CN115341083A

CN115341083A - Non-oriented silicon steel for high-frequency motor and production method thereof

Info

Publication number: CN115341083A
Application number: CN202211110009.9A
Authority: CN
Inventors: 岳重祥; 马建超; 吴圣杰; 麻晗
Original assignee: Institute Of Research Of Iron & Steel shagang jiangsu Province; Jiangsu Shagang Group Co Ltd; Zhangjiagang Yangzijiang Cold Rolled Sheet Co Ltd
Current assignee: Institute Of Research Of Iron & Steel shagang jiangsu Province; Jiangsu Shagang Group Co Ltd; Zhangjiagang Yangzijiang Cold Rolled Sheet Co Ltd
Priority date: 2022-09-13
Filing date: 2022-09-13
Publication date: 2022-11-15
Anticipated expiration: 2042-09-13
Also published as: CN115341083B

Abstract

The invention relates to the technical field of non-oriented silicon steel, and particularly provides non-oriented silicon steel for a high-frequency motor and a production method thereof, wherein the production method comprises the following steps: smelting and casting the mixture into a continuous casting billet, heating the continuous casting billet and carrying out hot rolling to obtain a hot rolled plate; the hot rolled plate is normalized to obtain a steel plate with 100 percent of recrystallization and the grain size less than or equal to 80 mu m; after normalization, cold rolling the steel plate to the thickness of less than or equal to 0.30mm after acid washing, and controlling the cold pressing reduction rate at 89-90% to obtain a cold-rolled plate; then annealing the cold-rolled sheet at 820-920 ℃ for 120-150s to obtain the steel sheet with the grain size of the finished product being less than or equal to 100 mu m. The non-oriented silicon steel prepared by the method improves the strength and reduces the high-frequency iron loss P _1.0/1000 And the smelting cost is low, the production process is simple, the production cost is low, and the application requirements of high rotating speed, small volume and high efficiency of the high-frequency motor are met.

Description

Non-oriented silicon steel for high-frequency motor and production method thereof

Technical Field

The invention relates to the technical field of non-oriented silicon steel, in particular to non-oriented silicon steel for a high-frequency motor and a production method thereof.

Background

High frequency motors (or high speed motors) are generally referred to as motors with a rotational speed of more than 10000 r/min. The high-frequency motor has the remarkable advantages of high rotating speed, small relative size, high power density, high efficiency and the like, is widely applied to various occasions such as centrifugal compressors, energy storage flywheels, high-speed grinding machines and the like of air conditioners and refrigerators, and has wide application prospects in electric automobiles and distributed power generation systems. Has become one of the research hotspots in the international electrotechnical field.

The high-frequency motor is mainly characterized by high rotor speed, high stator winding current and high magnetic flux frequency in the iron core. The centrifugal force on the motor rotor is proportional to the square of the linear velocity. Because the rotating speed of the high-frequency motor exceeds 10000r/min, the non-oriented silicon steel for the rotor core is required to have high mechanical strength; meanwhile, the high-frequency motor meets the technical index of high rotating speed, and the volume of the high-frequency motor is far smaller than that of a normal-speed motor with the same power, so that the non-oriented silicon steel for the iron core of the high-frequency motor is required to have higher magnetic induction. In short, to meet the requirements of high-speed, small-volume and high-efficiency control of a high-frequency motor, the non-oriented silicon steel used as the core material of the iron core should have high strength and low high-frequency iron loss P _1.0/1000 And higher magnetic induction.

Most of the existing non-oriented silicon steel production technologies only pay attention to the iron loss under the frequency condition of 50 Hz-400 Hz, only a small amount of production technologies pay attention to the iron loss under the frequency condition of 1000Hz or above, but the production process is complex and is difficult to meet the requirement of rapid development of future high-frequency motors.

For example, chinese patent publication No. CN111471927A discloses a high-magnetic-induction non-oriented silicon steel for an automobile generator and a preparation method thereof, wherein the non-oriented silicon steel comprises the following chemical components in percentage by weight: 0.60 to 1.60 percent of Si, 0.10 to 0.65 percent of Mn, 0.040 to 0.100 percent of P, less than or equal to 0.0080 percent of Als, 0.01 to 0.10 percent of Sn, less than or equal to 100ppm of C, S, O, N and Ti, less than or equal to 25ppm of each element, and the balance of Fe and inevitable impurity elements. Through optimization of components and process design, the magnetic property of the final product is satisfied, and the iron loss P is _1.5/50 Less than or equal to 4.50W/kg, and magnetic induction B ₅₀₀₀ Not less than 1.74T; mechanical propertiesMeets the requirement that the Vickers microhardness HV1 is in the range of 110-120, and the elongation A50 is more than or equal to 40 percent.

Chinese patent publication No. CN 107964631B discloses non-oriented silicon steel with yield strength more than or equal to 500MPa for a high-speed motor rotor, which comprises the following chemical components in percentage by weight: si:4.12 to 4.5%, al:1.62 to 2.0%, mn:0.5 to 2.0 percent, less than or equal to 0.005 percent of N, less than or equal to 0.002 percent of S, less than or equal to 0.003 percent of C, less than or equal to 0.05 percent of P, less than or equal to 0.05 percent of Cu, and less than or equal to 0.01 percent of Ti, nb, V and Zr. The production method comprises the following steps: smelting in a converter; RH vacuum refining; heating a casting blank; finish rolling after rough rolling; coiling; acid washing; cold rolling; and (6) annealing. The yield strength of the non-oriented silicon steel for the high-speed motor rotor is not lower than 500MPa, and the iron loss of a finished product with the thickness of 0.35mm or less is P _1.0/400 ≤18W/kg。

Chinese patent publication No. CN 107974620B discloses a non-oriented silicon steel for a high-speed rotor with yield strength of 600MPa, which comprises the following chemical components in percentage by weight: 0.001 to 0.003 percent of C, 2.6 to 3.4 percent of Si, 0.20 to 0.60 percent of Mn, less than or equal to 0.005 percent of P, less than or equal to 0.005 percent of S, 0.75 to 0.95 percent of Als, 0.002 to 0.006 percent of N and 0.053 to 0.20 percent of Nb. The production steps are as follows: smelting in a converter and casting into a blank; heating the continuous casting billet; conventional rough rolling and finish rolling; normalizing; cold rolling after acid pickling; and (5) continuously annealing. The invention discloses a non-oriented silicon steel with the thickness not more than 0.35mm, the yield strength of a finished product is more than or equal to 600MPa, the tensile strength is more than or equal to 700MPa _1.0/400 ≤35W/kg，B ₅₀₀₀ ≥1.60T。

The non-oriented silicon steel for the ordinary motor provided by the above patents CN111471927A, CN 107964631B and 107974620B can meet the requirements of the high frequency motor in terms of mechanical strength and magnetic induction, but only pay attention to the iron loss under the frequency condition of 50Hz to 400 Hz. The iron loss of the non-oriented silicon steel comprises three parts of hysteresis loss, eddy current loss and abnormal loss. Since the abnormal loss accounts for a relatively small proportion of the core loss, hysteresis loss and eddy current loss are generally focused on. Hysteresis loss P _h ＝k _h *f*B ² Eddy current loss P _e ＝k _e *f ² *B ² . From the formula of hysteresis loss and eddy current loss, hysteresis loss P _h Eddy current loss P proportional to f _e And f ² Is in direct proportion. Therefore, as the frequency increases, the eddy current loss in the iron loss increases greatly. Under the condition of low frequency (50 Hz-400 Hz), the hysteresis loss accounts for most of the iron loss; at high frequencies (greater than or equal to 1000 Hz), the eddy current loss accounts for most of the iron loss. Obviously, due to the difference of the iron loss composition under the high frequency and low frequency conditions, the non-oriented silicon steel with good magnetic performance under the low frequency condition is difficult to ensure that the non-oriented silicon steel still has good magnetic performance under the high frequency, i.e. the non-oriented silicon steel and the production method of the patent are difficult to satisfy the high frequency iron loss P of the non-oriented silicon steel for the high frequency motor _1.0/1000 The use requirement of (2) has the defect of high iron loss at high frequency.

Chinese patent publication No. CN 104480386B discloses 0.2mm thick non-oriented silicon steel for a high-speed motor, which comprises the following components in percentage by weight: 0.001 to 0.025 percent of C, 2.6 to 3.0 percent of Si, 0.25 to 0.55 percent of Al, 0.10 to 0.30 percent of Mn, less than or equal to 0.015 percent of P, 0.001 to 0.0025 percent of S and 0.001 to 0.0025 percent of N. The production steps are as follows: smelting in a vacuum induction furnace and casting into steel ingots; cogging and heating; heating after forging; hot rolling; normalizing; acid washing; carrying out first cold rolling; intermediate annealing; performing secondary cold rolling; annealing the finished product; and measuring the magnetic and mechanical properties according to conventional cooling, shearing, sample preparation and measurement. The invention is to ensure the magnetic property P _1.0/1000 ≤40w/kg，B ₅₀₀₀ On the premise of not less than 1.68T, the yield ratio of mechanical properties is 0.70-0.73, and the use requirement of manufacturing the high-frequency motor iron core is met.

Chinese patent publication No. CN 112538592B discloses a non-oriented silicon steel for high-speed motor with frequency more than or equal to 10000Hz, which comprises the following components by weight percent: less than or equal to 0.003 percent of C, 2.8 to 3.5 percent of Si, 0.05 to 1.0 percent of Mn, less than or equal to 0.0015 percent of P, less than or equal to 0.0008 percent of N, 0.75 to 1.5 percent of Al, less than or equal to 0.0009 percent of S, 0.001 to 0.1 percent of Sb, 0.001 to 0.1 percent of Sn, and the content of Sb and Sn is 0.001 to 0.1 percent; the method comprises the following steps: smelting and casting into a blank; heating and preserving heat of the casting blank, then carrying out hot rolling and coiling; normalizing, preserving heat, pickling and coiling; carrying out first cold rolling; carrying out first continuous annealing; performing second cold rolling; carrying out continuous annealing for the second time; cold rolling for the third time; continuously annealing the finished product; slow cooling, coating an insulating layer and curling. The invention obtains excellent magnetic performance, namely P, under the condition that the thickness is 0.02-0.15 mm _0.1/10000 Not more than 15.5W/kg, P _0.1/400 Not more than 9.5W/kg, B ₅₀₀₀ Not less than 1.6T.

Chinese patent publications CN 104480386B and CN 112538592B disclose non-oriented silicon steel for high-speed motors with current frequencies of 1000Hz and 10000Hz respectively, but the production process is complex and the cost is high. For example, the chinese patent publication No. CN 104480386B discloses a 0.2mm thick non-oriented silicon steel for a high-speed motor, which is produced by secondary cold rolling and secondary annealing; the patent document CN 112538592B discloses non-oriented silicon steel for a high-speed motor with frequency more than or equal to 10000Hz, and the production process comprises three times of cold rolling and three times of annealing.

Therefore, most of the existing non-oriented silicon steel production technologies only pay attention to the iron loss under the frequency condition of 50 Hz-400 Hz, only a small amount of production technologies pay attention to the iron loss under the frequency condition of 1000Hz or above, but the production process is complex and cannot meet the requirement of rapid development of future high-frequency motors.

Disclosure of Invention

The invention aims to overcome the defects of complex production process or high iron loss at high frequency of non-oriented silicon steel for high-frequency motors in the prior art, and provides the non-oriented silicon steel for the high-frequency motors and a production method thereof.

Therefore, the invention provides a preparation method of non-oriented silicon steel for a high-frequency motor, which comprises the following steps:

s1, a step: smelting and casting the mixture into a continuous casting billet, heating the continuous casting billet and carrying out hot rolling to obtain a hot rolled plate, wherein the continuous casting billet comprises the following chemical components in percentage by mass: 2.3 to 3.5 percent of Si, 0.30 to 1.0 percent of Al, 0.2 to 0.5 percent of Mn, less than or equal to 0.0020 percent of C, less than or equal to 0.0020 percent of S, less than or equal to 0.0030 percent of N, less than or equal to 0.01 percent of P, less than or equal to 0.004 percent of Sn + Sb, less than or equal to 0.005 percent of Nb, less than or equal to 0.005 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.005 percent of Mo, less than or equal to 0.05 percent of Cr, less than or equal to 0.05 percent of Ni and less than or equal to 0.05 percent of Cu;

s2, a step: the hot rolled plate is normalized to obtain a steel plate with 100 percent of recrystallization and the grain size less than or equal to 80 mu m;

and S3, a step: after normalization, the steel plate is subjected to acid washing and cold rolling until the thickness is less than or equal to 0.30mm, the cold pressing reduction rate is controlled to be 89-90%, then annealing treatment is carried out, the annealing temperature is 820-920 ℃, and the heat preservation time is 120-150s.

The iron loss of the non-oriented silicon steel comprises three parts of hysteresis loss, eddy current loss and abnormal loss. Hysteresis loss is energy loss caused by hysteresis phenomenon that the magnetic induction lags behind the magnetic field intensity change due to the obstruction of the movement of a domain wall by factors such as impurities, crystal defects, internal stress, crystal orientation and the like in a material and the obstruction of the magnetic flux change in the magnetization and anti-magnetization processes of a magnetic material. The eddy current loss is energy loss caused by eddy current caused by inducing local electromotive force around magnetic flux according to the Faraday's law of electromagnetic induction when the magnetic flux changes in magnitude or direction during the alternating magnetization of a magnetic material. That is, the eddy current loss generated by the rapid change of magnetization when the magnetic wall moves can be calculated according to the classic eddy current loss formula. The abnormal loss is an energy loss caused by a difference in magnetic domain structure when the material is magnetized, and is smaller in iron loss.

It can be seen that the hysteresis loss, the eddy current loss, and the abnormal loss are energy losses generated by the magnetic material during magnetization and demagnetization. Since the abnormal loss accounts for a small proportion of the core loss, hysteresis loss and eddy current loss are generally focused. Hysteresis loss P _h ＝k _h *f*B ² Eddy current loss P _e ＝k _e *f ² *B ² . At low frequencies (50 to 400 Hz), the hysteresis loss is about 70% and the eddy current loss is about 30%. From the formula of hysteresis loss and eddy current loss, P _h Proportional to f, P _e And f ² And is proportional, so the eddy current loss in the iron loss increases greatly as the frequency increases. Under the condition of low frequency (50 Hz-400 Hz), the hysteresis loss accounts for most of the iron loss; at high frequencies (greater than or equal to 1000 Hz), the eddy current loss accounts for most of the iron loss.

Due to the difference of low-frequency and high-frequency iron loss components, the invention adopts a design concept which is completely different from that of the traditional non-oriented silicon steel.

The design concept of the traditional non-oriented silicon steel is as follows: under the condition of low frequency, for non-oriented silicon steel with the same composition, the process design generally requires the design around the finished product large crystal grains because the hysteresis loss accounts for a higher ratio. Because the grain boundary can block the movement of the domain wall, the grain size is increased, the grain boundary is reduced, the hysteresis loss is less, and the iron loss is low. The design of large crystal grains of the finished product is beneficial to reducing the low-frequency iron loss, but the strength of the steel plate is reduced after the crystal grains are increased. That is, under low frequency conditions, low core loss and high strength are contradictory to grain size control. To reduce the iron loss, the grain size should be increased, and then the strength should be increased by other strengthening means such as solid solution strengthening, precipitation strengthening, and dislocation strengthening. Such as: adding alloy elements such as Cu, cr, ni, nb, V, ti and the like in component design; performing incomplete recrystallization annealing or secondary cold rolling on the process design; or a combination of the two.

The design concept of the non-oriented silicon steel of the invention is as follows: under the high-frequency condition, for the same component of non-oriented silicon steel, because the eddy current loss is higher, the finished product crystal grains do not pursue large crystal grains any more during process design, and the eddy current loss is increased because the crystal grains are enlarged, the crystal boundary is reduced, the magnetic domain moving speed is increased, and the magnetization is rapidly changed. That is, under high frequency conditions, the eddy current loss, which accounts for the largest proportion of the high frequency core loss, can be reduced by reducing the crystal grain size, and the entire high frequency core loss is reduced although the hysteresis loss increases. Meanwhile, the strength of the steel plate can be improved by means of grain refinement. Namely, under the high-frequency condition, the low iron loss and the high strength are organically unified for the grain size control, and the fine grain strengthening and the high-frequency low iron loss can be realized simultaneously by controlling the grain size.

The main functions of the elements and the working procedures in the invention are as follows:

c is less than or equal to 0.0020 percent, S is less than or equal to 0.0020 percent, and N is less than or equal to 0.0030 percent: in the non-oriented silicon steel, C, S and N are all harmful elements. The content of C is increased, the iron loss is high, and the magnetic induction is low; high C can also cause magnetic aging problems, with lower levels being better. S and Mn form fine MnS, N and Al form fine AlN, which not only hinders the growth of crystal grains during annealing, but also directly hinders domain wall movement, and hysteresis loss is improved. The non-oriented silicon steel is generally refined in vacuum, the content of C is controlled to be below 0.002%, the content of N is controlled to be below 0.003%, and the difficulty is low. Generally, the content of S in the medium-low grade non-oriented silicon steel is controlled to be below 0.0030 percent, the content of S is continuously reduced, and the cost is increased. However, for the high-grade non-oriented silicon steel for the high-frequency motor, the content of Si is controlled to be 2.3-3.5%, the content of Al is controlled to be 0.30-1.0%, and the content of O in molten steel is greatly reduced. According to the desulfurization reaction CaO + S = CaS + O, the desulfurization difficulty is reduced after the content of O in the molten steel is reduced. Therefore, the invention controls C to be below 0.0020%, S to be below 0.0020%, and N to be below 0.0030%. The control of harmful elements C, S and N not only reduces the hysteresis loss of the non-oriented silicon steel during high-frequency operation, but also improves the magnetic induction and reduces the magnetic aging.

Si 2.3-3.5%, al 0.30-1.0%: si and Al are effective additive elements for improving resistivity, reducing iron loss and improving strength. But the contents of Si and Al are increased, the steel rolling difficulty is increased, edge cracks are easy to occur in the hot rolling process, and strip breakage is easy to occur in the cold rolling process; particularly, when the Si content is more than 3.5%, the rolling difficulty is greatly increased. Meanwhile, the contents of Si and Al are increased, and the magnetic induction of the steel plate is reduced. In the invention, the Si content is controlled to be 2.3-3.5%, the Al content is controlled to be 0.30-1.0%, the high-frequency iron loss is reduced, the strength of the steel plate is improved, and meanwhile, the O content in the molten steel is greatly reduced, thereby creating conditions for ultralow S smelting. The method is characterized in that the method is matched with the control of chemical components (P, sn and Sb), a casting blank is naturally cooled to 350-550 ℃, then is heated to 1080-1100 ℃ at a heating speed of not higher than 10 ℃/min, then is subjected to heat preservation for 0.5-1.0 h and then is subjected to hot rolling, low-temperature normalizing at 820-920 ℃ and measures of preheating a steel plate to 100-200 ℃ before cold rolling, so that the stable production of hot rolling without edge cracks and the stable production of cold rolling under high reduction rate can be realized, and the strip breakage rate of the cold rolling is lower than 0.5%. And the finished product has higher magnetic induction through the low-temperature normalizing process.

0.2-0.5% of Mn: the proper amount of Mn is added, which is beneficial to improving the magnetic property of the steel plate and can improve the strength of the steel plate; mn suppresses hot shortness due to S, and tends to form coarse MnS precipitates with S, thereby reducing the iron loss of the steel sheet. The Mn alloy has higher price, and the Mn content of the invention is controlled to be 0.2-0.5 percent based on the cost consideration. Because the S content is less than or equal to 0.0020 percent and the Mn/S is higher, the method can promote the precipitation and growth of MnS and is beneficial to the magnetic performance.

P is less than or equal to 0.01%: the influence of P on magnetism is small, the strength of the steel plate can be effectively improved by increasing the content of P, but for high-grade non-oriented silicon steel, the cold rolling production difficulty is greatly increased after the content of P is increased, and strip breakage is easy to occur in the rolling process. The control idea of the invention is to adopt high Si and high Al component design and finished product thin specification design, and obtain high strength by finished product fine grain control; the thickness of the finished product is obtained by one-time cold rolling, so that the P is controlled to be less than or equal to 0.01 percent, the rollability of the steel plate is improved, and the production process is simplified.

Sn + Sb ≦ 0.004%: sn and Sb are grain boundary segregation elements, and Sn is added into non-oriented silicon steel independently, sb is added independently or Sn and Sb are added compositely, so that the proportion of {111} unfavorable textures is reduced through segregation of Sn and Sb in grain boundaries, and the magnetic induction of a finished product is improved. Especially in the production flow of an abnormal chemical sequence, the effect is more obvious. However, due to the grain boundary segregation behavior of Sn and Sb, the grain boundary of the steel plate is embrittled, the cold rolling is easy to break, and the production difficulty is increased. Before cold rolling, the hot rolled coil is subjected to normalizing treatment, so that the proportion of the {111} unfavorable texture of a finished product can be obviously reduced, and therefore, sn and Sb are not specially added during component design, and the Sn + Sb content is controlled to be less than or equal to 0.004%, so that the rolling property of the steel plate is ensured, and the production process is simplified.

Nb is less than or equal to 0.005 percent, V is less than or equal to 0.005 percent, ti is less than or equal to 0.005 percent, mo is less than or equal to 0.005 percent, cr is less than or equal to 0.05 percent, ni is less than or equal to 0.05 percent, and Cu is less than or equal to 0.05 percent: nb, V, ti, mo, cr, ni and Cu can reduce the grain size of the finished non-oriented silicon steel product, so that the magnetic performance of the non-oriented silicon steel under the low-frequency condition is reduced, including increased iron loss and reduced magnetic induction intensity; the non-oriented silicon steel for the high-frequency motor requires that a finished product has low iron loss under a high-frequency operation condition, and the eddy current loss is reduced by properly reducing the size of crystal grains. Therefore, the non-oriented silicon steel for the high-frequency motor has appropriate contents of Nb, V, ti, mo, cr, ni and Cu, can reduce the grain size of a finished product of the non-oriented silicon steel, and is beneficial to improving the strength and reducing the high-frequency eddy current loss. However, considering the high alloy price of the elements, the invention is not specially added, only properly relaxes the control requirement and reduces the difficulty of steel making. Nb is controlled to be less than or equal to 0.005 percent, V is controlled to be less than or equal to 0.005 percent, ti is controlled to be less than or equal to 0.005 percent, mo is controlled to be less than or equal to 0.005 percent, cr is controlled to be less than or equal to 0.05 percent, ni is controlled to be less than or equal to 0.05 percent, and Cu is controlled to be less than or equal to 0.05 percent.

Further, in the step S2, the normalizing temperature is 830-930 ℃ and the time is 3-5 min; and/or, obtaining a steel plate with the grain size of 50-80 μm after normalizing.

Further, smelting by adopting a vacuum induction furnace, controlling 0 yarn bundle C + S + N less than or equal to 0.0050%, and casting into a continuous casting billet with the thickness of 220-250 mm.

Further, the casting blank cooling and heating step is that the casting blanks are stacked, naturally cooled to 350-550 ℃, heated to 1080-1100 ℃ at a heating speed of not higher than 10 ℃/min, and then kept for 0.5-1.0 h.

Further, the thickness of the hot rolled sheet obtained in the step S1 is 1.9 to 3.1mm.

Furthermore, the finish rolling temperature is 800-860 ℃, the coiling temperature is 600-660 ℃, the fluctuation range of the finish rolling temperature and the coiling temperature is +/-15 ℃, and the total reduction rate of finish rolling is 92-94%.

Further, after normalizing, cooling the steel plate to 80-150 ℃, and then carrying out ball blasting and acid washing; preferably, hydrochloric acid is adopted for acid cleaning, the temperature of the acid solution is 75-85 ℃, and the concentration of the hydrochloric acid in the acid solution is 120-160 g/L.

Further, the steel sheet is preheated to 100-200 ℃ before cold rolling.

The invention also provides the non-oriented silicon steel for the high-frequency motor, which is prepared by the production method of the non-oriented silicon steel for the high-frequency motor.

Furthermore, the thickness of the finished product of the non-oriented silicon steel for the high-frequency motor is less than or equal to 0.30mm, preferably 0.2-0.3mm, and the grain size of the finished product is less than or equal to 100 mu m, preferably 80-100 mu m.

The technical scheme of the invention has the following advantages:

1. the invention provides a production method of non-oriented silicon steel for a high-frequency motor, which comprises the following steps: s1, a step: smelting and casting the mixture into a continuous casting blank, heating the continuous casting blank and carrying out hot rolling to obtain a hot rolled plate, wherein the continuous casting blank comprises the following chemical components in percentage by mass: 2.3 to 3.5 percent of Si, 0.30 to 1.0 percent of Al, 0.2 to 0.5 percent of Mn, less than or equal to 0.0020 percent of C, less than or equal to 0.0020 percent of S, less than or equal to 0.0030 percent of N, less than or equal to 0.01 percent of P, less than or equal to 0.004 percent of Sn + Sb, less than or equal to 0.005 percent of Nb, less than or equal to 0.005 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.005 percent of Mo, less than or equal to 0.05 percent of Cr, less than or equal to 0 percent of Ni05 percent and Cu is less than or equal to 0.05 percent; and S2, a step: the hot rolled plate is normalized to obtain a steel plate with 100 percent of recrystallization and the grain size less than or equal to 80 mu m; and S3, a step: after normalization, the steel plate is subjected to acid washing and cold rolling until the thickness is less than or equal to 0.30mm, the cold pressing reduction rate is controlled to be 89-90%, then annealing treatment is carried out, the annealing temperature is 820-920 ℃, and the heat preservation time is 120-150s. The steel plate with the finished product thickness of less than or equal to 0.30mm and the finished product grain size of less than or equal to 100 mu m can be obtained by accurately controlling the chemical components and controlling the recrystallization percentage, the grain size, the steel plate thickness, the rolling reduction, the annealing temperature and the annealing time in the steps, the strength is improved, and the high-frequency iron loss P is reduced _1.0/1000 The smelting cost is low, the production process is simple, the production cost is low, the application requirements of high rotating speed, small volume and high efficiency of the high-frequency motor are met, alloy strengthening elements such as Cu, cr, ni, nb, V and Ti are not required to be additionally added, and texture control elements such as Sn and Sb are not required to be added.

Wherein the hot rolled plate obtains 100% recrystallization through normalizing, and the steel plate with the grain size less than or equal to 80 mu m, especially the steel plate with the grain size of 50-80 mu m, is beneficial to cold rolling and creates conditions for controlling the grain size in the annealing process. Therefore, the cold pressing reduction rate is controlled to be 89% -90%, the storage energy and nucleation points are improved, the annealing nucleation rate is increased, and conditions are created for accurately and stably controlling the grain size of the finished product in the annealing process. The annealing at 820-920 ℃ for 120-150s is combined, the control of the conditions of the three procedures is combined with the precise control of chemical components to ensure that the complete recrystallization is realized, and the grain size of the finished product is controlled to be less than or equal to 100 mu m. Cold rolling to the thickness of less than or equal to 0.30mm, improving the resistivity of the steel plate through thickness reduction, and reducing high-frequency iron loss; the grain size of the finished product is less than or equal to 100 mu m, the eddy current loss under the high-frequency condition is reduced by controlling the grain size of the finished product, the high-frequency iron loss is reduced, and the strength of the steel plate is improved by means of fine grain reinforcement.

2. According to the production method of the non-oriented silicon steel for the high-frequency motor, the chemical components are accurately controlled and combined with the normalizing of keeping the temperature at 830-930 ℃ for 3-5min, and the heating is carried out at a low temperature for a long time, so that the complete recrystallization of a hot rolled plate is realized, and the excessive crystal grains are avoided, so that the size of the crystal grains is less than or equal to 80 mu m.

3. The invention provides a production method of non-oriented silicon steel for a high-speed motor, which comprises the steps of stacking casting blanks, naturally cooling the casting blanks to 350-550 ℃, heating the casting blanks to 1080-1100 ℃ at a heating speed of not higher than 10 ℃/min, and then preserving heat for 0.5-1.0 h, wherein in the process of cooling and heating the casting blanks, the casting blanks are prevented from being cooled and heated quickly by controlling the natural cooling and heating speed, the heating temperature and the heat preservation time, so that the high-silicon steel casting blanks are prevented from cracking to influence the subsequent steel rolling; meanwhile, the stacking of the casting blanks is also beneficial to the growth of precipitates. In order to prevent MnS and other precipitates in the steel from being dissolved in the heating process, the non-oriented silicon steel is subjected to furnace entering with the temperature and low-temperature short-time heating in the hot rolling process by controlling the conditions.

4. According to the production method of the non-oriented silicon steel for the high-speed motor, the thickness of the hot rolled plate obtained in the step S1 is controlled to be 1.9-3.1 mm, and the method is beneficial to subsequent cold rolling at a high reduction ratio. The finish rolling temperature is controlled to be 800-860 ℃, the coiling temperature is controlled to be 600-660 ℃, the fluctuation range of the finish rolling temperature and the coiling temperature is +/-15 ℃, and the total reduction rate of finish rolling is 92-94%, so that the subsequent normalizing and annealing process is facilitated to control the grain size more accurately and stably.

5. According to the production method of the non-oriented silicon steel for the high-speed motor, provided by the invention, after normalization, the steel plate is cooled to 80-150 ℃, then shot blasting is carried out, and then acid pickling is carried out, so that the bad plate shape caused by rapid cooling is avoided, and the temperature drop of acid liquor in the acid pickling process is reduced.

6. According to the production method of the non-oriented silicon steel for the high-speed motor, the steel plate is preheated to 100-200 ℃ before cold rolling, so that the rolling property of the steel plate can be further improved, and better conditions are created for stable cold rolling at a high reduction ratio.

7. The non-oriented silicon steel for the high-speed motor provided by the invention is subjected to one-time cold rolling to obtain a finished product with the thickness of 0.2-0.3mm, and the high-frequency iron loss is further reduced by reducing the thickness of the finished product and improving the resistivity of a steel plate.

Detailed Description

The following examples are provided to better understand the present invention, not to limit the best mode, and not to limit the content and protection scope of the present invention, and any product that is the same or similar to the present invention and is obtained by combining the present invention with other features of the prior art and the present invention falls within the protection scope of the present invention.

The examples do not show the specific experimental steps or conditions, and can be performed according to the conventional experimental steps described in the literature in the field. The reagents or instruments used are not indicated by manufacturers, and are all conventional reagent products which can be obtained commercially.

Examples 1 to 11 each provide non-oriented silicon steel for a high-frequency motor, the chemical components of which are, by mass, shown in table 1, and the balance being Fe and unavoidable impurities; the non-oriented silicon steels for high-frequency motors prepared in the examples were steel sheets having thicknesses shown in table 1.

TABLE 1

The non-oriented silicon steel for the high-frequency motor in the embodiments of the invention is produced according to the following steps:

(1) Smelting by using a vacuum induction furnace, and casting into a continuous casting billet with the thickness of 220 mm; the chemical compositions of the continuous casting slabs are shown in table 1; nb, V, ti, mo, cr, ni and Cu are not specially added in the smelting process, but the control requirements are properly relaxed, and the steel-making difficulty is reduced by controlling Nb to be less than or equal to 0.005 percent, V to be less than or equal to 0.005 percent, ti to be less than or equal to 0.005 percent, mo to be less than or equal to 0.005 percent, cr to be less than or equal to 0.05 percent, ni to be less than or equal to 0.05 percent and Cu to be less than or equal to 0.05 percent.

(2) Stacking the continuous casting billets obtained in the step (1), naturally cooling the continuous casting billets to 450 ℃, sending the continuous casting billets into a heating furnace, heating the continuous casting billets at a heating speed of 5 ℃/min, and then preserving heat, wherein the heating temperature and the heat preservation time are shown in table 2.

(3) Carrying out rough rolling and finish rolling on the continuous casting billet heated in the step (2), wherein the rough rolling adopts a 1+5 mode, and an intermediate billet is obtained through six-pass rolling; then, 7 passes of finish rolling and coiling are carried out to obtain a hot rolled coil. The thickness of the intermediate slab obtained by rough rolling, the finish rolling temperature, the total reduction ratio in the finish rolling process, the thickness of the obtained hot rolled plate, and the coiling temperature are shown in Table 2.

(4) Putting the hot rolled coil obtained in the step (3) in pure dry N ₂ Normalizing in the atmosphere, wherein the normalizing temperature and the normalizing time are shown in Table 3; after the steel plate is cooled to 100 ℃ after normalization, shot blasting is carried out firstly, and then hydrochloric acid is adopted for acid cleaning, wherein the temperature of the acid liquid is 80 ℃, the concentration of the hydrochloric acid in the acid liquid is 140g/L, and Fe in the acid liquid ²⁺ The mass concentration of (A) is controlled to be 50 +/-20 g/L. Metallographic structure detection was performed on the normalized steel plates of the respective examples, and the volume ratio of the recrystallized structure and the recrystallized grain size obtained by measurement are shown in table 3;

(5) And (5) preheating the normalized and pickled steel plate obtained in the step (4), and then carrying out cold rolling, wherein the preheating temperature, the pre-rolling thickness, the post-rolling thickness and the cold rolling reduction are respectively shown in table 4.

(6) H, putting the rolled hard steel plate obtained in the step (5) in a container ₂ And N ₂ Continuous annealing in a mixed atmosphere, H ₂ The content is 15 percent; the annealing temperature and holding time are shown in Table 4.

(7) And (4) coating and finishing the steel plate obtained in the step (6) according to a conventional method.

TABLE 2

TABLE 3

TABLE 4

Comparative example

Comparative examples 1 to 3 each provide non-oriented silicon steel whose chemical components are shown in table 5 in mass percent; the non-oriented silicon steels prepared in each proportion are steel plates with the thicknesses shown in table 5.

TABLE 5

The non-oriented silicon steels of comparative examples 1 to 3 were produced according to the low-frequency non-oriented silicon steel design idea:

the production steps of the non-oriented silicon steel of comparative examples 1 to 3 were as follows:

(1) Smelting by using a vacuum induction furnace, and casting into a continuous casting billet with the thickness of 220 mm; the chemical composition of the slab is shown in Table 5.

(2) Stacking the continuous casting billets obtained in the step (1), naturally cooling the continuous casting billets to 450 ℃, sending the continuous casting billets into a heating furnace, heating the continuous casting billets at a heating speed of 5 ℃/min, and then preserving heat, wherein the heating temperature and the heat preservation time are shown in table 6.

(3) Carrying out rough rolling and finish rolling on the continuous casting blank heated in the step (2), wherein the rough rolling adopts a 1+5 mode, and an intermediate blank is obtained through six-pass rolling; then, 7 passes of finish rolling and coiling are carried out to obtain a hot rolled coil. The thickness of the intermediate slab obtained by rough rolling, the finish rolling temperature, the total reduction ratio in the finish rolling, the thickness of the hot rolled sheet obtained, and the coiling temperature are shown in Table 6.

(4) Putting the hot rolled coil obtained in the step (3) in pure dry N ₂ Normalizing in the atmosphere, wherein the normalizing temperature and the normalizing time are shown in Table 7; after the steel plate is cooled to 100 ℃ after normalization, shot blasting is carried out firstly, and then hydrochloric acid is adopted for acid cleaning, wherein the temperature of the acid liquid is 80 ℃, the concentration of the hydrochloric acid in the acid liquid is 140g/L, and Fe in the acid liquid ²⁺ The mass concentration of (A) is controlled to be 50 +/-20 g/L. Metallographic structure detection was performed on the normalized steel sheets of the respective comparative examples, and the measured recrystallized structure volume ratio and recrystallized grain size were respectively shown in table 7;

(5) And (5) preheating the normalized pickled steel plate obtained in the step (4), and then carrying out cold rolling, wherein the preheating temperature, the pre-rolling thickness, the post-rolling thickness and the cold rolling reduction are shown in a table 8 respectively.

(6) H, placing the rolled hard steel plate obtained in the step (5) in a furnace ₂ And N ₂ Continuous annealing in a mixed atmosphere, H ₂ The content is 15 percent; the annealing temperature and the holding time are shown in Table 8.

TABLE 6

TABLE 7

	Normalizing temperature (. Degree.C.)	Normalizing time(s)	Recrystallized structure volume ratio (%)	Recrystallized grain size (. Mu.m)
					Comparative example 1	938	215	100	123
Comparative example 2	955	215	100	114
					Comparative example 3	978	215	100	116

TABLE 8

The non-oriented silicon steels obtained in examples 1 to 11 and comparative examples 1 to 3 were tested for recrystallized grain size and recrystallized structure volume ratio (%), yield strength and tensile strength, and iron loss P _1.0/1000 The non-oriented silicon steels obtained in examples 1 to 11 were tested for magnetic induction B ₅₀₀₀ . The results are shown in the following table.

TABLE 9

As can be seen from the above examples 1 to 11, the non-oriented silicon steel for high frequency motors according to the embodiments of the present invention has high strength and high magnetic induction, and has a high frequency iron loss P _1.0/1000 The method has the advantages of low smelting cost, simple production process and low production cost, and meets the application requirements of high-frequency motors.

Comparative examples 1-3 the same steelmaking process and composition as in examples 9, 10, and 11, respectively, was used to increase the normality by high temperature normalizationAnd (4) changing the grain size of the plate, and combining small reduction rate cold rolling and high-temperature annealing to obtain a finished product large grain. The results show that comparative examples 1, 2, 3 have a significant increase in grain size, but low strength, high frequency core loss P, compared to corresponding examples 9, 10, 11 _1.0/1000 The increase is significant.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications derived therefrom are intended to be within the scope of the invention.

Claims

1. A production method of non-oriented silicon steel for a high-frequency motor is characterized by comprising the following steps:

s1, a step: smelting and casting the mixture into a continuous casting billet, heating the continuous casting billet and carrying out hot rolling to obtain a hot rolled plate, wherein the continuous casting billet comprises the following chemical components in percentage by mass: 2.3 to 3.5 percent of Si, 0.30 to 1.0 percent of Al, 0.2 to 0.5 percent of Mn0, less than or equal to 0.0020 percent of C, less than or equal to 0.0020 percent of S, less than or equal to 0.0030 percent of N, less than or equal to 0.01 percent of P, less than or equal to 0.004 percent of Sn and Sb, less than or equal to 0.005 percent of Nb, less than or equal to 0.005 percent of V, less than or equal to 0.005 percent of Ti, less than or equal to 0.005 percent of Mo, less than or equal to 0.05 percent of Cr, less than or equal to 0.05 percent of Ni and less than or equal to 0.05 percent of Cu;

and S2, a step: the hot rolled plate is normalized to obtain a steel plate with 100 percent of recrystallization and the grain size less than or equal to 80 mu m;

2. The method for producing non-oriented silicon steel for high-frequency motors according to claim 1, wherein in the step S2, the normalizing temperature is 830 to 930 ℃ and the time is 3 to 5min; and/or obtaining a steel plate with the grain size of 50-80 mu m after normalizing.

3. The production method of non-oriented silicon steel for the high-frequency motor as claimed in claim 1 or 2, characterized in that smelting is performed by using a vacuum induction furnace, controlling 0< C + S + N ≦ 0.0050%, and casting into a continuous casting slab with a thickness of 220-250 mm.

4. The method for producing non-oriented silicon steel for high-frequency motors according to any one of claims 1 to 3, wherein the step of cooling and heating the cast slab comprises stacking the cast slabs, naturally cooling the stacked slabs to 350 to 550 ℃, heating the slabs to 1080 to 1100 ℃ at a heating rate of not more than 10 ℃/min, and then keeping the temperature for 0.5 to 1.0 hour.

5. The method for producing non-oriented silicon steel for high frequency motors as claimed in any one of claims 1 to 4, wherein the thickness of the hot rolled sheet obtained in the step S1 is 1.9 to 3.1mm.

6. The method for producing non-oriented silicon steel for a high-frequency motor according to any one of claims 1 to 5, wherein the finish rolling temperature is 800 to 860 ℃, the coiling temperature is 600 to 660 ℃, the fluctuation range of the finish rolling temperature and the coiling temperature is ± 15 ℃, and the total reduction rate of finish rolling is 92 to 94%.

7. The method for producing the non-oriented silicon steel for the high-frequency motor according to any one of claims 4 to 6, wherein the steel sheet is cooled to 80 to 150 ℃ after being normalized, and then is subjected to shot blasting and then acid pickling.

8. The method for producing non-oriented silicon steel for high frequency motors according to any one of claims 1 to 7, characterized in that the steel sheet is preheated to 100 to 200 ℃ before cold rolling.

9. Non-oriented silicon steel for high-frequency motors, obtained by the production method of non-oriented silicon steel for high-frequency motors as claimed in any one of claims 1 to 8.

10. The non-oriented silicon steel for high frequency motors as claimed in claim 9, wherein the finished thickness of the non-oriented silicon steel for high frequency motors is 0.30mm or less, preferably 0.2-0.3mm, and the finished grain size is 100 μm or less, preferably 80-100 μm.