A method for improving lambda fiber texture in non-oriented silicon steel

Abstract

The present invention discloses a method for improving the λ fiber texture in high-grade non-oriented silicon steel prepared by ultra-thin strip process. The high-Si non-phase-change non-oriented silicon steel prepared by ultra-thin strip process is subjected to compression deformation and heat treatment at the same time, and the strain rate is regulated, so that the original cast structure evolves into a λ composite structure, and a Cube texture and a rotated Cube texture are generated in the original simple λ texture, while the formation of γ texture is reduced. The present invention can control the degree of compression deformation by regulating the strain rate to control the strength and transformation of each texture, so as to implement artificial control of the crystal preferential orientation behavior in the process of evolving from the original cast structure to the λ composite structure, optimize the process of preparing non-oriented silicon steel by ultra-thin strip production line; the control range of texture strength is flexible, which is beneficial to the application of actual production. It provides a basic method for optimizing the λ fiber texture by controlling the crystal preferential orientation behavior by regulating the strain rate.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a method for improving lambda fiber texture in non-oriented silicon steel. Background Art

[0002] Electrical steel is mainly used in the cores of various motors and transformers. It is an important soft magnetic alloy that is indispensable in the power, electronics and military industries. As the country's requirements for energy conservation and emission reduction are increasing, this is a great challenge to traditional metallurgy. At the same time, society's requirements for the energy efficiency of transformers, motors, etc. are getting higher and higher, which is bound to increase the demand for high-grade non-oriented silicon steel. One of the most important factors affecting the performance of electrical steel is texture. At present, the non-oriented silicon steel actually produced in industry is mainly γ texture, and λ texture accounts for less than 10%. The type and strength of the texture of the steel sample are affected by the composition and process parameters of the experimental steel. Therefore, it is necessary to study the influence of the composition of the molten steel and the process parameters on the texture.

[0003] The ultra-thin strip process greatly reduces energy consumption, gas emissions, and production line investment. In addition, sub-rapid solidification creates the preferential growth of {100}, and the subsequent hot rolling process will affect the inheritance and evolution of the λ({100}) texture. There have been many studies on the hot rolling process, such as the starting temperature, final rolling temperature, curling temperature, and reduction rate. However, there are few studies on the effect of strain rate on the organization and texture in this process, and there is still a lot of room for improvement. Therefore, it is necessary to invent a method for improving the λ organization and texture in the preparation of high-grade non-oriented silicon steel by ultra-thin strip process by regulating the strain rate.

[0004] At present, the development of strain rate is still in the research of medium and high carbon steel, and the influence of strain rate is rarely considered in factory production, and it is difficult for on-site hot rolling mills to regulate the strain rate. The present invention will use Gleeble-3800 to simulate the hot rolling compression process, and control the organization and texture of the steel sample by regulating the strain rate, so as to achieve the goal of improving the λ fiber texture in the high-grade non-oriented silicon steel prepared by the ultra-thin strip process by regulating the strain rate. Summary of the invention

[0005] The purpose of the present invention is to provide a method for improving the λ fiber texture in high-grade non-oriented silicon steel prepared by ultra-thin strip process, by simulating hot rolling of high-grade non-oriented silicon steel cast strip prepared by ultra-thin strip process, and regulating the strain rate in the process to obtain Cube texture and rotational Cube texture with higher strength, which has achieved the high requirements for the magnetic properties of non-oriented silicon steel, and achieved cost saving and efficiency improvement in actual production.

[0006] The technical solution for achieving the purpose of the present invention is as follows:

[0007] According to a first aspect of the present invention, a method for improving lambda fiber texture in non-oriented silicon steel is disclosed, the method comprising the following steps:

[0008] Step 1: smelting molten steel:

[0009] The chemical composition of molten steel of non-oriented silicon steel is calculated in mass percentage:

[0010] C≤0.003%, Si: 2.3~3.5%, Al: 0.003~0.8%, Mn: 0.2~0.4%, P: 0.003~0.03%, S: 0.001~0.003%, the rest is Fe and unavoidable impurities;

[0011] Step 2 Strip Casting:

[0012] The casting strip is prepared by ultra-thin strip process with a thickness of 1.7 to 2.0 mm;

[0013] Step 3: Processing the sample:

[0014] The size of the processed steel sample is: φ = 6mm ± 1mm, the height is 1.7 ~ 2.0mm, so that the two sides of the steel that bear the force are polished and smooth to ensure that the strain state of plane strain is achieved when the sample is compressed;

[0015] Step 4: Hot rolling deformation:

[0016] The sample processed in step 3 is placed between two fixtures, the temperature state of the sample is detected in real time, and the thermal deformation simulator is started to simulate the hot rolling process parameters of the sample, so that the fixture compresses and deforms the sample processed in step 3.

[0017] According to the method for improving the λ fiber texture in non-oriented silicon steel of the present invention, preferably, in step 4, a heat treatment is first performed, and then a simulated hot compression deformation is started, and a cooling treatment is performed after the deformation.

[0018] According to the method for improving the λ fiber texture in non-oriented silicon steel of the present invention, preferably, the strain rate of the hot compression deformation is controlled to be 0.01-5 / s.

[0019] According to the method for improving the lambda fiber texture in non-oriented silicon steel of the present invention, preferably, the minimum deformation temperature of the hot compression deformation is controlled at 700-1000°C.

[0020] According to the method for improving λ fiber texture in non-oriented silicon steel of the present invention, preferably, the range of compression deformation degree for controlling texture in processed steel is controlled to be ε=25%-55%, so that the organization changes to form deformation bands and substructures.

[0021] According to the method for improving the λ fiber texture in non-oriented silicon steel of the present invention, preferably, within the control range of the degree of compression deformation, within the temperature range of the hot rolling treatment, a compression process with different strain rates is carried out, and the strain rate is controlled within the range of 0.01 / s to 5 / s to control the deformation of the organization and the transformation of the texture.

[0022] According to the method for improving λ fiber texture in non-oriented silicon steel of the present invention, preferably, step 4 further comprises: regulating the strain rate during hot rolling so that the original as-cast structure evolves into a λ composite structure.

[0023] According to the method for improving the λ fiber texture in non-oriented silicon steel of the present invention, preferably, the volume fraction of the λ composite structure is controlled to be 28-48%.

[0024] According to the method for improving λ fiber texture in non-oriented silicon steel of the present invention, preferably, step 4 further comprises: generating a Cube texture and a rotated Cube texture in the original simple λ texture to reduce the formation of γ texture.

[0025] According to a second aspect of the present invention, a high-grade non-oriented silicon steel is disclosed, wherein the high-grade non-oriented silicon steel is produced by the above method. The high-grade non-oriented silicon steel does not undergo phase transformation and has a pure ferrite structure.

[0026] Beneficial technical effects

[0027] Compared with the prior art, the technical advantages and beneficial technical effects of the present invention are briefly summarized as follows:

[0028] The compression direction (CD) in the present invention corresponds to the normal direction (ND) during hot rolling, and the direction of the contact surface between the fixture and the sample corresponds to the rolling direction (RD) during hot rolling.

[0029] During the hot rolling process, the strain state of the sample area other than the surface layer is approximately a plane strain state, and the texture produced by the sample is the texture under the plane strain state. Therefore, in order to simulate the hot rolling texture of the sample, the strain state of plane strain needs to be achieved.

[0030] For the sample plate, the organization and texture are controlled by adjusting the strain rate, and then the crystal preferential orientation behavior in the process of transforming from the original cast texture to the Cube texture and rotating the Cube texture is artificially controlled, so as to optimize the hot rolling process of the steel.

[0031] The present invention also uses a Gleeble-3800 thermal simulator to accurately control temperature, deformation parameters and strain rate, thereby achieving accurate, efficient and economical simulation of the hot-rolled texture of the sample. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly introduce the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings of the embodiments. Obviously, the drawings in the following description only relate to some implementation cases of the present invention, and are not intended to limit the present invention.

[0033] Figure 1 It is a process diagram of simulating hot rolling of the embodiment of the present invention and the comparative example,

[0034] Where: s is the strain rate; T is the final rolling temperature; ε is the strain rate;

[0035] Figure 2 The sample texture is obtained by using EBSD (point backscatter diffraction) to detect the sample texture in Example 1 of the present invention. ODF (three-dimensional orientation distribution function) diagram;

[0036] Figure 3 The sample texture is obtained by using EBSD (point backscatter diffraction) to detect the sample texture in Example 2 of the present invention. ODF (three-dimensional orientation distribution function) diagram;

[0037] Figure 4 The sample texture is obtained by using EBSD (point backscatter diffraction) to detect the sample texture in Example 3 of the present invention. ODF (three-dimensional orientation distribution function) diagram;

[0038] Figure 5 The sample texture was obtained by using EBSD (point backscatter diffraction) to detect the sample texture in Comparative Example 1. ODF (three-dimensional orientation distribution function) diagram;

[0039] Figure 6 The sample texture was obtained by using EBSD (point backscatter diffraction) to detect the sample texture in Comparative Example 2. ODF (three-dimensional orientation distribution function) diagram;

[0040] Figure 7 Some important orientations in electrical steel The position in the ODF graph. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one of ordinary skill in the art to which the present invention belongs.

[0043] Example 1

[0044] The physical simulation method of the steel plate hot rolling texture of this embodiment is carried out according to the following steps:

[0045] Step 1 Smelting: The chemical composition of the experimental steel is as follows according to mass percentage:

[0046] C: 0.0015%, Si 3.15%, Mn 0.276%, P 0.0204%, S 0.001%, Al 0.6%, the balance is Fe, the casting strip is prepared by ultra-thin strip process, the thickness is 1.8mm;

[0047] Step 2 Processing: The size of the processed steel sample is: φ = 6mm ± 1mm, the height is 1.8mm, and the two stressed sides of the steel are polished and smoothed to ensure that the strain state of plane strain is achieved when the sample is compressed;

[0048] Step 3 Hot rolling: Place the sample processed in step 2 between two fixtures, detect the temperature of the sample in real time, start the Gleeble-3800 thermal deformation simulator, and simulate Figure 1 The sample hot rolling process parameters in the step 2 are used to make the fixture compress and deform the sample processed in step 2. First, a heat treatment is performed, and then simulated hot compression deformation is started. The strain rate is 0.01 / s, the temperature of the compression deformation process is controlled at 950°C, the deformation amount is 30%, and at the same time, the temperature is cooled at a certain rate after deformation.

[0049] After the experiment, the sample was mechanically polished and lightly etched to remove stress. Then, a scanning electron microscope equipped with an EBSD device was used to perform EBSD detection at the same position. The measurement area was 398μm×275μm, and the step length was 5μm. The EBSD test results The ODF diagram is as follows Figure 2 As shown, compared Figure 2 and Figure 7 It can be seen that the obtained texture is composed of strong λ fiber texture and rotating Cube{100} <011> Mainly, with volume fractions of 28.8% and 5% respectively, which is a texture beneficial to the performance development in non-oriented silicon steel.

[0050] It can be seen from the above EBSD experiment that, under the premise of meeting a certain strain rate, the present invention realizes the formation of the rotational Cube texture and the strengthening of the λ fiber texture, providing guidance for the subsequent realization of an efficient and economical process.

[0051] Example 2

[0052] The physical simulation method of the steel plate hot rolling texture of this embodiment is carried out according to the following steps:

[0053] Step 1 Smelting: The chemical composition of the experimental steel is as follows according to mass percentage:

[0054] C 0.0015%, Si 3.15%, Mn 0.276%, P 0.0204%, S 0.001%, Al 0.6%, the balance is Fe, the casting strip is prepared by ultra-thin strip process, and the thickness is 1.8 mm;

[0055] Step 2 Processing: The size of the processed steel sample is: φ = 6mm ± 1mm, the height is 1.8mm, and the two stressed sides of the steel are polished and smoothed to ensure that the strain state of plane strain is achieved when the sample is compressed;

[0056] Step 3 Hot rolling: Place the sample processed in step 2 between two fixtures, detect the temperature of the sample in real time, start the Gleeble-3800 thermal deformation simulator, and simulate Figure 1 The sample hot rolling process parameters in the step 2 are used to make the fixture compress and deform the sample processed in step 2. First, a heat treatment is performed, and then simulated hot compression deformation is started. The strain rate is 0.1 / s, the temperature of the compression deformation process is controlled at 950°C, the deformation amount is 30%, and at the same time, the temperature is cooled at a certain rate after deformation.

[0057] After the experiment, the sample was mechanically polished and lightly etched to remove stress. Then, a scanning electron microscope equipped with an EBSD device was used to perform EBSD detection at the same position. The measurement area was 398μm×275μm, and the step length was 5μm. The EBSD test results The ODF diagram is as follows Figure 3 As shown, compared Figure 3 and Figure 7 It can be seen that the obtained texture is composed of strong λ fiber texture, Cube texture and rotated Cube{100} <011> The volume fractions are 48.7%, 33.6% and 9.86% respectively, and a {112} texture is formed which is conducive to Cube nucleation.

[0058] Example 3

[0059] The physical simulation method of the steel plate hot rolling texture of this embodiment is carried out according to the following steps:

[0060] Step 1 Smelting:

[0061] The chemical composition of the experimental steel is as follows according to mass percentage: C 0.0022%, Si 2.5%, Al 0.006%, Mn 0.276%, and the rest is Fe and unavoidable impurities; the casting strip is prepared by ultra-thin strip process, with a thickness of 1.8 mm;

[0062] Step 2 Processing: The size of the processed steel sample is: φ = 6mm ± 1mm, the height is 1.8mm, and the two stressed sides of the steel are polished and smoothed to ensure that the strain state of plane strain is achieved when the sample is compressed;

[0063] Step 3 Hot rolling: Place the sample processed in step 2 between two fixtures, detect the temperature of the sample in real time, start the Gleeble-3800 thermal deformation simulator, and simulate Figure 1 The sample hot rolling process parameters in the step 2 are used to make the fixture compress and deform the sample processed in step 2. First, a heat treatment is performed, and then simulated hot compression deformation is started. The strain rate is 0.01 / s, the temperature of the compression deformation process is controlled at 950°C, the deformation amount is 30%, and at the same time, the temperature is cooled at a certain rate after deformation.

[0064] After the experiment, the sample was mechanically polished and lightly etched to remove stress. Then, a scanning electron microscope equipped with an EBSD device was used to perform EBSD detection at the same position. The measurement area was 398μm×275μm, and the step length was 5μm. The EBSD test results The ODF diagram is as follows Figure 4 As shown, compared Figure 4 and Figure 7 It can be seen that the obtained texture is composed of strong λ fiber texture and rotating Cube{100} <011> Mainly, the volume fractions are 48% and 44.4% respectively.

[0065] Comparative Example 1

[0066] The physical simulation method of the steel plate hot rolling texture of this embodiment is carried out according to the following steps:

[0067] Step 1: Smelting: The chemical composition of the experimental steel is as follows: C 0.0015%, Si 3.15%, Mn 0.276%, P 0.0204%, S 0.001%, Al 0.6%, and the balance is Fe. The casting strip is prepared by ultra-thin strip process with a thickness of 1.8 mm.

[0068] Step 2 Processing: The size of the processed steel sample is: φ = 6mm ± 1mm, the height is 1.8mm, and the two stressed sides of the steel are polished and smoothed to ensure that the strain state of plane strain is achieved when the sample is compressed;

[0069] Step 3 Hot rolling: Place the sample processed in step 2 between two fixtures, detect the temperature state of the sample in real time, start the Gleeble-3800 thermal deformation simulator, and simulate Figure 1 The sample hot rolling process parameters in the step 2 are used to make the fixture compress and deform the sample processed in step 2. First, a heat treatment is performed, and then simulated hot compression deformation is started. The strain rate is 5 / s, the temperature of the compression deformation process is controlled at 950°C, the deformation amount is 30%, and at the same time, the temperature is cooled at a certain rate after deformation.

[0070] After the experiment, the sample was mechanically polished and lightly etched to remove stress. Then, a scanning electron microscope equipped with an EBSD device was used to perform EBSD detection at the same position. The measurement area was 398μm×275μm, and the step length was 5μm. The EBSD test results The ODF diagram is as follows Figure 5 As shown, compared Figure 5 and Figure 7 It can be seen that the obtained texture includes weak λ fiber texture and stable α fiber texture, and the λ texture accounts for 9.57%, which will reduce the performance of subsequent non-oriented silicon steel.

[0071] Comparative Example 2

[0072] The physical simulation method of the steel plate hot rolling texture of this embodiment is carried out according to the following steps:

[0073] Step 1 Smelting:

[0074] The chemical composition of the experimental steel is as follows according to mass percentage:

[0075] C 0.0022%, Si 2.5%, Al 0.006%, Mn 0.276%, the rest is Fe and inevitable impurities; the casting strip is prepared by ultra-thin strip process, with a thickness of 1.8mm;

[0076] Step 2 Processing: The size of the processed steel sample is: φ = 6mm ± 1mm, the height is 1.8mm, and the two stressed sides of the steel are polished and smoothed to ensure that the strain state of plane strain is achieved when the sample is compressed;

[0077] Step 3 Hot rolling: Place the sample processed in step 2 between two fixtures, detect the temperature state of the sample in real time, start the Gleeble-3800 thermal deformation simulator, and simulate Figure 1 The sample hot rolling process parameters in the step 2 are used to make the fixture compress and deform the sample processed in step 2. First, a heat treatment is performed, and then simulated hot compression deformation is started. The strain rate is 1 / s, the temperature of the compression deformation process is controlled at 950°C, the deformation amount is 30%, and at the same time, the temperature is cooled at a certain rate after deformation.

[0078] After the experiment, the sample was mechanically polished and lightly etched to remove stress. Then, a scanning electron microscope equipped with an EBSD device was used to perform EBSD detection at the same position. The measurement area was 398μm×275μm, and the step length was 5μm. The EBSD test results The ODF diagram is as follows Figure 6 As shown, compared Figure 6 and Figure 7 It can be seen that the obtained texture is mainly composed of strong λ fiber texture, with the λ texture accounting for 20.5%, and there is no Cube and rotated Cube.

[0079] It can be seen from the above EBSD experiment that, under the premise of meeting a certain strain rate, the present invention realizes the formation of the rotational Cube texture and the strengthening of the λ fiber texture, providing guidance for the subsequent realization of an efficient and economical process.

[0080] It can be seen from the above EBSD experiment that, under the premise of meeting a certain strain rate, the present invention realizes the formation and strengthening of Cube texture and rotational Cube texture, providing guidance for the subsequent realization of efficient and economical processes.

[0081] The above description is only a specific implementation of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for improving lambda fiber texture in non-oriented silicon steel, characterized in that: The method comprises the following steps: Step 1: smelting molten steel: The chemical composition of molten steel of non-oriented silicon steel is calculated in mass percentage: C: ≤0.003%, Si: 2.5~3.5%, Al: 0.003~0.8%, Mn: 0.2~0.4%, P: 0.003-0.03%, S: 0.001-0.003%, the rest is Fe and unavoidable impurities; Step 2 Strip Casting: The casting strip is prepared by ultra-thin strip process with a thickness of 1.7 to 2.0 mm; Step 3: Processing the sample: The size of the processed steel sample is: φ = 6mm ± 1mm, the height is 1.7 ~ 2.0mm, so that the two sides of the steel that bear the force are polished and smooth to ensure that the strain state of plane strain is achieved when the sample is compressed; Step 4: Hot rolling deformation: Place the sample processed in step 3 between two fixtures, perform heat treatment first, detect the temperature state of the sample in real time, start the thermal deformation simulator, simulate the hot rolling process parameters of the sample, make the fixture compress and deform the sample processed in step 3, and perform cooling treatment after deformation. Among them, the strain rate of the hot compression deformation in step 4 is controlled to be 0.01-0.1 / s, the minimum deformation temperature is controlled to be 700-1000°C, and the range of compression deformation degree is controlled to be ε=25%-55%, so that the original cast structure evolves into a λ composite structure containing Cube texture and rotated Cube texture, forming deformation bands and substructures, and the volume fraction of the λ composite structure is controlled to be 28-48%.

2. The method for improving the lambda fiber texture in non-oriented silicon steel according to claim 1, characterized in that: In step 4, the strain rate of the hot compression deformation is controlled to be 0.01 / s.

3. The method for improving lambda fiber texture in non-oriented silicon steel according to claim 1, characterized in that: In step 4, the strain rate of the thermal compression deformation is controlled to be 0.1 / s.

4. The method for improving lambda fiber texture in non-oriented silicon steel according to claim 1, characterized in that: The minimum deformation temperature of thermal compression deformation is controlled at 700-950°C.

5. The method for improving λ fiber texture in non-oriented silicon steel according to claim 1, characterized in that: The range of the degree of compression deformation for controlling the texture in the processed steel is controlled to be ε=30% to 55%.

6. The method for improving lambda fiber texture in non-oriented silicon steel according to any one of claims 1 to 5, characterized in that: The volume fraction of the λ composite structure is controlled to be 28.8%.

7. A high grade non-oriented silicon steel, characterized in that: The high-grade non-oriented silicon steel is produced by the method according to any one of claims 1 to 6, and the high-grade non-oriented silicon steel does not undergo phase change and has a pure ferrite structure.

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