in the step 1, the iron loss P of the finished product of the non-oriented silicon steel obtained by the embodiment_1.5/50Not more than 4.0W/kg, and magnetic induction intensity B₅₀₀₀Not less than 1.71T; as can be seen, the finished product of the invention has excellent magnetic performance, can meet the requirements of medium and low-grade non-oriented silicon steel for medium and small motors, and can obtain the magnetic performance in a higher Si content range in the prior art in a lower Si content range, for example, the magnetic performance of the non-oriented silicon steel with Si content of more than 0.3% and less than or equal to 0.6% in the invention is comparable to or even more than that of the non-oriented silicon steel with Si content of 0.8-1.1% in the prior art, but 0.6%<The magnetic performance of the silicon steel with Si less than or equal to 0.9 percent is comparable to or even more than that of non-oriented silicon steel with Si content of 1.1 to 1.4 percent in the prior art and 0.9 percent<The magnetic performance of the silicon steel with the Si content less than or equal to 1.2 percent is comparable to or even superior to that of non-oriented silicon steel with the Si content of 1.4-1.7 percent in the prior art; the magnetic properties of the coil are consistent, and the iron loss P of the coil in the head, the middle and the tail is_1.5/50Rate of fluctuation<0.15-0.25W/kg, magnetic induction B₅₀₀₀Wave motion<0.015T, i.e. the head-to-tail iron loss P of the finished steel coil of non-oriented silicon steel_1.5/50Is a difference between the maximum value and the minimum value of<0.15-0.25W/kg, head-to-tail B₅₀₀₀Is a difference between the maximum value and the minimum value of<0.015T。

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 elements for improving the magnetic property is respectively reduced from 1.4-1.7%/1.1-1.4%/0.8-1.1% to 0.9-1.2%/0.6-0.9%/0.3-0.6%, noble metals Sn and Sb for improving the magnetic property are not added any more, and the addition of Mn elements is reduced, so that the steelmaking alloy cost is reduced on the premise of obtaining the magnetic property same as that of 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 this embodiment are further illustrated by the following 3 comparative examples and 3 examples, of course, these 3 examples are only a part, but not all, of the many variations of the present invention. 3 comparative examples and 3 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, and the thickness of the casting blank is also shown in the table 1.

[ 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 examples 1 to 3, the mass percentages of Si, Mn and Al in the cast slab 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. When A is_r1The finish rolling temperature T is not more than 840 ℃ when the temperature is not less than 1000 ℃, otherwise, the temperature is when A_r1Less than 1000 ℃, and the finishing temperature T of finish rolling is less than or equal to A_r1-160 ℃. In addition, the coiling temperature is less than or equal to 550 ℃.

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 3 are shown in table 2.

[ Table 2]

In this case, the hot rolled coils obtained in comparative examples 1 to 3 and examples 1 to 3 were subjected to metallographic microstructure examination, and found that: (1) the structure of each comparative example is a deformed ferrite and equiaxed ferrite composite structure; the head, the tail and the edge of the hot-rolled coil are fine in ferrite grains and high in deformation ferrite proportion; in the middle of the hot-rolled coil, ferrite recrystallization proportion is high and crystal grains are large; the through coil structure difference of the hot-rolled coil is large; (2) the structure of each embodiment is a completely deformed ferrite structure and does not contain an equiaxed ferrite structure; the head, the middle, the tail and the edge of the hot rolled plate coil are all completely deformed ferrite tissues; the hot-rolled coil is uniform in coil-through structure.

Step 3)

And (3) directly carrying out acid continuous rolling on the hot rolled coils obtained in the comparative examples 1-3 obtained in the step 2 to obtain the cold-hard coils with the thickness of 0.500 +/-0.005 mm.

And (3) normalizing the hot rolled coils obtained in the step (2) and obtained in the examples 1 to 3 in sequence, and carrying out acid continuous rolling to obtain the cold-hard coils with the thickness of 0.500 +/-0.005 mm, wherein the normalizing temperature is 850-900 ℃.

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

[ Table 3]

Here, the hot-rolled coils obtained after the normalizing step in examples 1 to 3 were subjected to a microscopic metallographic structure examination, and it was found that the structure of each example was a completely equiaxed ferrite structure and was uniform. In addition, the surface quality of the pickled steel sheets in comparative examples 1 to 3 and examples 1 to 3 was good. In examples 1 to 3, the thickness of the hot-rolled coil before the acid continuous rolling was 3.00mm, which was 2.50mm higher than that of comparative examples 1 to 3, and thus the actual production efficiency of examples 1 to 3 was improved.

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 the finished product, the low-temperature constant-speed production of the embodiment 1-3 is carried out; and comparative examples 1 to 3 have high annealing temperature and reduced head-to-tail speed. Wherein the annealing temperature 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.

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]

The results of testing the non-oriented silicon steel products obtained in comparative examples 1 to 3 and examples 1 to 3 are shown in Table 5.

[ Table 5]

As can be seen from the data in table 5:

(1) compared with the comparative example 1, the performance of the obtained non-oriented silicon steel finished product meets the iron loss P_1.5/50Less than or equal to 5.0W/kg, and magnetic induction intensity B₅₀₀₀The requirement of more than or equal to 1.75T; example 1 the hot rolling adopts low-temperature rolling and low-temperature coiling processes, and is matched with a low-temperature normalizing process to realize the stable through-coil magnetic performance and the fluctuation of the iron loss head, middle and tail under the constant-speed production of annealing<0.25W/kg, head-to-tail fluctuation of magnetic induction<0.015T；

(2) Compared with the comparative example 2, the performance of the obtained non-oriented silicon steel finished product meets the iron loss P_1.5/50Not more than 4.5W/kg, and magnetic induction intensity B₅₀₀₀The requirement of more than or equal to 1.73T; example 1 the hot rolling adopts low-temperature rolling and low-temperature coiling processes, and is matched with a low-temperature normalizing process to realize the stable through-coil magnetic performance and the fluctuation of the iron loss head, middle and tail under the constant-speed production of annealing<0.20W/kg, head-to-tail fluctuation of magnetic induction<0.015T；

(3) Compared with the comparative example 3, the performance of the obtained non-oriented silicon steel finished product meets the iron loss P_1.5/50Not more than 4.0W/kg, and magnetic induction intensity B₅₀₀₀The requirement of more than or equal to 1.71T; example 1 the hot rolling adopts low-temperature rolling and low-temperature coiling processes, and is matched with a low-temperature normalizing process to realize the stable through-coil magnetic performance and the fluctuation of the iron loss head, middle and tail under the constant-speed production of annealing<0.15W/kg, head-to-tail fluctuation of magnetic induction<0.015T；

(4) Meanwhile, in the embodiments 1 to 3, compared with the comparative examples, the contents of Si and Mn in the chemical components are both greatly reduced, Sn is not added in the steel making process (Sn contained in the finished product is inevitably introduced in molten iron or other alloys), the cost of the steel making alloy is reduced, the thickness of the hot rolled coil is increased, the production efficiency of hot rolling, normalizing and acid rolling is improved, the production cost is reduced by annealing at a low temperature and a constant speed, the normalizing process is increased without increasing the total production cost, and thus, under the condition of low overall alloy cost and production cost, 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 B₅₀₀₀Greatly increased and head, middle and tail magnetic induction intensity B₅₀₀₀The fluctuation is small.

In summary, it can be seen from the above examples 1 to 3 that the non-oriented silicon steel produced by the embodiment of the invention solves the problem of inconsistent coil-through magnetic properties of the low and medium grade non-oriented silicon steel without significantly increasing the production cost, and ensures good magnetic properties.