WO2012055215A1

WO2012055215A1 - Method for manufacturing non-oriented silicon steel with high-magnetic induction

Info

Publication number: WO2012055215A1
Application number: PCT/CN2011/072775
Authority: WO
Inventors: 王子涛; 王波; 谢世殊; 金冰忠; 马爱华; 邹亮; 朱雨华; 胡瞻源; 陈晓
Original assignee: 宝山钢铁股份有限公司
Priority date: 2010-10-25
Filing date: 2011-04-14
Publication date: 2012-05-03
Also published as: EP2508629A4; KR101404101B1; US20120285584A1; EP2508629A1; CN102453837A; CN102453837B; KR20120086343A; MX2012006680A; RU2527827C2; RU2012124187A; JP2013513724A

Abstract

A method for manufacturing non-oriented silicon steel with high-magnetic induction, includes the steps of: 1) smelting, casting smelting steel, secondary refining, and casting into a casting blank; wherein the non-oriented silicon steel composition by weigh percentage is composed of Si 0.1~1%, A1 0.005~1%, C 0.004% or less, Mn 0.10~1.50%, P 0.2% or less, S 0.005% or less, N 0.002% or less, Nb+V+Ti 0.006% or less, and balance iron; 2) heating to 1150~1200°C for hot rolling with the final rolling temperature of 830~900°C, and coiling at the temperature not less than 570°C; 3) cold rolling at a rolling reduction rate of 2-5% for leveling; 4) normalizing at the temperature not less than 950°C for 30~180 seconds; 5) acid pickling, and cold rolling at an accumulated rolling reduction rate of 70~80% after acid pickling; 6) annealing, heating to 800~1000°C in the speed of not less than 100 °C per second, keeping the temperature for 5~60 seconds, then slowly cooling to 600~750°C by 3~15 °C per second. According to the invention, on the premise of ensuring iron loss, the magnetic induction of non-oriented silicon steel can be improved at least 200 Gs.

Description

Method for manufacturing high magnetic induction non-oriented silicon steel

The present invention relates to a method for producing non-oriented silicon steel, and more particularly to a method for producing a high magnetic induction non-oriented silicon steel. Background technique

Non-oriented silicon steel is an important magnetic material and is widely used in various fields such as motors and compressors. In general, the silicon content is less than 6.5%, the aluminum content is less than 3%, C% is less than 0.1%, and contains less impurity elements. The hot rolling, normalizing and cold rolling processes are carried out, and the final annealing and coating of the insulating layer are carried out.

For non-oriented silicon steel, the performance indicators mainly include material iron loss, magnetic induction and magnetic anisotropy. The magnetic properties of non-oriented silicon steel are affected by various factors such as material composition, thickness, and heat treatment process.

In order to obtain ultra-high magnetic induction non-oriented silicon steel, a lower silicon content is generally used to lower the material resistivity, and at the same time, a high hot-rolled sheet is used to normalize the temperature, and the normalizing temperature is even as high as 1000 °C. However, due to the low content of silicon and aluminum, the recrystallized structure of the non-oriented silicon steel normalized plate is fine. The fine normalized structure makes the texture of the Okl } surface in the final annealed sheet low and the corresponding magnetic induction is low.

At the same time, the annealing process is also a key factor affecting the magnetic induction of the material. Appropriate soaking temperatures and holding times are usually used to obtain annealed sheets of appropriate grain size. If the soaking temperature is high, the holding time is long, and the grain of the annealed sheet is coarse, the texture of the (111 } plane will be enhanced, resulting in a decrease in magnetic inductance; but if the grain diameter is small, the hysteresis loss of the material is too large. Increased motor losses in end use.

When using rapid heating annealing, there is a strong Gaussian texture in the finished board compared to slow heating. On the other hand, the main texture component in the slow heating annealed finished sheet is (111 } <112>, while the (110 } <114>, { 001 } <120> and (111 } <110> components are weak. (Document: Jong-Tae PARK, Jerzy A. SZPUNAR Sang-Yun CHA Effect of Heating Rate on the Development of Annealing Texture in Nonoriented Electrical Steels ISIJ International, Vol. 43 (2003), No. 10, pp. 1611-1614 ) Therefore, the rapid heating annealing method can suppress the recovery process, and at the same time obtain the (110 } and (100 } surface texture cores to effectively improve the magnetic induction of the material. Summary of invention

The object of the present invention is to provide a method for manufacturing high magnetic induction non-oriented silicon steel, which can produce high magnetic induction non-oriented electrical steel by using hot rolling plate light pressing measures and rapid heating annealing of cold rolled plate under the premise of ensuring iron loss. .

In order to achieve the above object, the technical solution of the present invention is:

A method for manufacturing a high magnetic induction non-oriented silicon steel, comprising the following steps:

1) Smelting and casting

Non-oriented silicon steel chemical composition weight percentage: Si: 0.1~1%, A1: 0.005~1%, C≤0.004%, Mn: 0.10~1.50%, P<0.2%, S≤0.005%, N<0.002%,

Nb+V+Ti<0.006%; the rest are iron and unavoidable impurities; steel furnace in electric furnace or electric furnace, molten steel is re-refined and cast into a billet;

2) Hot rolling

The billet heating temperature is 1150 ° C ~ 1200 ° C, after hot soaking, hot rolling, hot rolling finishing temperature 830 ~ 900 ° C, under ≥ 570 temperature conditions;

3) leveling, cold rolling of the hot rolled sheet by 2 to 5%;

4) Normalization, a continuous annealing and normalization treatment of the cold-rolled hot-rolled sheet, the normalization temperature is not lower than 950 ° C, and the holding time is 30 to: 180 s;

5) pickling, cold rolling

The normalized plate is pickled, and then subjected to cold rolling of a cumulative reduction of 70 to 80% in multiple passes, and rolled into a cold-rolled plate of a target thickness.

6) Annealing, rapid heating annealing of cold-rolled cold-rolled sheet, heating rate ≥100°〇/8, heating to 800~1000°C, holding time 5~60s, then 3~15°C/s The cooling rate is slowly cooled to 600~750 °C _;

Further, the annealing atmosphere is (volume ratio 30%~70%) 3⁄4+ (volume ratio 70%~30%)

N ₂ , dew point ≤ -25 ° C.

The main factors affecting the magnetic induction strength B ₂₅ and B _5Q of non-oriented silicon steel are chemical composition and crystal texture. The amount of silicon, aluminum or manganese increases, the material resistivity increases, and B ₂₅ and B _5Q decrease. The ideal crystal texture is (100) [uvw] surface texture because it is isotropic and the hard magnetization direction [111] is not on the rolling surface. This single face texture is not actually available. There are generally (100) [011], (111) [112], (110) [001], (112) [011] and other texture components, of which (100) components The texture is only about 20%, which is basically a non-oriented chaotic texture, that is, magnetic isotropic. Therefore, adjusting the composition and improving the manufacturing process to make the (100) component strengthening and the (111) component weakening are important ways to increase the magnetic induction B ₂₅ and B _5Q .

The composition design of the present invention mainly considers the following points:

Si: soluble in ferrite to form a replacement solid solution, increase matrix resistivity, reduce iron loss, is the most important alloying element of electrical steel, but Si deteriorates magnetic induction. The present invention focuses on an ultra-high magnetic non-oriented silicon steel. Therefore, the Si content is low, 0.1 to 1%.

A1: It is also a resistivity-increasing element. It is soluble in ferrite to increase the matrix resistivity, coarsen the grain, and reduce the iron loss, but it also reduces the magnetic inductance. A1 content exceeding 1.5% will make smelting casting difficult, magnetic induction is lowered, and processing is difficult.

Mn: Compared with Si and A1, it can increase the electrical resistivity of steel and reduce the magnetic induction. However, Mn can reduce the iron loss and form a stable MnS with the inevitable inclusion S to eliminate the magnetic damage of S. Therefore, it is necessary to add a content of 0.1% or more. The Mn of the present invention is from 0.10% to 1.50%.

P: 0.2% or less, adding a certain amount of phosphorus to the steel can improve the workability of the steel sheet.

C, N, Nb, V, Ti: are all magnetic disadvantageous elements, and C ≤ 0.004% is required in the present invention.

S ≤ 0.005%, N < 0.002%, Nb + V + Ti < 0.006%, and the deterioration of magnetic properties is minimized.

The slab heating temperature should be lower than the solid solution temperature of the steel inclusions MnS and A1N. In the present invention, the heating temperature is set to 1150 ° C to 1200 ° C, the hot rolling finishing temperature is 830 to 900 ° C, and the coiling temperature is ≥ 570 ° C, which can ensure that the inclusions are not solid solution and obtain coarse hot rolled plate crystal. grain.

The proper leveling of the hot rolled sheet is a key factor for obtaining ultra high magnetic induction non-oriented silicon steel in the invention. The present invention is directed to a method for producing a non-oriented silicon steel having an ultra-high magnetic sensation. Therefore, in the chemical component, the content of silicon and aluminum is low. The lack of grain growth elements such as silicon and aluminum leads to the inability of the grains to grow normally during the normalization of the hot rolled sheet. At the same time, low-silicon non-oriented silicon steel is prone to recrystallization during hot rolling. Therefore, there are many fine equiaxed recrystallized grains in the hot-rolled sheet structure, and the rolled fiber structure is few. Applying a reduction ratio of 2 to 5% to the hot rolled sheet before the normalization can increase the internal deformation energy storage of the material, thereby making the recrystallization structure of the normalized sheet coarser. When the flattening reduction ratio is too large, the grain growth of the normalized plate is affected by the excessive internal defects of the hot rolled sheet.

The main purpose of hot-rolled sheet normalization and pre-annealing is to improve the grain structure and texture of the finished product. The results of research on low-silicon non-oriented electrical steel show that the coarsening of grain structure before cold rolling will weaken the {111} texture component of the cold-rolled sheet after final annealing, and the {Okl} texture component favorable for magnetic properties. Enhanced while The coarsening of the precipitates makes the crystal grains easier to grow, so that the magnetic inductance and the iron loss are improved. In the present invention, the high magnetic induction non-oriented silicon steel has a normalization temperature of not lower than 950 ° C and a holding time of 30 to 180 s.

(110 } Gaussian textured grains that are advantageous for magnetic properties are usually nucleated and grown in the cold-rolled trimming zone, and if the heating rate is slower, at lower temperatures, a recovery process occurs in the material, thereby reducing the material. In this case, the lattice distortion is greatly reduced. In this way, the probability of nucleation of Gaussian texture is greatly reduced. With rapid heating annealing, it can quickly pass through the temperature range where the texture is unfavorable, so that the favorable texture (Okl } texture is more Good development. Thereby the iron loss and magnetic induction are optimized. Slow cooling can reduce the internal stress of the annealed sheet and improve the magnetic properties. In the present invention, the cold-rolled sheet is subjected to rapid heating annealing, and the annealing heating rate is ≥100 °C/s. Warm up to 800~1000 °C, keep warm for 5~60s, then slowly cool to 600~750 °C at 3~15 °C/s.

The advantages of the invention are:

Compared with the conventional non-oriented silicon steel manufacturing method, the present invention can improve the magnetic induction of the non-oriented silicon steel by at least 200 gauss under the premise of ensuring iron loss. DRAWINGS

Figure 1 shows the relationship between the amount of flattening of the hot rolled sheet and the magnetic properties of the final annealed sheet. Detailed description of the invention

The present invention will be further described below in conjunction with the embodiments and the accompanying drawings.

Example 1

(1) Non-oriented silicon steel hot-rolled sheet, thickness 2.6mm, composition: Si 0.799%, A1 0.4282%, C 0.0016%, Mn O.26%, P<0.022%, S<0.0033%, N<0.0007%, Nb 0.0004%, V 0.0016%, Ti 0.0009%; the balance is iron and unavoidable impurities.

(2) Cold rolling the hot rolled sheet at a reduction ratio of 1 to 10%.

(3) Normalization treatment, normalized soaking temperature 970 °C, heat preservation 60s. The plate was then pickled and then cold rolled to a thickness of 0.5 mm.

(4) Rapid thermal annealing using a laboratory electric heating annealing furnace. The heating rate is 250 °C / s, the soaking temperature is 850 ° C, and the temperature is maintained for 13 s.

After the hot-rolled sheet is lightly pressed by 1 to 10%, the recrystallized structure of the normalized sheet is obviously enlarged, but the microstructure of the finished sheet is not much different. When the reduction is 4~6%, the magnetic properties of the finished board are optimal, and the magnetic induction B50 reaches 1.83T. The performance is shown in Table 1. The flattening reduction of the hot rolled sheet is related to the magnetic properties of the final annealed sheet. As shown in Figure 1.

Table 1. Magnetic properties of the final annealed sheet of non-oriented silicon steel

The microstructures of the normalized and final annealed sheets after flattening at different reduction rates were examined. It was found that after the cold-rolled sheets were slightly cold-rolled, the grains of the normalized sheets were significantly enlarged, and the grain size of the final annealed sheets did not change significantly. . The average grain size of the normalized and annealed sheets is shown in Table 2. The results have a good correspondence with the magnetic properties of the finished plate. As the grain of the normalized plate becomes larger, the { 111 } texture component is weakened after the final annealing of the cold rolled plate, and the {110} texture component favorable for magnetic properties is enhanced. , the final annealed sheet magnetic induction B50 optimized.

Table 2. Average grain diameter of normalized and annealed plates of non-oriented silicon steel

Example 2

(1) Non-oriented silicon steel hot-rolled sheet, thickness 2.6mm, composition: Si 1%, A1 0.2989%, C 0.0015%, Mn 0.297%, P 0.0572%, S 0.0027%, N 0.0009%, Nb 0.0005%, V 0.0015%, Ti 0.0011%; the balance is iron and unavoidable impurities.

(2) The hot rolled sheet is cold rolled at a reduction ratio of 4%.

(3) Normalization treatment, normalized soaking temperature 950 ° C, heat preservation 60s. The normalized sheet was then pickled and then cold rolled to a thickness of 0.5 mm. (4) Rapid heating annealing at different heating rates using a laboratory electric heating annealing furnace. The heating rate is 20 ° C / s, 150 ° C / s, 250 ° C / s, soaking temperature 960 ° C, holding for 13 s.

The properties of the final annealed sheet are shown in Table 3.

Table 3. Magnetic properties of the final annealed sheet of non-oriented silicon steel

As can be seen from Table 3, the effect of the annealing rate on the iron loss and magnetic induction of the annealed sheet. As the annealing rate increases, the iron loss decreases and the magnetic induction increases.

Claims

Claim

A method of manufacturing a high magnetic induction non-oriented silicon steel, comprising the steps of:

1) Smelting and casting

Non-oriented silicon steel chemical composition weight percentage: Si: 0.1~1%, A1: 0.005~1%, C≤0.004%, Mn: 0.10~1.50%, P<0.2%, S≤0.005%, N<0.002%, Nb +V+Ti<0.006%; the rest are iron and unavoidable impurities; steel in converter or electric furnace, molten steel is re-refined and cast into slab;

2) Hot rolling

The billet heating temperature is 1150 ° C ~ 1200 ° C, hot rolling after soaking, hot rolling final rolling temperature 830 ~ 900 ° C, under ≥ 570 temperature conditions;

3) leveling, cold rolling of the hot rolled sheet by 2 to 5%;

4) Normalization, a continuous annealing and normalization treatment of the cold-rolled hot-rolled sheet, the normalization temperature is not lower than 950 °C, and the holding time is 30~: 180s;

5) pickling, cold rolling

The normalized plate is pickled, and then subjected to cold rolling of a cumulative reduction of 70 to 80% in multiple passes, and rolled into a cold-rolled plate of a target thickness;

6) Annealing, rapid heating annealing of cold-rolled cold-rolled sheet, heating rate ≥100 °〇/8, heating to 800~1000 °C, holding time 5~60s, then 3~15 °C/s The cooling rate is slowly cooled to 600 to 750 °C.

2. The method of manufacturing a high magnetic induction non-oriented silicon steel according to claim 1, wherein the annealing atmosphere is: volume ratio 30% to 70% 3⁄4+volume ratio 70% to 30% N ₂ , dew point ≤-25 °C.