CN114086058B - Non-oriented silicon steel with good notch corrosion resistance and production method thereof - Google Patents
Non-oriented silicon steel with good notch corrosion resistance and production method thereof Download PDFInfo
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Abstract
The invention discloses non-oriented silicon steel with good notch corrosion resistance and a production method thereof, belonging to the technical field of electrical steel production. The non-oriented silicon steel comprises the following elements in percentage by mass: si:0.2 to 2.7 percent, mn:0.15 to 1.0 percent, als:0.5 to 1.0 percent, cr:0.1 to 0.3 percent; 0.2 to 0.5 percent of Ni, P: less than or equal to 0.01 percent, and the balance of Fe and unavoidable impurities. The production process comprises the following steps: molten iron pretreatment, converter steelmaking, vacuum treatment, continuous casting, heating, hot rolling, pickling, cold rolling, annealing treatment and insulating layer coating. The invention is produced by reasonable component proportion and matched production process, and finally the non-oriented silicon steel with low iron loss and high magnetic induction and excellent notch corrosion resistance is obtained, thereby effectively meeting the use requirement of the electrical steel.
Description
Technical Field
The invention belongs to the technical field of electrical steel production, and particularly relates to non-oriented silicon steel with good notch corrosion resistance and a production method thereof.
Background
The non-oriented electrical steel is mainly used for manufacturing various rotating motor iron core materials. In addition to excellent electromagnetic properties, it also has good surface quality. In production, in order to ensure that the surface of the obtained non-oriented silicon steel has better quality, an insulating coating is generally coated on the surface of the silicon steel to ensure that the silicon steel has better corrosion resistance, but in use, the steel plate is protected by coating the insulating coating on the surface of the steel plate, but the steel plate substrate has no excellent corrosion resistance, particularly rust is extremely easy to occur at the notch position of the steel plate, so that the use requirement of the steel plate is difficult to meet. Therefore, reducing the notch rust loss in the silicon steel production, transportation and use processes becomes a technical problem to be solved urgently.
Through searching, related patents have been published on improving the surface quality of non-oriented silicon steel to make the surface of the non-oriented silicon steel have corrosion resistance, for example, chinese patent application number is: 201010554155.1, filing date: 11/23/2010, the invention is named: a chromium-free environment-friendly semi-inorganic non-oriented silicon steel insulating coating. The coating for the non-oriented silicon steel disclosed in the application comprises the following chemical components in percentage by mass: polyurethane-acrylic ester-epoxy ethane resin, 5% -25%; 5% -40% of aluminum dihydrogen phosphate; zinc molybdate 5-15%; 1, glue dioxy, 11% -25%; 1 to 5 percent of a nonionic surfactant; the balance of deionized water. This application is more advantageous than conventional phosphate coatings by optimizing the composition of the insulating coating, but is focused on surface corrosion protection and does not relate to the corrosion protection properties of the substrate or end face, thereby making it difficult to address the problem of kerf corrosion resistance.
For another example, chinese patent application No.: 201811077384.1, filing date: the invention is provided with the following creative names: an environment-friendly passivation aluminum-silicon steel plate with excellent corrosion resistance and high temperature resistance and a production method thereof. According to the application, by designing passivation solution components, controlling a roller coating process, film weight control and a drying process, the environment-friendly chromium-free passivation hot-dip aluminized silicon steel plate is produced, a neutral salt spray experiment is carried out until 800 hours, point red rust begins to appear on the plate surface, the plate surface is colorless and changes after heating for 12 hours at 450 ℃, and the plate surface chromatic aberration delta E is less than or equal to 3. The application is also focused on designing an anti-corrosion coating, and corrosion resistance of the steel plate can be improved to a certain extent by controlling a roller coating process, a film weight control process and a drying process, but the anti-corrosion purpose is still achieved by adding an anti-corrosion and temperature-resistant film, and the end face and the substrate are not involved in corrosion prevention.
For another example, chinese patent application No.: 200910273336.4, filing date: 12 months 22 days 2009, the invention is named: cr-containing non-oriented electrical steel and a production method thereof. The application comprises the following chemical components in percentage by weight: c: 0.001-0.015%, mn:0.2 to 0.8 percent, cr:0.1 to 0.8 percent, al:0.1 to 1.4 percent, si: 0.1-0.9%, P <0.08%, S <0.015%, N <0.008%, and the balance Fe and unavoidable impurities; meanwhile, the following requirements are satisfied: the sum of Si+Al is as follows: 0.2 to 2.0 percent. The production method comprises the following steps: refining and continuously casting clean steel into blanks; heating the blank; rough rolling; finish rolling, wherein the accumulated reduction rate c of the previous 4 passes is controlled to be 80-95%; coiling; naturally cooling to room temperature; acid washing; cold 5 rolling; decarburizing; soaking; cooling, coating and finishing are carried out conventionally. In the application, cr is added, so that the main purpose is to improve the yield ratio, solve the inherent contradiction between the magnetic property and the punching performance, and improve the corrosion resistance. Although the non-oriented electrical steel of this application can improve corrosion resistance to some extent, the corrosion resistance is improved only to a limited extent, and it is still difficult to meet the use requirements, especially the notch corrosion resistance, and further improvement is required.
Disclosure of Invention
1. Problems to be solved
The invention aims to overcome the defect that the existing non-oriented silicon steel plate substrate does not have excellent corrosion resistance, particularly rust is very easy to occur at the notch position of the steel plate, so that the use requirement of the steel plate is difficult to meet, and provides non-oriented silicon steel with good notch corrosion resistance and a production method thereof. By adopting the technical scheme of the invention, the problems can be effectively solved, and the non-oriented silicon steel with excellent notch corrosion resistance, low iron loss and high magnetic induction can be obtained, so that the use requirement of the electrical steel is met.
2. Technical proposal
In order to solve the problems, the technical scheme adopted by the invention is as follows:
the non-oriented silicon steel with good notch corrosion resistance comprises the following elements in percentage by mass: si:0.2 to 2.7 percent, mn:0.15 to 1.0 percent, als:0.5 to 1.0 percent, cr:0.1 to 0.3 percent; 0.2 to 0.5 percent of Ni, P: less than or equal to 0.01 percent, and the balance of Fe and unavoidable impurities.
Further, other elements C is less than or equal to 0.0040%, S is less than or equal to 0.0030% Ti is less than or equal to 0.0030%, N is less than or equal to 0.0020%, and the total content of other impurities V, nb, B, ca, mo is controlled below 0.02%.
Further, the sum of the addition amount of the silicon element and the addition amount of the aluminum element is less than 3.5%; the addition amount of the manganese element and the sulfur element satisfies Mn/S not less than 10.
Further, the addition amount of the chromium element and the addition amount of the nickel element satisfy cr+1.56ni=0.40 to 1%.
Further, the addition amount of the chromium element and the nickel element needs to satisfy cr=0.67-1.85 Ni.
The invention relates to a production method of non-oriented silicon steel with good notch corrosion resistance, which comprises the following steps:
(1) Molten iron pretreatment, converter steelmaking and vacuum treatment;
(2) Continuously casting to obtain a casting blank with the thickness of 150-250 mm; the second cooling water of the fan-shaped section adopts a Silicon second cooling process during treatment, so that the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank are controlled within 100 ℃;
(3) Heating a casting blank, hot rolling, pickling, and cold rolling to a thickness of 0.5mm or 0.35mm;
(4) Annealing treatment;
(5) An insulating layer is applied.
Furthermore, when the casting blank is heated, the furnace charging temperature is more than 300 ℃, the heating temperature is controlled to 1050-1200 ℃, and the heating time is controlled to 120-250 min.
Furthermore, when the Si content of the strip steel is below 1.3%, the hot rolled plate with the thickness of 2.6mm, which is obtained by 2-pass rough rolling and 7-frame finish rolling, is directly cold-rolled to the required thickness without normalizing treatment;
when the Si content of the strip steel is within the range of 1.3% -2.5%, carrying out normalizing treatment on a hot rolled plate with the thickness of 2.3-2.6 mm obtained by 2-pass rough rolling and 7-frame finish rolling at 880-950 ℃ to obtain coarse (100) and (110) position grain structures with the thickness of more than 100 mu m;
when the strip steel with Si content above 2.5%, the hot rolled plate with thickness of 1.8-2.3 mm obtained by 2-pass rough rolling and 7-frame finish rolling is normalized at 850-950 ℃, coarse (100) and (110) grain structures with thickness above 130 μm are obtained.
Furthermore, during annealing, nitrogen-hydrogen mixed gas is adopted for protection, the annealing temperature is 800-1000 ℃, and the annealing time is 20-40 s.
Furthermore, during annealing, nitrogen-hydrogen mixture is introduced into the soaking section of the annealing furnace, and H is controlled 2 And N 2 The ratio of (2) is less than 1/3; when the C content is more than 0.0028%, introducing nitrogen-hydrogen mixed wet gas, and controlling the saturation temperature of the wet gas to be 40-80 ℃.
3. Advantageous effects
Compared with the prior art, the invention has the beneficial effects that:
(1) According to the non-oriented silicon steel with good notch corrosion resistance, the components and the mass percentage ranges of the components are optimally designed, so that the obtained non-oriented silicon steel has excellent corrosion resistance on the basis of excellent low iron loss and high magnetic induction performance, particularly the notch corrosion resistance is remarkably improved, and the notch is not easy to rust after the non-oriented silicon steel is stored for a long time, so that the use requirement of the non-oriented silicon steel is met.
(2) According to the non-oriented silicon steel with good notch corrosion resistance, the sum of the addition amounts of silicon and aluminum is controlled within 3.5%, so that the processing performance of the silicon steel can be guaranteed while the magnetic performance of the silicon steel is guaranteed, the processing brittleness of the silicon steel is reduced, the breakage of the silicon steel due to brittle deformation in the cold processing process is prevented, and the production quality of the obtained non-oriented silicon steel is further effectively guaranteed. Meanwhile, the Mn and S elements are precisely controlled, so that the hot rolling plasticity of the silicon steel can be effectively improved, the strength is improved, and the sheet punching property is improved.
(3) According to the non-oriented silicon steel with good notch corrosion resistance, through adding Cr and optimally controlling the adding amount of the Cr, a synergistic effect is easily exerted with other components, particularly with Ni element, and the content relation between Cr and Ni is controlled to meet a specific relational expression, so that the corrosion resistance of a notch can be improved on the basis of ensuring that the obtained non-oriented silicon steel has low iron loss and high magnetic induction, and the use requirement is met.
(4) According to the production method of the non-oriented silicon steel with good notch corrosion resistance, the components, the process steps and the process parameters are optimized, so that the obtained non-oriented silicon steel can be effectively ensured to have excellent notch corrosion resistance, low iron loss and high magnetic induction. Compared with the traditional corrosion-resistant non-oriented silicon steel production, the method has the advantages that the process flow is simple, the aim of corrosion prevention of the matrix is achieved without adding corrosion-resistant and temperature-resistant films, the corrosion resistance of the notch is improved without hot dip galvanizing zinc aluminum magnesium plating, the operation is simple and convenient, and the production cost is low.
(5) According to the production method of the non-oriented Silicon steel with good notch corrosion resistance, through the optimization control of the continuous casting process and the heating temperature and the heating time of the casting blank, particularly during continuous casting, cr and Ni are added into components, the casting blank is treated by adopting a fan-shaped section secondary cooling water and adopting a Silicon secondary cooling process special for Silicon steel, and the maximum temperature and the minimum temperature difference of the surface of the casting blank are controlled within 100 ℃, so that the equiaxial crystal proportion in the casting blank is effectively ensured. Meanwhile, the electromagnetic performance of the obtained non-oriented silicon steel can be effectively ensured by strictly controlling the heating time and the temperature, so that the excellent electromagnetic performance can be maintained on the basis of improving the corrosion resistance of the non-oriented silicon steel, and the use requirement of the electrical steel is met.
Drawings
FIG. 1 is a graph showing the chemical composition of non-oriented silicon steel according to various embodiments and comparative examples of the present invention;
FIG. 2 is a graph showing the results of performance tests of the products obtained in each example of the present invention and each comparative example;
Detailed Description
Under the condition of ensuring excellent electromagnetic performance, the conventional non-oriented silicon steel is relatively thin, and is generally 0.35mm and 0.50mm, so that the corrosion resistance of a substrate and a notch is considered less. However, in practice, because silicon steel is easily rusted and lost at the notch after long-term storage due to the influence of weather in the production, transportation and use processes, the use requirement cannot be met. In order to improve the notch corrosion resistance of the product, the conventional non-oriented silicon steel is generally subjected to hot dip galvanizing of a zinc aluminum magnesium plating layer on the surface of a steel plate, and through pretreatment of plating solution, the solution can fully cover the notch position of the steel plate to form compact hydroxide double-layer compounds, so that the hot dip galvanizing zinc aluminum magnesium plating layer steel plate has excellent notch corrosion resistance. However, the corrosion resistance of the obtained non-oriented silicon steel cannot be fundamentally improved by the mode, and the production flow is prolonged by the treatment of the plating solution, so that the production cost is increased, and the economic benefit of enterprises is not improved.
The invention provides non-oriented silicon steel with good notch corrosion resistance and a production method thereof, and the components, the component proportions and the production process thereof are optimized, so that the notch corrosion resistance of the obtained non-oriented silicon steel can be effectively improved, the electromagnetic performance of the non-oriented silicon steel is ensured, and the use requirements of electrical steel are met. Specifically, the non-oriented silicon steel comprises the following elements in percentage by mass: si:0.2 to 2.7 percent, mn:0.15 to 1.0 percent, als:0.5 to 1.0 percent, cr:0.1 to 0.3 percent; 0.2 to 0.5 percent of Ni, P: less than or equal to 0.01 percent, and the balance of Fe and unavoidable impurities. And other elements C less than or equal to 0.0040%, S less than or equal to 0.0030% Ti less than or equal to 0.0030%, N less than or equal to 0.0020%, and the total content of other impurities V, nb, B, ca, mo is controlled below 0.02%.
In the case of electrical steel, si is the most important alloy element for electrical steel, and to obtain lower iron loss, si content needs to be increased, but as Si content increases, strength of steel also increases, resulting in breakage of steel due to brittle deformation during cold working, which is disadvantageous for working. According to the invention, the iron loss of the obtained non-oriented silicon steel can be reduced and the electromagnetic performance of the non-oriented silicon steel can be improved by strictly controlling the content of Si and adding Al and controlling the content of Si and Al to be not more than 3.5 percent; on the other hand, through the proper Al blending, the lattice distortion of iron can be effectively reduced, the degree of increase of steel brittleness is reduced, and the processing performance is ensured while the magnetic performance of the obtained silicon steel is ensured.
More optimally, cr and Ni are added and the adding proportion is controlled, so that the silicon steel can act cooperatively with other components, and finally the performance of the obtained silicon steel is ensured. The addition of Cr into steel can obviously improve the atmospheric corrosion resistance of the steel, and the improvement of the Cr content is beneficial to refining alpha-FeOOH, and can effectively inhibit the invasion of corrosive anions, in particular Cl-. Meanwhile, the addition of Cr element can prevent the reduction reaction of Fe < 3+ > -Fe < 2+ > during drying in the dry-wet alternating process, so that the corrosion resistance of steel is improved, and the secondary distribution of Cr element in the rust layer is also beneficial to improving the atmospheric corrosion resistance of the steel. In addition, ni is added to enable the self-corrosion potential of bare steel to move forward, so that the stability of a steel matrix is improved. Meanwhile, ni can be enriched in the rust layer, so that the grains of the rust layer are refined and the compactness of the rust layer is improved. Meanwhile, ni can promote the formation of nano-scale and superparamagnetic alpha-FeOOH in the inner rust layer, and block Cl-permeation, so that the rust layer is protective. However, the applicant has found through a great deal of experimental study that, in the non-oriented silicon steel, the addition of Cr with too high a content easily makes the steel hard, is disadvantageous to the punching sheet, and causes serious wear of the die during punching sheet, even breaks the die, and is difficult to process. After the Ni alloy is added, the Ni alloy is similar to Cr, and the Ni alloy and the Cr are combined with O, N to generate nitride and oxide inclusions, so that the hysteresis loss of the steel is increased, the performance is reduced, the magnetic performance is relatively poor, and the use requirement of the electrical steel is difficult to meet. According to the invention, the Cr+1.6Ni is controlled to be 0.40% -1%, so that the electromagnetic performance of the obtained silicon steel is reduced relatively less, but the corrosion resistance of the non-oriented silicon steel notch can be greatly improved after the use requirement of the electrical steel is met. Further, when the addition amount of Cr and Ni satisfies the relation of cr=0.67 to 1.85Ni, the iron loss and the magnetic induction deterioration degree are small.
In addition, according to the silicon steel disclosed by the invention, the Mn/S is more than or equal to 10 by controlling the addition amount of the manganese element and the sulfur element, and Mn and sulfur form MnS, so that the hot embrittlement phenomenon caused by forming FeS with a low melting point along a grain boundary can be prevented, and therefore, a certain amount of Mn is ensured to improve the hot rolling plasticity. Meanwhile, manganese enlarges a gamma phase region, and the solid solubility product of MnS in the gamma phase is lower than that in the alpha phase, so that the MnS can be coarsened, and the grain growth in the future is facilitated. According to the invention, mn/S is controlled in the proportion, so that on one hand, good hot workability and MnS roughening effect can be ensured; on the other hand, the manganese mixed with P partially dissolved in the solution can also improve the hardness of the low-carbon electrical steel, thereby being beneficial to improving the sheet punching property of the obtained silicon steel.
The production method of the unoriented silicon steel comprises the following steps:
(1) 1) pretreating the steel with the chemical components by molten iron, steelmaking by a converter and vacuum treatment;
(2) After vacuum treatment, continuously casting to form a casting blank with the thickness of 150-250 mm; because Cr and Ni are added in steelmaking components, the thermal conductivity coefficient of the material is changed, and in order to ensure higher equiaxed crystal proportion of a casting blank, the fan-shaped section secondary cooling water adopts a Silicon secondary cooling process special for Silicon steel, so that the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank are controlled within 100 ℃.
(3) Heating a casting blank, hot rolling, pickling, and cold rolling to a thickness of 0.5mm or 0.35mm;
the casting blank is heated and hot rolled in a hot charging mode, the charging temperature is more than 300 ℃, the heating temperature of the casting blank is controlled below 1200 ℃, the lower heating temperature is favorable for further reduction of iron loss, but the difficulty of hot rolling control is increased, therefore, the heating time is generally controlled to be 120-250 min above 1050 ℃, the shorter heating time can lead to unfired slab, the surface and the core temperature are uneven, the overlong heating time can lead to dissolution of fine inclusions, the growth of the fine inclusions is realized in the subsequent heat treatment process, grains are pinned, and the electromagnetic performance is affected.
When rolling, when the Si content of the strip steel is below 1.3%, directly cold-rolling the hot-rolled plate with the thickness of 2.6mm, which is obtained by 2-pass rough rolling and 7-frame finish rolling, to the required thickness without normalizing treatment; the strip steel with Si content in the range of 1.3-2.5 percent is subjected to normalizing treatment at 880-950 ℃ to obtain coarse (100) and (110) grain structures with the diameters of more than 100 mu m by 2-pass rough rolling and 7-frame finish rolling to obtain a hot rolled plate with the thickness of 2.3-2.6 mm; the hot rolled plate with the thickness of 1.8-2.3 mm, which is obtained by 2-pass rough rolling and 7-frame finish rolling, is normalized at 850-950 ℃ to obtain coarse (100) and (110) grain structures with the thickness of more than 130 mu m. Cold rolling to the required thickness, typically 0.50mm or 0.35mm.
(4) Annealing treatment and coating an insulating layer;
annealing the cold-rolled strip steel in a nitrogen-hydrogen mixed atmosphere at 800-1000 ℃ and controlling H 2 And N 2 The ratio of (2) is less than 1/3, a required recrystallized structure is obtained, and a certain tension is applied in the annealing process. And then coating an insulating coating on the surface of the strip steel, and drying and curing at the temperature below 500 ℃ to obtain excellent insulating performance.
The invention is further described below in connection with specific embodiments.
Example 1
The non-oriented silicon steel with good notch corrosion resistance in the embodiment has the components with the weight percentage range shown in figure 1. Continuously casting the test steel with the content into a casting blank with the thickness of 230mm after molten iron pretreatment, converter smelting and vacuum treatment, and performing treatment by a Silicon secondary cooling process to control the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank within 100 ℃; heating at 1150 deg.c for 180min, hot rolling into hot rolled coil of 2.6mm thickness, pickling, cold rolling to 0.50mm thickness; then carrying out 810 ℃ for 20s of annealing treatment, introducing 10% H2 and 90% N2 nitrogen-hydrogen mixed gas (if the content of C is more than 0.0028%, introducing nitrogen-hydrogen mixed wet gas, and the saturation temperature of the wet gas is 40-80 ℃, heating the nitrogen-hydrogen mixed gas to be close to the temperature of a humidifying tank through a steam heat exchanger, then entering the humidifying tank, enabling the nitrogen-hydrogen mixed gas to reach required saturation, then heating through the steam heat exchanger again, and then feeding the heated nitrogen-hydrogen mixed gas into a furnace), controlling the tension in the furnace to be 1.8KN, and then drying and solidifying the strip steel coating at 450 ℃ for 15s to obtain a final product.
Example 2
The non-oriented silicon steel with good notch corrosion resistance in the embodiment has the components with the weight percentage range shown in figure 1. Continuously casting the test steel with the content into a casting blank with the thickness of 230mm after molten iron pretreatment, converter smelting and vacuum treatment, and performing treatment by a Silicon secondary cooling process to control the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank within 90 ℃; then heating at 1130 ℃ for 180min, hot-rolling into a hot-rolled coil with the thickness of 2.5mm,after normalized acid washing at 930 ℃, cold rolling to a rolled hard coil with the thickness of 0.50 mm; then at 20% H 2 And 80% N 2 In the mixed gas of (2), the annealing treatment is carried out at 930 ℃ for 35s, the tension in the furnace is controlled to be 1.5KN, and then the insulating coating is coated, dried and cured at 450 ℃ for 15s, so that the final product is obtained.
Example 3
The non-oriented silicon steel with good notch corrosion resistance in the embodiment has the components with the weight percentage range shown in figure 1. Continuously casting the test steel with the content into a casting blank with the thickness of 230mm after molten iron pretreatment, converter smelting and vacuum treatment, and performing treatment by a Silicon secondary cooling process to control the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank within 100 ℃; then heating for 200min at 1100 ℃, hot-rolling into a hot-rolled coil with the thickness of 2.1mm, and cold-rolling into a hard-rolled coil with the thickness of 0.50mm after normalized acid washing at 880 ℃; then at 25% H 2 And 75% N 2 In the mixed gas of (2) and (2) annealing treatment at 960 ℃ for 40s, controlling the tension in the furnace to be 1.4KN, and then, carrying out drying and curing on the coated insulating coating at 450 ℃ for 15s to obtain the final product.
Example 4
The non-oriented silicon steel with good notch corrosion resistance in the embodiment has the components with the weight percentage range shown in figure 1. Continuously casting the test steel with the content into a casting blank with the thickness of 230mm after molten iron pretreatment, converter smelting and vacuum treatment, and performing treatment by a Silicon secondary cooling process to control the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank within 100 ℃; then heating at 1050 ℃ for 250min, hot-rolling into a hot-rolled coil with the thickness of 2.5mm, and cold-rolling into a hard-rolled coil with the thickness of 0.50mm after normalizing and pickling at 850 ℃; then at 25% H 2 And 75% N 2 In the mixed gas of (2) and (2) carrying out annealing treatment at 800 ℃ for 40s, controlling the tension in the furnace to be 1.4KN, and then carrying out drying and curing on the coated insulating coating at 450 ℃ for 15s to obtain the final product.
Example 5
The non-oriented silicon steel with good notch corrosion resistance in the embodiment has the components with the weight percentage range shown in figure 1. The test steel with the content is subjected to continuous casting after molten iron pretreatment, converter smelting and vacuum treatmentCasting blank with the thickness of 230mm is processed by a Silicon secondary cooling process, so that the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank are controlled within 100 ℃; then heating at 1200 ℃ for 120min, hot-rolling into a hot-rolled coil with the thickness of 2.1mm, and cold-rolling into a hard-rolled coil with the thickness of 0.50mm after normalized acid washing at 880 ℃; then at 25% H 2 And 75% N 2 In the mixed gas of (2) 1000 ℃ x 25s, the tension in the furnace is controlled to be 1.4KN, and then the final product is obtained after the insulating coating is coated, dried and cured at 450 ℃ x 15 s.
Comparative example 1
The weight percentage range of the components of the non-oriented silicon steel of the comparative example is shown in figure 1.
Continuously casting the test steel with the component content into a casting blank with the thickness of 230mm after molten iron pretreatment, converter smelting and vacuum treatment, and performing treatment by a Silicon secondary cooling process to control the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank within 100 ℃; then heating at 1150 ℃ for 200min, hot-rolling into a hot-rolled coil with the thickness of 2.6mm, and cold-rolling into a hard-rolled coil with the thickness of 0.50mm through pickling; then at 20% H 2 And 80% N 2 In the mixed gas of (2), the annealing treatment is carried out at 810 ℃ for 20s, the tension in the furnace is controlled at 1.8KN, the surface of the strip steel is coated with insulating paint, and the final product is obtained after drying and curing at 450 ℃ for 15 s.
Comparative example 2
The weight percentage range of the components of the non-oriented silicon steel of the comparative example is shown in figure 1.
Continuously casting the test steel with the component content into a casting blank with the thickness of 230mm after molten iron pretreatment, converter smelting and vacuum treatment, and performing treatment by a Silicon secondary cooling process to control the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank within 100 ℃; then heating at 1130 ℃ for 200min, hot-rolling into a hot-rolled coil with the thickness of 2.5mm, and normal cold-rolling to a hard-rolled coil with the thickness of 0.50mm after normalized acid washing at 930 ℃; then at 20% H 2 And 80% N 2 Annealing treatment is carried out at 930 ℃ for 35s, the tension in the furnace is controlled at 1.8KN, the surface of the strip steel is coated with insulating paint, and the strip steel is dried and cured at 450 ℃ for 15s to obtain the final product.
Comparative example 3
The weight percentage range of the components of the non-oriented silicon steel of the comparative example is shown in figure 1.
Continuously casting the test steel with the component content into a casting blank with the thickness of 230mm after molten iron pretreatment, converter smelting and vacuum treatment, and performing treatment by a Silicon secondary cooling process to control the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank within 100 ℃; then heating at 1100 ℃ for 200min, hot-rolling into a hot-rolled coil with the thickness of 2.1mm, and normal cold-rolling to a hard-rolled coil with the thickness of 0.50mm after normalized acid washing at 880 ℃; then at 20% H 2 And 80% N 2 Respectively carrying out annealing treatment at 960 ℃ multiplied by 40s, controlling the tension in the furnace to be 1.8KN, coating insulating paint on the surface of the strip steel, and drying and curing at 450 ℃ multiplied by 15s to obtain the final product.
Comparative example 4
The weight percentage range of the components of the non-oriented silicon steel of the comparative example is shown in figure 1. The composition is the same as that of the example 1, and the final product is obtained by adopting a conventional non-oriented silicon steel production process, wherein the notch corrosion resistance is improved, but the electromagnetic performance cannot be ensured.
The non-oriented silicon steel products obtained in examples 1 to 5 and comparative examples 1 to 4 were examined for magnetic properties and notch corrosion resistance, and the examination results are shown in FIG. 2. The magnetic properties of the silicon steel obtained in each example were relatively excellent, and although Cr and Ni, which are disadvantageous in terms of magnetic properties, were added to the composition, the electromagnetic properties, particularly the magnetic induction, were substantially equivalent to those of comparative examples 1 to 3 (very little Cr and Ni were added to these three comparative examples). However, the notch corrosion resistance, i.e., the resistance value of the silicon steel in the examples is much higher than that of the silicon steel obtained in the comparative examples, and thus has a good notch corrosion resistance.
Claims (9)
1. The non-oriented silicon steel with good notch corrosion resistance is characterized in that: comprises the following elements in percentage by mass: si:0.2 to 2.7 percent, mn:0.15 to 1.0 percent, als:0.5 to 1.0 percent, cr:0.1 to 0.3 percent; 0.2 to 0.5 percent of Ni, P: less than or equal to 0.01 percent, and the balance of Fe and unavoidable impurities; the addition amount of the chromium element and the addition amount of the nickel element meet the requirement of Cr+1.56Ni=0.40-1%.
2. The non-oriented silicon steel with good notch corrosion resistance as set forth in claim 1, wherein: other elements C less than or equal to 0.0040%, S less than or equal to 0.0030%, ti less than or equal to 0.0030%, N less than or equal to 0.0020%, and the total content of other impurities V, nb, B, ca, mo is controlled below 0.02%.
3. The non-oriented silicon steel with good notch corrosion resistance as set forth in claim 2, wherein: the sum of the addition amount of the silicon element and the addition amount of the aluminum element is less than 3.5%; the addition amount of the manganese element and the sulfur element satisfies Mn/S not less than 10.
4. The non-oriented silicon steel with good notch corrosion resistance according to claim 2, wherein the addition amount of chromium element and nickel element is required to satisfy cr=0.67-1.85 Ni.
5. The method for producing unoriented silicon steel with good notch corrosion resistance according to any one of claims 1 to 4, characterized in that: the method comprises the following steps:
(1) Molten iron pretreatment, converter steelmaking and vacuum treatment;
(2) Continuously casting to obtain a casting blank with the thickness of 150-250 mm; the second cooling water of the fan-shaped section adopts a Silicon second cooling process during treatment, so that the maximum temperature and the minimum temperature difference of the surface temperature of the casting blank are controlled within 100 ℃;
(3) Heating a casting blank, hot rolling, pickling and cold rolling;
(4) Annealing treatment;
(5) An insulating layer is applied.
6. The method for producing non-oriented silicon steel excellent in notch corrosion resistance according to claim 5, wherein: when the casting blank is heated, the furnace feeding temperature is more than 300 ℃, the heating temperature is controlled to 1050-1200 ℃, and the heating time is controlled to 120-250 min.
7. The method for producing non-oriented silicon steel excellent in notch corrosion resistance according to claim 5, wherein:
when the Si content of the strip steel is below 1.3%, the hot rolled plate with the thickness of 2.6mm, which is obtained by 2-pass rough rolling and 7-frame finish rolling, is directly cold-rolled to the required thickness without normalizing treatment;
when the Si content of the strip steel is within the range of 1.3% -2.5%, carrying out normalizing treatment on a hot rolled plate with the thickness of 2.3-2.6 mm obtained by 2-pass rough rolling and 7-frame finish rolling at 880-950 ℃ to obtain coarse (100) and (110) position grain structures with the thickness of more than 100 mu m;
when the strip steel with Si content above 2.5%, the hot rolled plate with thickness of 1.8-2.3 mm obtained by 2-pass rough rolling and 7-frame finish rolling is normalized at 850-950 ℃, coarse (100) and (110) grain structures with thickness above 130 μm are obtained.
8. The method for producing unoriented silicon steel with good notch corrosion resistance according to any one of claims 5 to 7, characterized in that: during annealing, nitrogen-hydrogen mixed gas is adopted for protection, the annealing temperature is 800-1000 ℃, and the annealing time is 20-40 s.
9. The method for producing non-oriented silicon steel with good notch corrosion resistance according to claim 8, wherein: during annealing, introducing nitrogen-hydrogen mixture gas into the annealing furnace soaking section, and controlling H 2 And N 2 The ratio of (2) is less than 1/3; when the C content is more than 0.0028%, introducing nitrogen-hydrogen mixed wet gas, and controlling the saturation temperature of the wet gas to be 40-80 ℃.
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