WO2013086900A1

WO2013086900A1 - Method for improving high-silicon steel preparation and processing capability by utilizing high-energy electrical pulse

Info

Publication number: WO2013086900A1
Application number: PCT/CN2012/083442
Authority: WO
Inventors: 梁永锋; 叶丰; 林均品; 周红婵; 房现石; 张来启; 郝国建
Original assignee: 北京科技大学
Priority date: 2011-12-13
Filing date: 2012-10-24
Publication date: 2013-06-20
Also published as: CN102417961B; CN102417961A

Abstract

A method for improving high-silicon steel preparation process capability by utilizing a high-energy electrical pulse. The silicon content in the high-silicon steel accounts for 4% to 7% (percent by mass), and the balance is iron, microelement boron and unavoidable impurity elements. During high-silicon steel sheet and strip plastic processing, a high-energy electrical pulse is applied to a deformation region, the frequency of the electrical pulse being 60 to 300 Hz, the pulse width being 10 to 300 μs, and the peak current density being 20 to 500 Α·mm-2; during a deformation process, the application of the high-energy electrical pulse significantly reduces the deformation resistance of the high-silicon steel sheet and strip and improves the plasticity of the high silicon steel sheet and strip.

Description

A method for improving the preparation and processing capability of high silicon steel by using high energy electric pulse

[0001] The present invention belongs to the technical field of metal material preparation, and relates to a method for improving the plastic working ability of a high silicon steel strip.

technical background

[0002] High silicon steel generally refers to silicon steel containing more than 3.5% silicon by weight (weight ratio, the same below). Compared with ordinary silicon steel (Si content <3.5%), high silicon steel has excellent magnetic properties, especially high silicon steel containing 6.5% silicon, its resistivity and magnetic permeability are significantly increased, coercive force and magnetocrystalline orientation. The heterogeneous performance is significantly reduced, has a magnetostriction coefficient of almost zero, and thus has the characteristics of low iron loss and low noise, and has a very important application background in the power electronics industry.

[0003] However, due to its high Si content, the processing capacity of high silicon steel is very poor, and the plasticity at room temperature is almost zero. It is difficult to process into a thin plate by the conventional rolling method, which limits the progress of its industrial application. A special processing method has been developed worldwide to prepare the alloy sheet (band), including chemical vapor deposition (CVD) (Y. Takada, et al., Journal of Applied Physics, 64 (1988), 5367-5369 ), rapid solidification method (KI Arai, H. Tsutsumitake and K. Ohmori, Transactions of the Japan Institute of Metals, 25 (1984), 855-862·), spray deposition method (C. Bolfarini, et al., Journal of Magnetism and Magnetic Materials, 320 (2008), e653-e656), direct powder rolling (R. Li, et al., Journal of Magnetism and Magnetic Materials, 281 (2004), 135-139·), special Rolling method (Υ· Liang, et al., Frontiers of Materials Science in China, 3 (2009), 329-332.) and the like. However, since the room temperature plasticity problem of the alloy has not been effectively solved, subsequent processing is difficult, and it is difficult to form a large-scale production. Therefore, it is very important to further improve the preparation ability of high-silicon steel, especially at room temperature to improve the plasticity of the material.

[0004] Electropulsing is an unsteady current field generated by a capacitor or an intermittent power source, which is a process of changing a voltage in a short time. Modern electric pulse technology is increasingly developing towards high frequency and high energy, and has a wide range of applications in the field of materials. The main operating principles are: high energy Joule heating effect, electroplastic effect.

Summary of the invention

[0005] It is an object of the present invention to provide a method for improving the processing properties of high silicon steel, for silicon containing A high-silicon steel sheet (belt) with a volume of 4 to 7% is used to improve the processing capacity of the thin plate (belt) by applying a high-energy electric pulse during the process of deformation.

[0006] A method for improving the preparation and processing capability of high-silicon steel by using high-energy electric pulse, the silicon content of the high-silicon steel is 4-7% (mass%), and the rest is iron, trace element boron and unavoidable impurity elements. During the plastic processing of high-silicon steel strip, a high-energy electric pulse is applied to the deformed region, the electric pulse frequency is 60-300HZ, the pulse width is 10-300 s, the peak current density is 20-500A · mm- ² , and high-energy electric pulse is applied during the deformation process. Significantly reduce the deformation resistance of the high-silicon steel strip, and greatly improve the plastic processing capability of the strip.

[0007] The high silicon steel strip has a thickness of 0.1-2 mm and a boron element content of 0-1000 ppm.

[0008] The application of high-energy electric pulse can effectively reduce the flow stress during the deformation process of the high-silicon steel material, and at the same time improve its plasticity, which is beneficial to the deformation process. High-silicon steel applies high-energy electric pulse during deformation. Due to the interaction of pulse current and dislocations in the material, the dislocation motion resistance decreases, resulting in a decrease in flow stress and an increase in plasticity. At the same time, due to the generation of Joule heat, the temperature of the material itself increases, which also causes the flow stress to decrease and the plasticity to increase. During the process of deformation, the microstructure of high-silicon steel materials will also change. Compared with no high-energy electric pulse, the recrystallization process is more likely to occur. The work hardening does not become obvious or even disappear during the deformation process. Therefore, the material can be compared. Multi-pass large strain deformation without intermediate annealing.

[0009] For example, high-power electric pulse is applied during the stretching process of high-silicon steel, and the surface temperature of the material during the tensile process is measured at a strain rate of 10 - ³ s - a pulse frequency of 120 Hz, a pulse width of 70 s, and a peak current density of 130 A · ηιηι - ² . At 175 ° C, the stress-strain curve is shown in Figure 1, expressed as (175 ° CE). Figure 1 also lists the unheated pulse, high tensile steel sheet at room temperature (RT), 50 ° C, 100 ° C, 150 ° C, 200 ° C, 250 ° C when stretched under normal heating conditions. stress-strain curve. It can be seen from the figure that the high silicon steel sheet has almost zero plasticity at room temperature stretching conditions and breaks during the elastic deformation stage. After the application of high-energy electrical pulses, the plasticity of the high-silicon steel is improved. At the same time, compared with the deformation of high silicon steel during ordinary heating, the yield strength of high silicon steel is significantly reduced after applying high energy electric pulse. It can be seen that the high energy electric pulse can improve the plasticity of the high silicon steel sheet while reducing the flow stress.

[0010] When the electric pulse parameter is 120 Hz, the pulse width is 70 s, the peak current density is 130 A · mm - ² , and the strain rate is 10 - ¹ , the flow stress of the material is further reduced and the plasticity is further improved during the tensile deformation process. The stress-strain curve is shown in Figure 2. The surface temperature of the material during this process was 350 °C. Keeping the strain rate constant, further increasing the peak current density, the surface temperature of the material is increased to 500 ° C, and the stress-strain curve is shown in Figure 3. During the stretching process shown in Figure 3, the high-energy pulse current is turned off for a few seconds and the stress is found. The book value has increased significantly. Continue to apply high energy electrical pulses and the stress value decreases rapidly. The rapid increase and decrease of the stress value in Figure 3 reflects the effect of high-energy electrical pulse on the flow stress value during deformation of the material.

[0011] The application of high-energy electrical pulses during the deformation of high-silicon steel significantly reduces its flow stress and increases its ductility. The advantages of the invention are:

For high silicon steel materials, it is considered to be difficult to prepare for processing due to poor plasticity at room temperature and high hardness. The present invention applies a high-energy electrical pulse to the metal section of the deformation zone during the deformation process of the high-silicon steel, thereby significantly reducing the strength and improving the plasticity thereof. This method improves the plasticity of the material, makes the preparation of the material possible, and at the same time eliminates the work hardening during the deformation process, so that the deformation process can be continuously performed, thereby omitting the intermediate annealing and improving the production efficiency. The method can be applied to the deformation process of rolling, drawing and the like of high silicon steel, and has broad engineering application prospects.

DRAWINGS

[0012] FIG. 1 Comparison of high energy electric pulse (175 ° C-E) applied during tensile deformation of high silicon steel and ordinary tensile deformation (room temperature, stretching during heating)

Fig. 2 Tensile curve of high silicon steel, applying high energy electric pulse, frequency: 120Hz, peak current density: 130A -mm" ² , strain rate: 10 - V ¹ , measuring deformation temperature: 35CTC

High silicon steel tensile curve in FIG. 3, the high energy electrical pulse is applied, frequency: 120Hz, peak current density: 172A -mm ^"2, strain rate: 10-V ^1, measuring the deformation temperature:. 500 ° C high energy electrical pulse modification disconnect The pulse continues to be applied after a few seconds.

detailed description

[0013] For a silicon content of 4-7%, a high silicon steel having a boron content of 0-1000 ppm, the thickness of the strip material is 0.1-2 mm, and the method of applying a high-energy electric pulse during the tensile deformation process is used to improve the deformability, and the specific embodiment As follows: Example 1

For high silicon steel sheets containing 4% silicon and no boron, the thickness is 2mm, and the tensile rate Is- ^ is applied during the deformation process. The electrical pulse parameters are: frequency 300Hz, pulse width 150 s, peak current density 400A * mm- ² , the material temperature rises obviously during the deformation process, the stress decreases obviously, and the deformation is easier to carry out.

[0014] Example 2

For a silicon-containing 5%, high-silicon steel sheet containing 150 ppm of boron, the thickness is 1 mm, the tensile rate is 10 - V ¹ , and a high-energy electric pulse is applied during the deformation. The electric pulse parameters are: frequency 200Hz, pulse width 100 s, peak current density 280Α · mm- ² , material temperature rises obviously during deformation, stress decreases obviously, deformation is easier to enter Explain the book line.

[0015] Example 3

For a silicon-containing steel sheet containing 6.5% silicon and 150 ppm boron, the thickness is 0.3 mm, and the tensile rate is 10 - a high-energy electric pulse is applied during the deformation. The electrical pulse parameters are: frequency 120Hz, pulse width 70 s, peak current density 130A · ηιηι- ² , the material temperature rises to 350 °C during deformation, the flow stress remains below 600Mpa, the stress decreases obviously, as shown in Figure 2 Show that the deformation is easier to carry out.

[0016] Example 4

For high silicon steel sheets containing 6.5% silicon and 300 ppm boron, the thickness is 0.3 mm, and the tensile rate is 10 - high energy pulses are applied during the deformation process. The electrical pulse parameters are: frequency 120Hz, pulse width 70 s, peak current density 172A · mm- ² , material temperature increases to 500 °C during deformation, flow stress remains below 50MPa, stress reduction is obvious, as shown in Figure 3. Show. During the stretching process, the high energy pulse current was turned off for a few seconds and it was found that the stress value increased significantly. Continue to apply high energy electrical pulses and the stress value decreases rapidly. The rapid increase and decrease of the stress value reflects the influence of the high energy electric pulse on the flow stress value during the deformation of the material. Applying a high-energy electrical pulse makes the deformation easier.

[0017] Example 5

For a silicon-containing 7% high-silicon steel sheet containing 1000 ppm of boron, the thickness is 0.1 mm, and the tensile rate is 10 - ³ s - a high-energy electric pulse is applied during the deformation. The electric pulse parameters are: frequency 100Hz, pulse width 50 s, peak current density 50Α · mm- ² , material temperature rises obviously during deformation, stress decreases obviously, and deformation is easier to carry out.

Claims

Claim

1. A method for improving the preparation and processing capability of high-silicon steel by using high-energy electric pulse. The content of silicon content in high-silicon steel is 4-7%, and the rest is iron, trace element boron and inevitable impurity elements, which are characterized by high-silicon steel sheets. During the plastic processing of the strip, a high-energy electric pulse is applied to the deformed region, the electric pulse frequency is 60-300 Hz, the pulse width is 10-300 μs, the peak current density is 20-500 A · mm ² , and the application of high-energy electric pulse during the deformation process is significantly lowered. The deformation resistance of the silicon steel strip greatly improves the plastic working ability of the strip.

2. The method for improving the preparation and processing capability of high silicon steel by using high energy electric pulse according to claim 1, characterized in that the thickness of the high silicon steel strip is 0.1-2 mm.

3. The method for improving the preparation and processing capability of high silicon steel by using high energy electric pulse according to claim 1, characterized in that the content of boron element in the high silicon steel is 0-1000 ppm.