MX2012006680A

MX2012006680A - Method for manufacturing non-oriented silicon steel with high-magnetic induction.

Info

Publication number: MX2012006680A
Application number: MX2012006680A
Authority: MX
Inventors: Bo Wang; Zitao Wang; Shishu Xie; Bingzhong Jin; Aihua Ma; Liang Zou; Yuhua Zhu; Zhanyuan Hu; Xiao Chen
Original assignee: Baoshan Iron & Steel
Priority date: 2010-10-25
Filing date: 2011-04-14
Publication date: 2012-10-15
Also published as: KR20120086343A; EP2508629A1; RU2012124187A; KR101404101B1; US20120285584A1; EP2508629A4; JP2013513724A; CN102453837A; RU2527827C2; WO2012055215A1; CN102453837B

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 1150~1200Â°C for hot rolling with the final rolling temperature of 830~900Â°C, and coiling at the temperature not less than 570Â°C; 3) cold rolling at a rolling reduction rate of 2-5% for leveling; 4) normalizing at the temperature not less than 950Â°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 800~1000Â°C in the speed of not less than 100 Â°C per second, keeping the temperature for 5~60 seconds, then slowly cooling to 600~750Â°C by 3~15 Â°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

A PROCESS OF MANUFACTURING STEEL TO NON-ORIENTED SILICON WITH HIGH MAGNETIC INDUCTION FIELD OF THE INVENTION This invention relates generally to a non-oriented silicon steel manufacturing process, and in particular, to a non-oriented silicon steel manufacturing process with high magnetic induction.

BACKGROUND OF THE INVENTION Non-oriented silicon steel is an important magnetic material and widely used in the manufacture of various electrical machines, with compressors and so on. In general, it contains silicon with less than 6.5%, aluminum with less than 3%, carbon with less than 0.1% and other trace elements. The silicon steel manufacturing process includes the hot rolling, standardizing, cold rolling, finished annealing and insulation film coating process.

In reference to non-oriented silicon steel, the indices of the main properties include iron loss, magnetic induction and magnetic anisotropy. The magnetic properties of non-oriented silicon steel are very likely to be affected by various factors such as the compositions of the material, the thickness, the heat treatment process, and so on.

In order to obtain a non-oriented silicon steel with a super high magnetic induction, a common practice is to reduce the silicon content and thus reduce the electrical resistivity of the material, meanwhile, to adopt a higher standardization temperature for the laminated plate or hot rolled, for example, even up to 1000 ° C. However, because the contents of silicon and aluminum are much lower, the recrystallized structure of the normalized non-oriented silicon steel plate is very thin. The fine grain structure generated in the normalization will originate the texture of the surface. { Okl} of the annealed sheet finished to have a lower intensity, and accordingly, a lower magnetic induction.

Moreover, the annealing process is also a critical factor to affect the magnetic induction of the silicon steel. In order to make an annealed sheet having appropriately sized grains, a common practice is to employ an appropriate homogenization temperature and an appropriate homogenization or thermodifusion period. If the homogenization temperature is too high and the thermoforming period is too long, the crystal grains of the annealed silicon steel will be very coarse, the texture of the surface. { lll} it will intensify, and the magnetic induction of the blade will weaken; On the contrary, if the diameters of the grains are small, the loss of hysteresis of the material will be long, which will increase the electrical loss in the final use.

In the annealing process, compared to heating at a lower temperature rise rate, heating at a higher temperature rise rate will produce a very strong Gaussian texture. Meanwhile, heating at a lower temperature rise rate will result in the texture of the finished silicon steel product being composed of more components. { lll} (112) and fewer components. { mess} (114),. { 001.}. (120). { lll} (110). (See document: Jong-Tae PARK, Jerzy A. SZPUNAR Sang-Yun CHA Effect of heating Rate on the development of Annealing Texture in Non-oriented Electrical steels ISIJ International, Vol. 43 (2003), NO.10, pp. 1611 -1614). Therefore, in the annealing process, heating at a higher temperature rise rate can press the recovery and give a surface texture with. { 110.}. Y . { 100.}. in the core, and in such a way that the magnetic induction of the finished silicon steel product is effectively improved.

BRIEF DESCRIPTION OF THE INVENTION The object of the invention is to provide a non-oriented silicon steel manufacturing process with high magnetic induction, the manufacturing process is characteristic to include the measurements: laminate the hot rolled plate lightly and heat the laminated or cold rolled sheet quickly at an annealing temperature in order to obtain non-oriented silicon steel with high magnetic induction under the precondition of not increasing iron loss to the sheet.

In order to achieve the above objective, the manufacturing process of the invention of non-oriented silicon steel with high magnetic induction comprises the following procedures: 1) Cast and cast The chemical compositions of the non-oriented silicon steel, in percentage by weight, are: Si 0.1 ~ 1%, Al 0.005 ~ 1.0%, C < 0.004%, Mn = 0.10 - 1.50%, P < 0.2%, S < 0.005%, N < 0.002, Nb + V + Ti < 0.006%, and the rest is iron and inevitable inclusions; Non-oriented silicon steel is melted and treated with secondary refining in a converter or electric furnace, and then cast in a steel ingot; 2) Hot rolling The steel ingot is heated to a temperature of between 1150 ~ 1200 ° C, and maintained at the temperature for a certain time, and then hot-rolled on a steel plate at a finish-lamination temperature of 830 ~ 900 ° C; when it is cooled to a temperature > 570 ° C, the hot-rolled plate is wound; 3) Flattening The hot-rolled plate is cold rolled at a lamination compression ratio of 2 ~ 5%; 4) Normalization After being cold rolled, the hot rolled plate is continuously normalized in a time at a temperature not lower than 950 ° C, and maintained at the temperature for 30 ~ 18Os; 5) Pickling and Cold Rolling.

The normalized plate is pickled, and then successively cold-rolled several times at a compression rate by progressive or total rolling of 70 ~ 80% finally on a cold-rolled silicon steel sheet with the thickness of its finished product; 6) Annealing The cold rolled sheet is rapidly heated to a temperature between 800 ~ 1000 ° C at a temperature rise rate not lower than 100 ° C / s, and maintained at the temperature for 5 ~ 60s, subsequently cooled slowly to 600 ~ 750 ° C at a cooling speed of 3 ~ 15 ° C / s.

In the preferred embodiment, the Annealing atmosphere, by volume percentage, is H2 of 30% ~ 70% + N2 of 70% ~ 30%, the dew point = -25 ° C.

The main factors to have an effect on the intensity of the magnetic induction B25 and B50 of non-oriented silicon steel are the chemical compositions and the grain texture of the crystal. Higher silicon, aluminum and manganese contents will result in greater current resistivity and lower magnetic properties B25 and B50. The texture of the ideal crystal is the texture of the surface (100) [uvw] because it is isotropic and the hard magnetized direction is not on the laminated surface. In practice, it is impossible to achieve a unique surface texture of this kind. In general, there are texture components (100) [011], (111) [112], (110) [001], (112) [011] and so on, of which, the texture component (100) alone totals 20% or so and mainly corresponds to the unoriented disordered texture, that is, magnetic anisotropic. By means of this, changing the chemical compositions of the material and improving the manufacturing process in order to intensify the component (100) and weaken the component (111) is an important approach to raise the intensity of magnetic induction B25 and B50.

In the design of the composition of the invention, the following points are mainly taken into account: Yes: it is soluble in ferrite to form a solid substitution solution in order to increase the resistivity of the material and reduce the loss of iron, and thus, it is the most important alloying element of electric steel, but it is adverse to magnetic induction . The invention is intended for non-oriented silicon steel with high magnetic induction, therefore, the Si content is determined as low as 0.1 ~ 1%.

Al: It is also an element to increase the resistivity, and it is soluble in ferrite to increase the resistivity of the material and make the grains of crystals thicker and reduce the iron loss, but it will also reduce the magnetic induction. The content of more than 1.5% will make melting, casting and machining difficult and will reduce magnetic induction.

Mn: Like Si and Al, it will increase the resistivity of the steel and reduce the magnetic induction, but it is advantageous to reduce the loss of iron, and will react with the S of the composition to generate stable MnS in order to eliminate the adverse influence of S on magnetic property. Therefore, it is necessary to have a content of Mn of more than 0.1% in silicon steel. In the invention, the content of Mn is controlled within 0.10 ~ 1.50%.

P: To add P of a certain content in the steel compositions, the manufacturing capacity of the Silicon Steel can be improved, but the P content must be less than 0.2%.

C, N, Nb, V and Ti: are all elements adverse to the magnetic property. In the invention, it is controlled that C = 0.004%, S = 0.005%, N < 0.002, NB + V + Ti < 0.006% in order to minimize its adverse effect on the magnetic property.

The temperature of the heated slab or slab must be below the temperature of the solid solution of the MnS and A1N inclusions in the steel. In the invention, the heating temperature is adjusted to 1150 ~ 1200 ° C, the finished rolling temperature is adjusted to 830 ~ 900 ° C, and the winding temperature is adjusted not below 570 ° C, these temperatures can avoid the inclusions in the solid solution and make the hot-rolled plate have coarse grains.

In the invention, flattening the hot rolled plate properly is a key factor in achieving a non-oriented silicon steel with super high magnetic induction. The object of the invention is a manufacturing process of non-oriented silicon steel with super high magnetic induction, therefore, the silicon and aluminum contents in the chemical compositions of the steel are controlled to be rather low. However, too small contents of silicon and aluminum will give rise to a case in which the crystal grains can not grow normally in the normalization process of the hot-rolled plate. Moreover, the non-oriented silicon steel plate with lower silicon contents tends to generate recrystallization in the course of being hot rolled, which will lead to a case in which there are more fine equiaxed recrystallized grains and less fiber texture rolled in the metallographic texture of the hot rolled plate. Flattening the hot-rolled plate at a lamination compression ratio of 2-5% before it normalizes can increase the stored energy of deformation in order to make the recrystallized texture of the standard plate much thicker. A compression rate by rolling too high in the flattening process will cause the hot-rolled plate to have more internal defects in order to affect grain growth.

The intention of having the normalized and pre-annealed hot-rolled plate is to improve the structure and texture of the grain. An investigation of non-oriented silicon steel indicates that to make a grain structure thick before cold rolling can weaken the texture component. { lll} of the cold-rolled sheet and can intensify the texture component. { okl } of the cold-rolled sheet after it is finished annealed, the texture component. { okl } it is advantageous for the magnetic property. Moreover, the incidental phenomenon that the separated substance becomes thicker may cause the grains to grow even more easily in order to improve magnetic induction and reduce iron loss. In the invention, the normalization temperature of the non-oriented silicon steel plate with high magnetic induction is not below 950 ° C, the thermodifusion period is 30-180S.

The grains of the Gaussian texture (lio) which are advantageous for the magnetic property are usually nucleated and grow in the area deformed by cutting the cold rolled material. If the rate of temperature rise is too low, in the phase of the temperature that is lower, a recovery process will occur in the material, which will reduce the distortion of the reticle, thus, the probability of the Gaussian texture to nuclear will fall greatly. Using a high temperature rise index in the annealing process can quickly cross the temperature range adverse to the evolution of Gaussian texture and can make the texture of the surface. { okl } advantageous for the magnetic property evolve even better, and in this way, can optimize the magnetic induction and the loss of iron. Cooling the annealed sheet slowly can improve its magnetic property. In the invention, the cold rolled sheet is annealed finished by rapidly heating to a temperature between 800 ~ 1000 ° C at a temperature rise rate of = 100 ° C / s and a thermoforming period of 5 ~ 60s, subsequently, it is cooled slowly to 600 ~ 750 ° C at a cooling rate of 3 ~ 15 ° C / s.

Compared to the conventional manufacturing process, the manufacturing process of the invention can raise the magnetic induction of the non-oriented silicon steel by at least 200 Gauss under the precondition of maintaining the same iron loss.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows an interrelation between the compression rate at which the hot rolled plate is cold rolled and the magnetic property of the finished annealed steel.

DETAILED DESCRIPTION OF THE INVENTION The invention is now described in detail by the embodiments and with reference to the accompanying drawings.

Realization 1 (1) The non-oriented hot-rolled silicon steel plate with 2.6 mm thickness, its composition and contents are: Si 0.799%, Al 0.4282%, C 0.0016%, Mn 0.26%, P < 0.022%, S < 0.033%, N < 0.0007%, Nb 0.0004%, V 0.0016%, Ti 0.0009%, the rest is iron and inevitable inclusions. (2) The hot rolled plate is cold rolled with a Compression Index of 1 ~ 10%. (3) The hot-rolled plate is normalized to a normalization homogenization temperature of 970 ° C and maintained at the temperature for 60s, then the normalized plate is pickled, and then, cold rolled in a 0.5 mm steel thickness. (4) The cold-rolled sheet is annealed at a high heating rate of 14? electric annealing oven in a laboratory, with a temperature rise rate of 250 ° C / s, a homogenization temperature of 850 ° C and a thermofusion time of 13s.

It is found that in the case of the hot rolled plate that is cold rolled with a compression ratio of 1 10%, the recrystallized grains of the normalized sheet after being normalized become clearly much thicker, but the microstructure of the product The finished silicon steel remains largely unchanged. In the case of the proportion of a compression ratio of 4 ~ 6%, the magnetic property of the finished silicon steel product comes to be the best with the magnetic induction B50 of up to 1.83T. The magnetic property of the finished annealed silicon steel is shown in Table 1. The interrelation between the compression ratio in which the hot-rolled plate is successively cold-rolled several times in a steel and the magnetic property of the finished annealed steel is shows in Fig. 1.

Table 1 Magnetic property of Silicon Steel not oriented annealing finished The microstructures of both the normalized plate and the finished annealed sheet obtained with different rates or compression ratios by rolling were inspected. It was found that after the hot-rolled plate is slightly cold-rolled, the crystal grains of the normalized plate obviously grew, but the sizes of the glass grains of the annealed-finished sheet do not change clearly. The average grain diameters of both the normalized plate and the annealed-finished sheet are shown in Table 2. There is a good correlation between this result and the magnetic property of the finished sheet product. That is, as the grains of the standard plate become larger, the texture component. { m} of the cold rolled sheet after being annealed finished weakens, while the texture component. { mess} which is advantageous for the magnetic property is intensified, in this way, the magnetic induction B50 of the finished annealed sheet is optimized.

Table 2 Mean grain diameters of both the normalized plate and finished annealed sheet of non-oriented silicon steel.

Realization 2 (1) The non-oriented hot-rolled silicon steel plate with 2.6 mm thickness, its composition and contents are: Si 1%, Al 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 rest is iron and unavoidable inclusions. (2) The hot rolled plate is cold rolled at a rolling compression ratio of 4%. (3) The cold-rolled plate is normalized to a normalization homogenization temperature of 950 ° C and maintained at this temperature for 60s, then the standardized plate is pickled and then cold rolled in a 0.5 mm thick steel . (4) The cold rolled sheet is annealed at a high heating rate in an electric annealing furnace in a laboratory, with different temperature rise rates of 20 ° C / s, 150 ° C / s and 250 ° C / s , respectively, the homogenization temperature of 960 ° C and the thermofusion time of 13s.

The magnetic property of the finished annealed sheet is shown in Table 3.

Table 3 Magnetic property of silicon steel not oriented annealing finished As can be seen in Table 3, the iron loss and magnetic induction of the finished annealed sheet is affected by the rate of temperature rise. As the rate of temperature rise increases, iron loss is reduced and magnetic induction is increased.

Claims

NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and, therefore, what is contained in the following is claimed as property. CLAIMS

1. A non-oriented silicon steel manufacturing process with high magnetic induction comprising the following procedures: 1) Cast and cast a non-oriented silicon steel has the following chemical composition in percent by weight: Si 0.1 ~ 1%, Al 0.005 ~ 1.0%, C = 0.004%, n 0.10 ~ 1.50%, P = 0.2%, S = 0.005%, N < 0.002%, Nb + V + Ti < 0.006%, and the rest is iron and inevitable inclusions; the non-oriented silicon steel is melted and treated with secondary refining in a converter or in an electric furnace, and then cast in a steel ingot; 2) Hot rolling The steel ingot is heated to a temperature between 1150 ~ 1200 ° C, and maintained at the temperature for a certain time; and then hot rolling on a steel plate at a rolling-finished temperature of 830 ~ 900 ° C; when cooled to a higher temperature = 570 ° C, the plate is emboiled; 3) Flattening the hot rolled plate is cold rolled at a compression ratio by rolling of 2 ~ 5%; 4) Normalization after being cold rolled, the hot rolled plate is continuously normalized in a time at a temperature not below 950 ° C, and maintained at the temperature for 30 ~ 180s; 5) Pickling and cold rolling. the standardized plate is pickled, and then cold-rolled several times in a cold-rolled sheet with the thickness of the finished product at a total rolling compression ratio of 70 ~ 80%; 6) Annealing The cold rolled sheet is quickly heated-annealed, where the rate of temperature rise is not below 100 ° C / s, the temperature rises between 800 ~ 1000 ° C and is kept at the temperature for 5 ~ 6Os , subsequently, it is cooled slowly to 600 ~ 750 ° C at a cooling rate of 3 ~ 15 ° C / s.

2. The manufacturing process of non-oriented silicon steel with high magnetic induction as defined in claim 1, characterized in that the annealing atmosphere, in volume percentage, is H2 of 30% ~ 70% + N2 of 70% ~ 30% , and the dew point = -25 ° C. SUMMARY OF THE INVENTION A manufacturing process of non-oriented silicon steel with high magnetic induction comprising the following procedures: 1) melting and casting: the chemical compositions of the steel in percent by weight: Si 0.1 ~ 1%, Al 0.005 ~ 1.0%, C < 0.004%, Mn 0.10 ~ 1.50%, P < 0.2%, S = 0.005%, N < 0.002%, Nb + V + Ti < 0.006%, and the rest is iron; the molten steel is liquefied and subjected to secondary refining and subsequently cast into an ingot; 2) hot rolling: the ingot is heated to 1150 ~ 1200 ° C, and then hot rolled on a plate at a finished-rolling temperature of 830 ~ 900 ° C; at a temperature = 570 ° C, and embobine; 3), flattened: the plate is cold rolled at a compression ratio of 2 ~ 5%; 4) Normalization: the plate is normalized to a temperature not lower than 950 ° C for 30 ~ 180s; 5) pickling and cold rolling: the normalized plate is pickled, and then successively cold rolled several times at a total compression ratio of 70 ~ 80% in a sheet with a finished product thickness; 6) Annealing-finishing: the cold-rolled sheet is rapidly heated to 800 ~ 1000 ° C at a temperature rise rate = at 100 ° C / s and maintained for 5 ~ 60s, then cooled slowly to 600 ~ 750 ° C, and then let it cool naturally. The manufacturing process can raise the magnetic induction of the non-oriented silicon steel by at least 200 Gauss without increasing the iron loss.