CN113897556A - Thin-specification medium-low-grade non-oriented silicon steel for improving surface pockmark defects and production method thereof - Google Patents

Thin-specification medium-low-grade non-oriented silicon steel for improving surface pockmark defects and production method thereof Download PDF

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CN113897556A
CN113897556A CN202111200887.5A CN202111200887A CN113897556A CN 113897556 A CN113897556 A CN 113897556A CN 202111200887 A CN202111200887 A CN 202111200887A CN 113897556 A CN113897556 A CN 113897556A
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徐文祥
裴英豪
施立发
程国庆
祁旋
杜军
陆天林
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Maanshan Iron and Steel Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/26—Methods of annealing
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
    • C21D8/1222—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D8/1216—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the working step(s) being of interest
    • C21D8/1233—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D8/1244—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of articles with special electromagnetic properties the heat treatment(s) being of interest
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/04—Making ferrous alloys by melting
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • 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
    • C21D2201/00—Treatment for obtaining particular effects
    • C21D2201/05—Grain orientation

Abstract

The invention provides thin-gauge low-and-low-grade non-oriented silicon steel for improving surface pockmark defects and a production method thereof, wherein the thin-gauge low-and-low-grade non-oriented silicon steel comprises the components of less than or equal to 0.0025 percent of C, less than or equal to 1.65 percent of Si, less than or equal to 1.2 percent of Mn, less than or equal to 0.35 percent of Mn, less than or equal to 0.11 percent of P, less than or equal to 0.2 percent of Als, less than or equal to 0.0025 percent of S, less than or equal to 0.0025 percent of N, less than or equal to 0.0025 percent of Ti, and the balance of Fe and inevitable impurities. Compared with the prior art, the method adopts lower hydrogen concentration, prevents the reduction of iron scale in the furnace, lightens the corrosion degree of the carbon sleeve roller, reduces the nodulation rate of the carbon sleeve roller and improves the surface quality of the strip steel; by adopting reasonable alloy component design, the mechanical strength of the strip steel is improved, the influence degree of the carbon sleeve roller nodules on the surface of the strip steel is reduced, and the surface quality of the strip steel is improved. The thickness of the product is 0.35mm, the incidence rate of the pockmarks on the surface of the roll is reduced, the roll has no hand feeling, and the number of the pockmarks in the period range of the circumference of the roll body is less than or equal to 5.

Description

Thin-specification medium-low-grade non-oriented silicon steel for improving surface pockmark defects and production method thereof
Technical Field
The invention belongs to the technical field of non-oriented electrical steel production, and particularly relates to thin-specification low-medium grade non-oriented silicon steel for improving surface pockmark defects and a production method thereof.
Background
Non-oriented silicon steel, particularly low-grade and medium-grade non-oriented silicon steel with thin specifications, is easily pressed by accretions on the surface of a carbon sleeve roller in the production process of a continuous annealing furnace to generate pockmark defects, so that the surface quality of the silicon steel is poor. Therefore, how to improve the plate surface quality of the low-grade and medium-grade non-oriented silicon steel with thin specification becomes a difficult problem in field production.
CN104878187A published on 9/2/2015 discloses a method for removing accretions, which can effectively suppress the occurrence of reduction reaction by controlling the furnace dew point to be in the range of 25 ℃ to 30 ℃ and adjusting the furnace atmosphere to be an oxidizing atmosphere. However, the scheme describes that the furnace is a wet atmosphere environment, a control method of a dry atmosphere annealing furnace is not mentioned, and a specific concentration range of the reducing atmosphere in the furnace is not clear.
CN102828014B published in 12/19/2012 discloses a method for controlling nodulation of a bottom roller of a carbon sleeve furnace, which controls the use times of a transition roll, performs corresponding thermal compensation on the rotating speed of the furnace roller according to the temperature of strip steel, and adopts high-grade and low-grade alternate production, wherein the time for producing the high grade at each time is not more than 2 days. The invention can obviously prolong the service life of the carbon sleeve roller and improve the quality of the plate surface. However, the scheme does not particularly relate to the production of low-grade non-oriented silicon steel with thin specification, and does not consider the characteristics of low strength and thin thickness of the steel.
Disclosure of Invention
The invention aims to provide thin-specification low-grade and medium-grade non-oriented silicon steel for improving surface pockmark defects and a production method thereof.
The specific technical scheme of the invention is as follows:
the thin-gauge low-medium grade non-oriented silicon steel for improving the surface pockmark defects comprises the following components in percentage by mass:
less than or equal to 0.0025 percent of C, less than or equal to 1.65 percent of Si, less than or equal to 0.35 percent of Mn, less than or equal to 0.06 percent of P, less than or equal to 0.11 percent of Als, less than or equal to 0.2 percent of Als, less than or equal to 0.0025 percent of S, less than or equal to 0.0025 percent of N, less than or equal to 0.0025 percent of Ti, and the balance of Fe and inevitable impurities.
The thin-gauge low-medium grade non-oriented silicon steel for improving the surface pockmark defects has the product thickness of 0.35 mm. The grain size of the finished product structure is 36-40 microns, the yield strength is more than or equal to 285MPa, and the tensile strength is more than or equal to 430 MPa; magnetic induction B50Is not less than 1.736T.
The invention provides a production method of thin-specification low-grade non-oriented silicon steel for improving surface pockmark defects, which comprises the following steps of annealing: the temperature of the heating section is 840 ℃ and 910 ℃, the heating time is 240 ℃ and 500s, and the volume fraction of the hydrogen in the furnace is controlled to be 5-10 percent; the balance of nitrogen; the dew point in the furnace is controlled to be less than or equal to-10 ℃.
And in the annealing step, a rapid heating mode is adopted in a heating section, and the heating rate is 30 ℃/S.
Further, after annealing, coating insulating paint by a coating roller, and curing the insulating paint at 440-570 ℃.
The production method also comprises the step of continuously casting the steel into a plate blank with the thickness of 200-300mm after the steel is subjected to molten iron pretreatment, converter steelmaking and vacuum treatment.
The production method further comprises: the slab is cooled and enters a heating furnace for heating, the temperature of the heating furnace is 1100-1250 ℃, and the heating and heat preservation time is more than or equal to 210 min;
and cooling the plate blank to the temperature of not less than 550 ℃, and heating in a heating furnace.
The production method also comprises the step of hot rolling the heated slab, wherein the final rolling temperature of the hot rolling is 860-900 ℃; rolling into hot rolled plate with thickness of 2.2-2.6 mm;
the production method also comprises the following steps that the temperature of the hot rolled plate blank is reduced to the coiling temperature of 590-660 ℃ after air cooling and water cooling processes;
the production method further comprises the following steps: the normalizing temperature is controlled at 880-;
the production method also comprises pickling after normalization, wherein the pickling temperature is 75-80 ℃.
The production method also comprises cold rolling after pickling, and specifically comprises the following steps: cold rolling on a reversible rolling mill for 6 times, wherein the total rolling reduction rate of the cold rolling is 83-86.5%, and the target thickness is 0.35 mm.
The thin-gauge low-grade non-oriented silicon steel obtained by the process has fewer pockmark defects and excellent plate surface quality.
The applicant finds that the nodulation on the surface of the sleeve roller is caused by that after the iron oxide scale in the annealing furnace is reduced, the iron oxide scale and other dust are accumulated in the surface pores of the carbon sleeve roller, and fusion welding is carried out to form nodulation. It has also been found that excessive hydrogen concentration in the furnace, on the one hand, exacerbates the reduction of scale and the like; on the other hand, the oxidized filler on the surface of the carbon sleeve roller is reduced and corroded, so that pores are exposed, and adhesion positions are provided for nodules. However, when the hydrogen concentration is too low, an oxidizing atmosphere in the furnace is generated, the strip steel is oxidized, an oxide layer is formed in the matrix, and the magnetic performance of the product is deteriorated. The thin low-grade non-oriented silicon steel has low mechanical strength and thin thickness, and is easily pressed by nodules to generate pits and reduce the surface quality.
The electromagnetic property and the mechanical property of the non-oriented silicon steel show a seesaw rule, the thickness of the non-oriented silicon steel produced by the invention is 0.35mm, the thickness is in a low grade, the yield strength reaches 280MPa, and the tensile strength reaches 430 MPa. According to the invention, by adding the P element, the gamma region is reduced, the {100} component is improved, the {111} component is reduced, the iron loss is reduced, and the magnetic induction is improved, so that the better electromagnetic performance is ensured; the P element has a remarkable solid solution strengthening effect, thereby improving the strength of the steel plate.
Compared with the prior art, the method combines the root cause of carbon sleeve roller nodulation and the characteristics of the medium and low grade non-oriented silicon steel to develop and implement corresponding measures. Determining reasonable hydrogen concentration, and finding out a balance point of strip steel oxidation and carbon sleeve roller corrosion; on the other hand, the heat treatment process of the invention enables the grain size of the finished product to be properly refined and improves the mechanical property of the finished product. By adding the P element in a proper proportion, the strength of the finished product is improved, meanwhile, the texture is improved by the P element, and the magnetic property of the product is improved. The final solution of improving the mechanical properties of the finished product and considering the deterioration degree of the magnetic properties is obtained, the influence degree of the nodulation of the carbon sleeve roller on the surface of the strip steel is reduced, and the surface quality of the strip steel is improved. The non-oriented silicon steel produced by the method has the advantages that the thickness of the product is 0.35mm, the occurrence rate of pockmarks on the surface of the product is reduced, the product has no hand feeling, and the number of pockmarks in the circumference period range of the roller body is less than or equal to 5.
Drawings
FIG. 1 is a map of the morphology of a pockmark defect;
FIG. 2 is a metallographic structure of the product of example 1, the average grain size of which is 36 to 40 μm;
FIG. 3 shows the metallographic structure of the final product of comparative example 3, the average grain size of which is 60 to 70 μm.
Detailed Description
The present invention will be described with reference to examples.
The invention provides thin-specification medium-low grade non-oriented silicon steel for improving surface pockmark defects, which comprises the following components in percentage by mass:
less than or equal to 0.0025 percent of C, less than or equal to 1.65 percent of Si, less than or equal to 0.35 percent of Mn, less than or equal to 0.11 percent of P, less than or equal to 0.06 percent of P, and less than or equal to 0.2 percent of Als; s is less than or equal to 0.0025 percent, N is less than or equal to 0.0025 percent, Ti is less than or equal to 0.0025 percent, and the balance is Fe and inevitable impurities.
The thin-gauge low-medium grade non-oriented silicon steel for improving the surface pockmark defects has the product thickness of 0.35 mm.
The production method of the thin-specification low-grade non-oriented silicon steel for improving the surface pockmark defects comprises the following steps:
1) the steel with the chemical components is subjected to molten iron pretreatment, converter steelmaking and vacuum treatment and then is continuously cast into a plate blank with the thickness of 200-300 mm;
2) cooling the plate blank to be not lower than 550 ℃, and then heating the plate blank in a heating furnace, wherein the temperature of the heating furnace is 1100-1250 ℃, and the heating and heat preservation time is not less than 210 min;
3) then hot rolling is carried out, the final rolling temperature of the hot rolling is 860-900 ℃, a hot rolled plate with the thickness of 2.2-2.6mm is rolled, and the temperature is reduced to the coiling temperature of 590-660 ℃ after air cooling and water cooling;
4) the temperature of the acid washing line is controlled to be 880-930 ℃ and the time for normalizing is 2-4 min. The pickling temperature is 75-80 ℃.
5) Cold rolling on a reversible rolling mill for 6 times, wherein the total rolling reduction rate of the cold rolling is 83-86.5%, and the target thickness is 0.35 mm; the temperature of the hot rolled plate blank is reduced to the coiling temperature of 590-660 ℃ after air cooling and water cooling processes.
6) Finally, annealing the finished product, wherein the heating section adopts a rapid heating mode, and the heating rate is 30 ℃/S; the temperature of the heating section is 840 ℃ and 910 ℃, the time is 240 ℃ and 500s, and the volume fraction of the hydrogen in the furnace is controlled to be 5-10%; controlling the dew point in the furnace to be less than or equal to-10 ℃; after annealing, the insulating paint is coated by a coating roller, and the insulating paint is cured at the temperature of 440-570 ℃.
The thin-gauge low-grade non-oriented silicon steel obtained by the process has fewer pockmark defects and excellent plate surface quality.
The specific implementation conditions are as follows:
example 1
A production method of thin-specification low-grade non-oriented silicon steel for improving surface pockmark defects comprises the following steps:
1) and carrying out molten iron pretreatment, converter steelmaking and vacuum treatment, and then continuously casting the mixture into a plate blank with the thickness of 230mm, wherein the plate blank comprises the following chemical components in percentage by weight: 0.0020 percent; si: 1.55 percent; and Als: 0.20 percent; mn: 0.28 percent; p: 0.077%; s: 0.0023%, N: 0.0023%, Ti: 0.0023 percent, and the balance of Fe and inevitable impurity elements.
2) Cooling the plate blank to be not lower than 550 ℃, heating the plate blank in a heating furnace, wherein the temperature of the plate blank in the heating furnace is 1130 ℃, and heating and preserving the temperature for 230 min;
3) hot rolling for 7 times, fine rolling to 2.3mm thickness, final rolling temperature of 870 ℃, and cooling to 650 ℃ after air cooling and water cooling;
4) controlling the normalizing temperature at 930 ℃, normalizing time for 2.5min, and pickling temperature at 75-80 ℃;
5) rolling to 0.35mm by 6 times;
6) heating to 840 ℃ at the speed of 30 ℃/s for annealing for 260s, wherein the volume fraction of hydrogen in the furnace is 8 percent, and the balance is nitrogen; controlling the dew point in the furnace to be less than or equal to-10 ℃; after annealing, the insulating paint is coated by a coating roller, and the insulating paint is cured at the temperature of 440-570 ℃.
The number of the pockmarks in the perimeter period range of the roller body of the finished product of the non-oriented silicon steel manufactured by the process is 4, and no obvious hand feeling exists. Finished steel plate magnetic induction B501.738T, yield strength 286MPa, tensile strength 435 MPa.
Example 2
A production method of thin-specification low-grade non-oriented silicon steel for improving surface pockmark defects comprises the following steps:
1) and carrying out molten iron pretreatment, converter steelmaking and vacuum treatment, and then continuously casting the mixture into a plate blank with the thickness of 230mm, wherein the plate blank comprises the following chemical components in percentage by weight: 0.0021%; si: 1.53 percent; and Als: 0.18 percent; mn: 0.30 percent; p: 0.09%; s: 0.0022%, N: 0.0024%, Ti: 0.0009 percent of Fe and inevitable impurity elements as the rest.
2) Cooling the plate blank to be not lower than 550 ℃, heating the plate blank in a heating furnace at 1180 ℃ for 220 min;
3) hot rolling for 7 times, and finish rolling to 2.3mm thickness, wherein the finish rolling temperature is 880 ℃, and the temperature is reduced to 620 ℃ after air cooling and water cooling;
4) the normalizing temperature is controlled at 910 ℃, the normalizing time is 2.5min, and the pickling temperature is 75-80 ℃.
5) Rolling to 0.35mm by 6 times;
6) heating to 845 ℃ at the speed of 30 ℃/s for annealing, wherein the annealing time is 260s, the volume fraction of hydrogen in the furnace is 9 percent, and the balance is nitrogen; controlling the dew point in the furnace to be less than or equal to-10 ℃; after annealing, the insulating paint is coated by a coating roller, and the insulating paint is cured at the temperature of 440-570 ℃.
The number of the pockmarks in the perimeter period range of the roller body of the finished product of the non-oriented silicon steel manufactured by the process is 5, and no obvious hand feeling exists. Finished steel plate magnetic induction B501.736T, yield strength 287MPa, and tensile strength 432 MPa.
Example 3
A production method of thin-specification low-grade non-oriented silicon steel for improving surface pockmark defects comprises the following steps:
1) the steel is subjected to molten iron pretreatment, converter steelmaking and vacuum treatment and then is continuously cast into a plate blank with the thickness of 230mm, wherein the plate blank comprises the following chemical components in percentage by weight: 0.0019%; si: 1.58 percent; and Als: 0.19 percent; mn: 0.33 percent; p: 0.088%; s: 0.0019 percent, less than or equal to 0.0021 percent of N, less than or equal to 0.0009 percent of Ti, and the balance of Fe and inevitable impurity elements.
2) Cooling the plate blank to be not lower than 550 ℃, heating the plate blank in a heating furnace at 1150 ℃, and keeping the temperature for 220 min;
3) hot rolling for 7 times, and finish rolling to 2.3mm thickness, wherein the finish rolling temperature is 890 ℃, and the temperature is reduced to 600 ℃ after air cooling and water cooling;
4) controlling the normalizing temperature at 920 ℃ and normalizing for 2.5 min; the acid washing temperature is 75-80 DEG C
5) Rolling to 0.35mm by 6 times;
6) heating to 850 ℃ at the speed of 30 ℃/s for annealing, wherein the annealing time is 260s, the volume fraction of hydrogen in the furnace is 6 percent, and the balance is nitrogen; controlling the dew point in the furnace to be less than or equal to-10 ℃; after annealing, the insulating paint is coated by a coating roller, and the insulating paint is cured at the temperature of 440-570 ℃.
The number of the pockmarks in the perimeter period range of the roller body of the finished product of the non-oriented silicon steel manufactured by the process is 3, and no obvious hand feeling exists. Finished steel plate magnetic induction B501.737T, a yield strength of 286MPa and a tensile strength of 435 MPa.
Comparative example 1
A thin-gauge low-and-medium-grade non-oriented silicon steel and a production method thereof specifically comprise the following steps:
1) continuously casting molten steel refined by an RH furnace into a plate blank with the thickness of 230mm, wherein the plate blank comprises the following chemical components in percentage by weight: 0.0020 percent; si: 1.48 percent; and Als: 0.19 percent; mn: 0.30 percent; p: 0.087%; s: 0.0022%, N: 0.0023%, Ti: 0.0010 percent, and the balance of Fe and inevitable impurity elements.
2) The temperature of the plate blank in the heating furnace is 1150 ℃, and the heating and heat preservation time is 220 min;
3) hot rolling for 7 times, and finish rolling to the thickness of 2.3mm, wherein the finish rolling temperature is 890 ℃, and the curling temperature is 600 ℃;
4) controlling the normalizing temperature at 920 ℃, normalizing for 2.5min and pickling at 75-80 ℃; rolling to 0.35mm by 6 times;
5) annealing at 915 ℃, annealing for 260s, wherein the volume fraction of hydrogen in the furnace is 15 percent, and the balance is nitrogen; controlling the dew point in the furnace to be less than or equal to-10 ℃, coating the insulating paint by a coating roller after annealing, and curing the insulating paint at 440-570 ℃.
The number of the pockmarks in the perimeter period range of the roller body of the finished product of the non-oriented silicon steel manufactured by the process is 10, and the surface hand feeling is weaker. Finished steel plate magnetic induction B501.737T, yield strength 280MPa, tensile strength 428 MPa.
Comparative example 2
A thin-gauge low-and-medium-grade non-oriented silicon steel and a production method thereof specifically comprise the following steps:
1) continuously casting molten steel refined by an RH furnace into a plate blank with the thickness of 230mm, wherein the plate blank comprises the following chemical components in percentage by weight: 0.0020 percent; si: 1.51 percent; and Als: 0.19 percent; mn: 0.30 percent; p: 0.008 percent; less than or equal to 0.005 percent of S, less than or equal to 0.005 percent of N, less than or equal to 0.005 percent of Ti, and the balance of Fe and inevitable impurity elements.
2) The temperature of the plate blank in the heating furnace is 1150 ℃, and the heating and heat preservation time is 220 min;
3) hot rolling for 7 times, and finish rolling to the thickness of 2.3mm, wherein the finish rolling temperature is 890 ℃, and the curling temperature is 600 ℃;
4) controlling the normalizing temperature at 920 ℃, normalizing for 2.5min and pickling at 75-80 ℃; rolling to 0.35mm by 6 times;
5) annealing at 915 ℃, annealing for 260s, wherein the volume fraction of hydrogen in the furnace is 7 percent, and the balance is nitrogen; controlling the dew point in the furnace to be less than or equal to-10 ℃, and the balance being nitrogen; after annealing, the insulating paint is coated by a coating roller, and the insulating paint is cured at the temperature of 440-570 ℃.
The number of the pockmarks in the perimeter period range of the roller body of the finished product of the non-oriented silicon steel manufactured by the process is 4, and the surface has obvious hand feeling. Finished steel plate magnetic induction B501.721T, yield strength 220MPa, tensile strength 370 MPa. Comparative example 2 has a low P content, a higher annealing temperature, weakened fine grain strengthening and solid solution strengthening, and reduced strength, so the hand feel is significant.
Comparative example 3
1) Continuously casting molten steel refined by an RH furnace into a plate blank with the thickness of 230mm, wherein the plate blank comprises the following chemical components in percentage by weight: 0.0020 percent; si: 1.51 percent; and Als: 0.19 percent; mn: 0.30 percent; p: 0.008 percent; less than or equal to 0.005 percent of S, less than or equal to 0.005 percent of N, less than or equal to 0.005 percent of Ti, and the balance of Fe and inevitable impurity elements.
2) The temperature of the plate blank in the heating furnace is 1150 ℃, and the heating and heat preservation time is 220 min;
3) hot rolling for 7 times, and finish rolling to the thickness of 2.3mm, wherein the finish rolling temperature is 890 ℃, and the curling temperature is 600 ℃;
4) controlling the normalizing temperature at 920 ℃, normalizing for 2.5min and pickling at 75-80 ℃; rolling to 0.35mm by 6 times;
5) annealing at 915 ℃, annealing for 260s, wherein the volume fraction of hydrogen in the furnace is 15 percent, and the balance is nitrogen; controlling the dew point in the furnace to be less than or equal to-10 ℃, coating the insulating paint by a coating roller after annealing, and curing the insulating paint at 440-570 ℃.
The number of the pockmarks in the perimeter period range of the roller body of the finished product of the non-oriented silicon steel manufactured by the process is 12, and the surface has obvious hand feeling. Finished steel plate magnetic induction B501.719T, yield strength 210MPa, tensile strength 372 MPa.

Claims (10)

1. The thin-specification low-and-medium-grade non-oriented silicon steel for improving the surface pockmark defects is characterized by comprising the following components in percentage by mass:
less than or equal to 0.0025 percent of C, less than or equal to 1.65 percent of Si, less than or equal to 0.35 percent of Mn, less than or equal to 0.06 percent of P, less than or equal to 0.11 percent of Als, less than or equal to 0.2 percent of Als, less than or equal to 0.0025 percent of S, less than or equal to 0.0025 percent of N, less than or equal to 0.0025 percent of Ti, and the balance of Fe and inevitable impurities.
2. The thin gauge low-grade and medium-grade non-oriented silicon steel for improving the surface pockmark defects as claimed in claim 1, wherein the thickness of the thin gauge low-grade and medium-grade non-oriented silicon steel for improving the surface pockmark defects is 0.35 mm.
3. The thin-gauge low-grade non-oriented silicon steel for improving the surface pitting defects of claim 1 or 2, wherein the number of the pitting points in the circumference period range of the roller body of the thin-gauge low-grade non-oriented silicon steel for improving the surface pitting defects is less than or equal to 5.
4. A method for producing a low-gauge, low-grade, non-oriented silicon steel with improved surface pitting defects according to any one of claims 1 to 3, comprising annealing, in particular: the temperature of the heating section is 840 ℃ and 910 ℃, the time is 240 ℃ and 500s, and the volume fraction of the hydrogen in the furnace is controlled to be 5-10%.
5. The production method according to claim 4, characterized in that it comprises: the slab is cooled and then enters a heating furnace for heating, the temperature of the heating furnace is 1100-1250 ℃, and the heating and heat preservation time is more than or equal to 210 min.
6. The production method as claimed in claim 4 or 5, characterized in that the production method comprises hot rolling, the final rolling temperature of which is 860 ℃ and 900 ℃; rolling into hot rolled plate with thickness of 2.2-2.6 mm.
7. The production method according to any one of claims 4 to 6, wherein the production method comprises coiling at a coiling temperature of 590-660 ℃.
8. The production method according to any one of claims 4 to 7, characterized in that it comprises a normalization, in particular: the normalizing temperature is controlled at 880-930 ℃ and the normalizing time is 2-4 min.
9. The production method according to any one of claims 4 to 8, characterized in that the production method comprises pickling at a temperature of 75 to 80 ℃.
10. The production method of any one of claims 4 to 9, wherein the yield strength of the thin-gauge low-medium grade non-oriented silicon steel for improving surface pockmark defects produced by the production method is more than or equal to 285MPa, and the tensile strength is more than or equal to 430 MPa; magnetic induction B50Is not less than 1.736T.
CN202111200887.5A 2021-10-14 2021-10-14 Thin-specification medium-low-grade non-oriented silicon steel for improving surface pockmark defects and production method thereof Pending CN113897556A (en)

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