CN109097687B - Preparation method of non-oriented silicon steel for direct-drive wind driven generator - Google Patents

Preparation method of non-oriented silicon steel for direct-drive wind driven generator Download PDF

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CN109097687B
CN109097687B CN201811020686.5A CN201811020686A CN109097687B CN 109097687 B CN109097687 B CN 109097687B CN 201811020686 A CN201811020686 A CN 201811020686A CN 109097687 B CN109097687 B CN 109097687B
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CN109097687A (en
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冯大军
石文敏
陈圣林
骆忠汉
胡守天
王晓燕
曹亢
万政武
李珉
杜光梁
杨光
党宁员
张则杰
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Wuhan Iron and Steel Co Ltd
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    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
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    • C—CHEMISTRY; METALLURGY
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
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    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
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    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/12—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties
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    • C21D8/1272—Final recrystallisation annealing
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/34—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of silicon
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    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
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    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
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Abstract

The invention relates to the technical field of non-oriented silicon steel production, in particular to a preparation method of non-oriented silicon steel for a direct-drive wind driven generator. The preparation method of the non-oriented silicon steel for the direct-drive wind driven generator comprises the working procedures of smelting, continuous casting and blank forming, hot rolling, normalizing, acid washing and cold rolling, and alkali washing and continuous annealing, wherein in the smelting working procedure, all components and the range of all components of molten steel of the non-oriented silicon steel are optimized, the iron loss of the non-oriented silicon steel is reduced, and the magnetic performance and the corrosion resistance are improved, namely the low-frequency performance and the corrosion resistance of the non-oriented silicon steel are improved.

Description

Preparation method of non-oriented silicon steel for direct-drive wind driven generator
Technical Field
The invention relates to the technical field of non-oriented silicon steel production, in particular to a preparation method of non-oriented silicon steel for a direct-drive wind driven generator.
Background
At present, a direct-drive wind driven generator generally adopts a permanent magnet synchronous motor structure so as to obtain higher power generation efficiency. However, the non-oriented silicon steel used in the direct-drive wind driven generator at present has the problem of poor low-frequency performance, and can not meet the requirements of the direct-drive wind driven generator. The evaluation parameter of the general low-frequency performance is P1.5/10≤0.60w/kg，B5000≥1.730T。
The application publication number is CN 106487117A's Chinese invention patent application file, it discloses a silicon steel sheet for aerogenerator stator, silicon steel sheet body (1) is formed by welding a plurality of fan-shaped silicon steel sheet units (2) of the same central angle, the inward flange of silicon steel sheet unit (2) is inwards concave and is equipped with a plurality of wire casing (3), the width of silicon steel sheet body (1) is 130 ~ 160mm, and thickness is 0.3mm, and the silicon steel sheet's chemical composition is: 0.04-0.05 wt% of C, 3.20-3.80 wt% of Si, 0.06-0.07 wt% of Mn, 0.010-0.017 wt% of P, 0.004-0.005 wt% of S, 0.08-0.128 wt% of Sn, 0.10-0.15 wt% of Cu, 0.05-0.06 wt% of Al and the balance of Fe. The silicon steel sheet for the stator of the wind driven generator and the rolling method thereof save materials, have low iron loss value, but have no performance index, particularly no low-frequency performance, and do not emphasize corrosion resistance.
If the chinese patent application file that application publication number is CN106435395A again, it discloses a silicon steel sheet for aerogenerator stator, silicon steel sheet body (1) is formed by fan-shaped silicon steel sheet unit (2) welding of a plurality of the same central angle, the inward flange of silicon steel sheet unit (2) is inwards concave and is equipped with a plurality of wire casing (3), the material of silicon steel sheet body (1) is: 0.06-0.08% of C, 2.6-3.2% of Si, 0.15-0.25% of Mn, 0.02-0.03% of Als, 0.2-0.25% of Co, 0.15-0.25% of Cr0.15, 0.05-0.1% of Sn, 0.03-0.05% of V, 0.015-0.025% of Hf, 0.008-0.012% of Ta, 0.002-0.003% of B, 0.004-0.005% of N, 0.02-0.03% of Sc, 0.015-0.025% of Gd, 0.01-0.02% of Yb, less than or equal to 0.05% of P, less than or equal to 0.0025% of S and the balance of Fe. The invention adds noble metals such as Co, Sc, Gd, Yb and the like, is not beneficial to reducing the cost and has no other performance index requirements.
Also, for example, in the chinese patent publication No. CN105886932B, the non-oriented silicon steel for high power factor motor is disclosed, which comprises the following components in wt%: c: less than or equal to 0.0020 percent, Si: 1.70-1.90%, Mn: 0.10-0.20%, P: less than or equal to 0.05 percent, S: less than or equal to 0.0030 percent, Al: 0.25-0.35%, Cr: 0.05-0.50%, N: less than or equal to 0.0020 percent; the production steps are as follows: smelting and forming a blank by adopting a pure steel mode; heating a casting blank; hot rolling; coiling; normalizing; acid washing; cold rolling; annealing the finished product in an N2+ H2 atmosphere; cooling, coating and finishing are carried out according to the conventional method. The thickness of the invention is 0.50mm, the iron loss P1.5/50 is less than or equal to 3.3W/kg, and the B5000 is more than or equal to 1.74T. The patent aims at obtaining higher power factor, and has no low-frequency performance and antirust performance.
Also, for example, in the chinese patent publication No. CN104294185B, the non-oriented electrical steel for high efficiency motors is disclosed, which comprises the following chemical components in percentage by weight: c: less than or equal to 0.0030 percent, Si: 1.9-2.1%, Mn: 0.28 to 0.32%, Al: 0.10-0.60%, P: 0.01-0.06%, S is less than or equal to 0.0050%, Cu: 0.10 to 0.30%, Sb: 0.02-0.05% and less than or equal to 0.0030% of N; the production process comprises the following steps: smelting; cogging; repeatedly forging the blank into a square blank; heating; hot rolling; normalizing; acid washing; cold rolling; and (6) heat treatment. The thickness of the invention is 0.50mm, the iron loss P1.5/50 is less than or equal to 3.3W/kg, and the B5000 is more than or equal to 1.73T. The invention is intended for use in high efficiency motors, and does not emphasize low frequency performance nor the production method for achieving low frequency performance.
For another example, the granted publication number CN103436796B of the invention is chinese patent, which discloses a non-oriented electrical steel for a frequency conversion compressor, comprising the following chemical components in percentage by weight: c: 0.001-0.015%, Si: 2.0 to 2.5%, Al: 0.15 to 0.55%, Mn: 0.15-0.55%, Cr: 0.01-0.039%, Sn is less than or equal to 0.12%, P is less than or equal to 0.08%, S is less than or equal to 0.015%, and N is less than or equal to 0.008%; the production process comprises the following steps: smelting and continuously casting into a blank by adopting a clean steel process; heating the continuous casting blank; rough rolling; fine rolling; coiling; normalizing; acid washing; cold rolling; decarbonizing; soaking; cooling, coating and finishing are carried out according to the conventional method. The invention is to ensure the magnetic property, namely P1.5/50On the premise that B50 is not less than 2.65w/kg and not less than 1.68T, the mechanical property is better, namely the ratio of the elongation to the yield is 0.37-0.43, and the requirements of manufacturing high-speed punching sheets and magnetic properties of the iron core of the inverter compressor are met. The invention considers the frequency conversion and the performance thereof, but has no specific index on the performance under the low-frequency working condition and does not consider the corrosion resistance.
In summary, no preparation method of non-oriented silicon steel with good low-frequency performance and corrosion resistance is reported at present, and marine direct-drive wind driven generators require silicon steel materials with high low-frequency performance and good corrosion resistance, and because marine seawater contains high salt content and is easy to corrode the silicon steel materials in the generators, the non-oriented silicon steel with good low-frequency performance and corrosion resistance is urgently needed to meet the requirements of the marine direct-drive wind driven generators.
Disclosure of Invention
In order to solve the problems, the invention aims to provide a method for preparing non-oriented silicon steel with better low-frequency performance and corrosion resistance for a direct-drive wind driven generator.
In order to achieve the aim, the preparation method of the non-oriented silicon steel for the direct-drive wind driven generator comprises the following continuous annealing processes of smelting, continuous casting blank forming, hot rolling, normalizing, acid pickling and cold rolling and alkali washing, and is characterized in that: in the smelting process, the molten steel of the non-oriented silicon steel contains the following chemical components in percentage by weight: less than or equal to 0.0030 percent, Si: 1.85-2.24%, Mn: 0.15-0.22%, P is less than or equal to 0.030%, S is less than or equal to 0.0030%, Al: 0.25-0.38 percent of Fe, less than or equal to 0.0025 percent of N, less than or equal to 0.12 percent of Cr and/or less than or equal to 0.12 percent of Cu, less than or equal to 0.11 percent of Sn and/or less than or equal to 0.055 percent of Sb, and the balance of Fe and inevitable impurities; simultaneously, the following requirements are met: 2.5-3.0% of Si + Al + Mn + Cr + Cu + Sn + Sb; 0.05-0.16% of Sn + Sb, less than or equal to 0.0055% of S + N, and 10-30% of (Sn + Sb)/(S + N).
Compared with the prior art, the method firstly adjusts the components and the ranges of the components of the molten steel of the non-oriented silicon steel, and the chemical component control of the molten steel mainly refers to the control of main alloy elements such as carbon, silicon, manganese, phosphorus, sulfur and the like and quenching and tempering elements such as chromium, copper, tin, antimony and the like in the steel. The molten steel components and the ranges of the components of the non-oriented silicon steel according to the present invention will be described in detail below.
C, controlling the content of C to be less than or equal to 0.0030% in steel making, so that decarburization in the subsequent annealing process can be avoided, and the magnetic aging of the finished product can be avoided.
Si, which increases the resistance but decreases the saturation flux density (Bs). When Si is < 1.85%, the iron loss increases, but when Si is > 2.24%, the magnetic density decreases. In order to take the magnetic performance of the finished product into consideration, the content of Si should be controlled within the range of 1.85-2.24%.
Mn can control the harmful effect of S, and is beneficial to obtaining coarse MnS. When Mn is less than 0.15%, the improvement of rolling performance is not preferable, but Mn is more than 0.22%, the advantageous effect is not remarkable, and the cost is increased, so that the content of Mn should be controlled to 0.15 to 0.22%.
P is residual element, so the content is controlled to be less than or equal to 0.030 percent.
Al, which can increase the resistance and promote the growth of crystal grains. The general addition amount is 0.25-0.50%, but AlN and an internal oxide layer which are unfavorable for magnetism can be formed by the addition amount, and through a large amount of experimental researches, when Al is less than or equal to 0.03%, the amount of AlN and the internal oxide layer which are formed can be obviously reduced, so that the magnetism is improved, and the cost is also reduced. Therefore, Al is controlled to be less than or equal to 0.03 percent.
One or two of Cr and Cu are added, the effect of Cr and Cu in the invention is to improve the antirust performance, and the total amount is respectively controlled to be less than or equal to 0.12 percent.
Sn and Sb, wherein one or more of Sn and Sb are added, and the Sn and Sb are elements which are easy to be subjected to grain boundary segregation, so that the formation of a (111) plane texture which is unfavorable for magnetism at the grain boundary is favorably inhibited. Less than 0.05% does not achieve the effect of improving texture, while more than 0.16% increases cost and affects surface quality, so the total content of (Sn + Sb) is controlled to be 0.05-0.16%.
S and N, which are elements adverse to magnetism, should be reduced as much as possible, so that (S + N) is controlled to be less than or equal to 0.0055%.
In order to fully exert the effect of increasing the favorable texture of Sn and Sb, the contents of S and N need to be further reduced, so that the (Sn + Sb)/(S + N) is controlled to be 10-30, if the ratio is more than 30, the cost is increased and the adverse effect is generated, and if the ratio is less than 10, the required effect cannot be achieved.
As a preferred scheme, the smelting process is carried out in a pure steel mode, and the specific process is that low-sulfur lime and low-sulfur steel scrap auxiliary materials are added into molten steel to control the sulfur content of the molten steel, wherein the low-sulfur lime accounts for 0.6-1.0 wt% of the molten steel, and the low-sulfur steel scrap accounts for 11-20 wt% of the molten steel; rare earth or calcium is added for treating to further purify the steel, the modification of inclusions in molten steel is promoted, the inclusions float upwards to form slag, the weight percentage of the rare earth in the molten iron is 0.08-0.13%, and then the oxide inclusions MnO and Al are controlled203+Si02MnO content in total weight percent<15％，SiO2Content (wt.)>75％。
The purpose of removing the inclusions is to purify molten steel and further improve the magnetic performance of silicon steel. The floating of the inclusion in the molten steel is carried out in three stages, namely, the formation of the deoxidized inclusion is carried out to a steel slag interface, and finally the deoxidized inclusion enters the molten slag under the action of viscous force and interface tension, so that the aim of removing the deoxidized inclusion is fulfilled. The invention firstly adds low-sulfur lime and low-sulfur scrap steel auxiliary materials into molten steel to control the sulfur content of the molten steel, adds rare earth elements or calcium to treat the molten steel to further purify the steel, promotes the modification of inclusions in the molten steel and floats to form slag, and finally controls oxide inclusions MnO and Al203+Si02MnO and SiO in the total amount2The content of (a) can increase the size of the finished product grains and further reduce the iron loss. Because of the low melting point of MnO, the composite oxide inclusions contain high content of MnO, are in a molten or semi-molten state during hot rolling at a relatively high temperature, and are elongated in the rolling direction, and the growth of crystal grains is hindered during annealing. If only the MnO content is controlled alone, the MnS distribution in the steel becomes unstable and the amount of fine MnS becomes the largest, so thatFurther control of SiO is required2Because MnS is more than SiO2Coarse MnS is formed for core precipitation, the casting blank is not easy to be dissolved in a solid solution when being heated, the number of fine MnS precipitated later is small, the crystal grains of the finished product are coarse, and the iron loss is further reduced.
Preferably, the technological parameters of the hot rolling procedure are that the furnace time is controlled to be 3-4 h, and the tapping temperature is 1140-1180 ℃; and (3) carrying out 7-pass finish rolling after repeating 8-pass rough rolling under high pressure, wherein the finish rolling temperature is controlled to be 840-880 ℃, the coiling temperature is not lower than 720 ℃, and the thickness of the hot-rolled steel coil is 2.0-2.5 mm.
Compared with the prior art, the method optimizes the hot rolling process to further improve the magnetic performance of the non-oriented silicon steel. In the hot rolling step, when the furnace time is less than 3 hours, the slab temperature is not uniform, which affects the rolling stability, and when the furnace time is more than 4 hours, the number of second phase inclusions such as MnS, CuS, AlN and the like is increased, which is detrimental to the magnetic properties, so that the furnace time is controlled to be 3 to 4 hours. The tapping temperature is less than 1140 ℃, the rolling force is increased, so that the plate shape is unqualified, and the tapping temperature is more than 1180 ℃, so that the energy consumption is increased, so that the tapping temperature is required to be 1140-1180 ℃. If the finishing temperature is less than 840 ℃ and is not good for magnetic property, and the finishing temperature is more than 880 ℃, the temperature of the furnace outlet is higher, the energy consumption is increased, and therefore the finishing temperature is required to be 840-880 ℃. If the coiling temperature is high, the grain structure in the hot-rolled coil can be recovered and recrystallized to grow greatly in the subsequent cooling process, which is beneficial to improving the magnetic property, so that the coiling temperature is required to be not lower than 720 ℃.
Preferably, the technological parameters of the normalizing process are that the temperature rising speed is controlled to be 24-30 ℃/s, the normalizing soaking temperature is 915-980 ℃, the heat preservation time is 40-55 s, and the cooling speed is 17-23 ℃/s.
Normalizing is one of the common means for improving the magnetic performance, and if the temperature rise rate is less than 24 ℃/s, more productivity is wasted; and the temperature rise speed is more than 30 ℃/s, the equipment cost is increased, so the temperature rise speed is controlled to be 24-30 ℃/s. If the normalized soaking temperature is less than 915 ℃ and the heat preservation time is less than 40s, the better magnetic performance is not obtained; and the normalizing soaking temperature is 980 ℃ and the heat preservation time is 55s, the existing equipment is required to be modified, and the consumption of spare parts is increased, so that the normalizing soaking temperature is 915-980 ℃ and the heat preservation time is 40-55 s. If the cooling speed is less than 24 ℃/s, more productivity is wasted; and the cooling speed is more than 30 ℃/s, so that the equipment cost is increased, and the cooling speed is controlled to be 17-23 ℃/s.
Preferably, in the pickling and cold rolling step, the thickness of the cold-rolled sheet is 0.50 ± 0.010 mm.
The cold rolling is a key step for realizing high thickness precision, the thickness of a cold rolled plate is controlled to be 0.50 +/-0.010 mm, and the method is used for meeting the requirement of a user on the high precision of a finished product on one hand and avoiding the fluctuation of magnetic performance on the other hand.
Preferably, in the finished product continuous annealing process, the temperature rise speed of finished product annealing is controlled to be 18-22 ℃/s, the soaking temperature is controlled to be 910-955 ℃, the soaking time is 60-75 s, the cooling speed is controlled to be 12-18 ℃/s, and the atmosphere is pure N2(ii) a Then air-cooling and coating a T4 coating with the coating weight of 0.5-1.5 g/m2。
The continuous annealing of the finished product is a key step for realizing the matching of magnetic property and mechanical property, if the temperature rise speed is high<The soaking and heat preservation time can be reduced by 18 ℃/s; and the rate of temperature rise>22 ℃/s, the requirement on equipment is high, and the stable operation is not facilitated, so that the temperature rise speed of finished product annealing is controlled to be 18-22 ℃/s. If the soaking temperature is high<910 ℃ and holding time<60s are not favorable for obtaining the optimal grain structure; and uniform heating temperature>955 ℃ and incubation time>75s, the consumption of spare parts is increased, so the soaking temperature is controlled to be 910-955 ℃, and the soaking time is controlled to be 60-75 s. If the cooling rate is high<12 ℃/s, more production capacity waste can be caused; and the cooling rate>The equipment cost is increased by 18 ℃/s, so that the cooling speed is 12-18 ℃/s. If the amount of coating is<0.5g/m2It is disadvantageous for surface insulation; to the coating amount>1.5g/m2. The weldability and punching property of the steel plate are affected, so the coating weight is controlled to be 0.5-1.5 g/m2。
The invention has the advantages that: compared with the prior art, the method has the advantages that the components of the molten steel of the non-oriented silicon steel and the ranges of the components are adjusted in the smelting process, so that the iron loss of the non-oriented silicon steel is reduced, the magnetic performance is improved, and the corrosion resistance is improved, namely the low-frequency performance and the corrosion resistance of the non-oriented silicon steel are improved. Through the inclusion removing process, the purity of the molten steel is improved, pure molten steel with C, S, N and 0 both less than 20ppm is obtained, and the magnetic performance of the non-oriented silicon steel is further improved. The invention further reduces the influence of the inclusions on the reduction of the magnetic performance and the mechanical property of the non-oriented silicon steel by improving the production process.
Drawings
FIG. 1 is a graph showing the salt spray effect of example 5;
fig. 2 is a graph showing the salt spray effect of comparative example 3.
Detailed Description
For a better understanding of the present invention, reference will now be made in detail to the present invention, which is illustrated in the accompanying drawings.
In order to solve the problem that the existing non-oriented silicon steel has low-frequency magnetic performance which cannot meet the requirements of a direct-drive wind driven generator, the invention provides a preparation method of the non-oriented silicon steel. Specifically, the chemical composition is optimized by adding Sn, Sb, Cr and Cu; the cleanliness of the steel is improved by strictly controlling oxide impurities; the performance regulation and control of the finished product are realized through the parameters of smelting, hot rolling, normalizing, cold rolling and continuous annealing of the finished product; the preferred mode of the method for manufacturing non-oriented silicon steel for direct drive wind power generator according to the present invention will be described in detail with reference to the following specific examples.
Examples 1 to 12
The non-oriented silicon steel of examples 1 to 12 was produced by the following steps:
1) smelting and continuously casting into a blank: the molten steel of the non-oriented silicon steel contains the following chemical components in percentage by weight: less than or equal to 0.0030 percent, Si: 1.85-2.24%, Mn: 0.15-0.22%, P is less than or equal to 0.030%, S is less than or equal to 0.0030%, Al: 0.25-0.38 percent of Fe, less than or equal to 0.0025 percent of N, less than or equal to 0.12 percent of Cr and/or less than or equal to 0.12 percent of Cu, less than or equal to 0.11 percent of Sn and/or less than or equal to 0.055 percent of Sb, and the balance of Fe and inevitable impurities; at the same timeThe method comprises the following steps: 2.5-3.0% of Si + Al + Mn + Cr + Cu + Sn + Sb; 0.05-0.16% of Sn + Sb, less than or equal to 0.0055% of S + N, and 10-30% of (Sn + Sb)/(S + N). The smelting process is smelting according to a pure steel mode, and the specific process is that low-sulfur lime and low-sulfur scrap steel auxiliary materials are added into molten steel to control the sulfur content of the molten steel, wherein the low-sulfur lime accounts for 0.6-1.0 wt% of the molten steel, and the low-sulfur scrap steel accounts for 11-20 wt% of the molten steel; adding rare earth or calcium to purify the steel of the molten steel, promoting the modification of inclusions in the molten steel and floating to form slag, wherein the weight percentage of the rare earth in the molten steel is 0.08-0.13%, and then controlling the oxide inclusions MnO and Al203+Si02MnO content in total weight percent<15％，SiO2Content (wt.)>75％。
2) Hot rolling: controlling the furnace time to be 3-4 h and the discharging temperature to be 1140-1180 ℃. And (3) carrying out 7-pass finish rolling after repeating 8-pass rough rolling under high pressure, wherein the finish rolling temperature is controlled to be 840-880 ℃, the coiling temperature is not lower than 720 ℃, and the thickness of the hot-rolled steel coil is 2.0-2.5 mm.
3) Normalizing: the temperature rising speed is controlled to be 24-30 ℃/s, the normalizing soaking temperature is controlled to be 915-980 ℃, the heat preservation time is controlled to be 40-55 s, and the cooling speed is controlled to be 17-23 ℃/s.
4) Acid pickling and cold rolling: and (3) pickling the normalized plate, and then carrying out 4-pass cold rolling, wherein the thickness of the cold-rolled plate is controlled to be 0.50 +/-0.010 mm.
5) Alkali washing continuous annealing: and (3) continuously annealing the cold-rolled sheet after alkali washing. Because the content of C in the chemical components is less than 30ppm, decarburization annealing is not needed. Controlling the temperature rise speed of finished product annealing to be 18-22 ℃/s, the soaking temperature to be 910-955 ℃, the soaking time to be 60-75 s, the cooling speed to be 12-18 ℃/s, and the atmosphere to be pure N2Then air-cooling and coating a T4 coating layer with the coating weight of 0.5-1.5 g/m2。
The preparation methods of comparative examples I to V are basically the same as the preparation process of the invention, and the differences are that the molten steel of the non-oriented silicon steel has different chemical compositions, different process parameters in the process, and no inclusion removal process is performed on the comparative examples I to V. The detailed steps of comparative examples I-V will not be repeated here.
The molten steel chemical compositions and weight percentages of the non-oriented silicon steels in examples 1-12 and comparative examples I-V are shown in Table 1;
the process parameters in the smelting process of the non-oriented silicon steel preparation method in examples 1-12 and comparative examples I-V are shown in Table 2;
the main process parameters of the non-oriented silicon steel preparation methods in examples 1-12 and comparative examples I-V are listed in Table 3 and Table 4;
the performance detection and effect evaluation of the non-oriented silicon steel obtained in the examples 1-12 and the comparative examples I-V are shown in Table 5;
TABLE 1
Figure BDA0001787237960000081
Figure BDA0001787237960000091
In Table 1, the total alloy is the weight percentage of Si + Al + Mn + Cr + Cu + Sn + Sb, I-V are comparative examples, and the comparative example I: s + N exceeds the range; comparative example ii: sn + Sb is less than 0.05%; comparative example iii: sn + Sb is higher than 0.16%; comparative example iv: the total alloy is less than 2.5%; comparative example v: the total alloy is higher than 3.0%.
TABLE 2
Figure BDA0001787237960000092
Figure BDA0001787237960000101
In Table 4, (MnO + Al)203+Si02) The percentage of MnO content in the total amount is obtained by sampling from the continuous casting slab and analyzing by a chemical electrolysis method.
TABLE 3
Figure BDA0001787237960000102
Figure BDA0001787237960000111
TABLE 4
Figure BDA0001787237960000112
TABLE 5
Figure BDA0001787237960000113
Figure BDA0001787237960000121
In table 5, the salt service test is based on: GB/T10125-: temperature of salt spray box test room: 35 ℃; temperature of the pressure barrel: 47 ℃; NaCl concentration: 5.5 percent; pH value: 6.0.
as can be seen from Table 5 and FIGS. 1 to 2, examples 1 to 12 are excellent not only in rust prevention but also in low-frequency properties, and satisfy the requirement of low-frequency properties (P)1.5/10≤0.60w/kg，B5000Not less than 1.730T) and the rust-proof performance requirement (the rust proportion is less than 70 percent), while the comparative examples I to V can not reach the target requirement. Comparative example i: the rust-proof performance does not reach the standard (the rust proportion is 72 percent)>70% and the low-frequency performance does not reach the standard (P)1.5/10＝0.65>0.60w/kg，B5000＝1.711<1.730T); comparative example ii: the rust-proof performance is not up to the standard (the rust proportion is 75 percent)>70%) and low frequency performance not meeting the standard (P)1.5/10＝0.51<0.60w/kg，B5000＝1.725<1.730T); comparative example iii: the rust-proof performance is not up to the standard (the rust ratio is 81 percent)>70%) and low frequency performance not meeting the standard (P)1.5/10＝0.61>0.60w/kg，B5000＝1.733>1.730T); comparative example iv: the rust-proof performance is not up to the standard (the rust ratio is 72 percent)>70%) and low frequency performance not meeting the standard (P)1.5/10＝0.62>0.60w/kg，B5000＝1.742>1.730T); comparative example v: the rust resistance of the paint does not reach the standard (the rust proportion is 75 percent)>70%) low frequency performance not meeting the standard (P)1.5/10＝0.38<0.60w/kg，B5000＝1.712<1.730T)。
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims (1)

1. A preparation method of non-oriented silicon steel for a direct-drive wind driven generator comprises the working procedures of smelting, continuous casting blank forming, hot rolling, normalizing, acid pickling and cold rolling, and alkali washing and continuous annealing, and is characterized in that: in the smelting process, the molten steel of the non-oriented silicon steel contains the following chemical components in percentage by weight: less than or equal to 0.0030 percent, Si: 1.85-2.24%, Mn: 0.15-0.22%, P is less than or equal to 0.030%, S is less than or equal to 0.0030%, Al: 0.25-0.38%, N is less than or equal to 0.0025%, Cr is less than or equal to 0.12%, and/or Cu is less than or equal to 0.12%, Sn is less than or equal to 0.11%, and/or Sb is less than or equal to 0.055%, and simultaneously: 2.5-3.0% of Si + Al + Mn + Cr + Cu + Sn + Sb; 0.05-0.16% of Sn + Sb, less than or equal to 0.0055% of S + N, 10-30% of (Sn + Sb)/(S + N), and the balance of Fe and inevitable impurities;
the smelting process is smelting according to a pure steel mode, and the specific process is that low-sulfur lime and low-sulfur scrap steel auxiliary materials are added into molten steel to control the sulfur content of the molten steel, wherein the low-sulfur lime accounts for 0.6-1.0 wt% of the molten steel, and the low-sulfur scrap steel accounts for 11-20 wt% of the molten steel; rare earth or calcium is added for treating to further purify the steel, the modification of inclusions in molten steel is promoted, the inclusions float upwards to form slag, the weight percentage of the rare earth in the molten iron is 0.08-0.13%, and then the oxide inclusions MnO and Al are controlled2O3+SiO2MnO content in total weight percent<15％，SiO2Content (wt.)>75％；
The technological parameters of the hot rolling procedure are that the furnace time is controlled to be 3-4 h, and the furnace discharging temperature is 1140-1180 ℃; carrying out 7-pass finish rolling after repeating 8-pass rough rolling under high pressure, controlling the finish rolling temperature to be 840-880 ℃, the coiling temperature to be not lower than 720 ℃, and the thickness of the hot-rolled steel coil to be 2.0-2.5 mm;
the technological parameters of the normalizing process are that the temperature rising speed is controlled to be 24-30 ℃/s, the normalizing soaking temperature is controlled to be 915-980 ℃, the heat preservation time is 40-55 s, and the cooling speed is 17-23 ℃/s;
in the pickling cold rolling process, the thickness of the cold-rolled plate is 0.50 +/-0.010 mm;
in the alkali washing continuous annealing process, the temperature rise speed of finished product annealing is controlled to be 18-22 ℃/s, the soaking temperature is controlled to be 910-955 ℃, the soaking time is 60-75 s, the cooling speed is controlled to be 12-18 ℃/s, and the atmosphere is pure N2(ii) a Then air-cooling and coating a T4 coating with the coating weight of 0.5-1.5 g/m2。
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