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CN-122013057-A - High-strength low-coercivity electromagnetic pure iron cold-rolled sheet strip steel and manufacturing method thereof

CN122013057ACN 122013057 ACN122013057 ACN 122013057ACN-122013057-A

Abstract

The invention discloses high-strength low-coercivity electromagnetic pure iron cold-rolled sheet strip steel and a manufacturing method thereof, wherein the high-strength low-coercivity electromagnetic pure iron cold-rolled sheet strip steel contains Fe and unavoidable impurities, and further contains the following chemical elements, by mass, less than or equal to 0.003% of C, less than or equal to 0.05-0.25% of Mn, 0.04-0.10% of P, less than or equal to 0.003% of Al, 0.005-0.016% of O, less than or equal to 0.02% of Cu, less than or equal to 0.03% of Cr and less than or equal to 0.02% of Ni. The invention also discloses a manufacturing method of the high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel, which comprises the steps of smelting and casting, hot rolling, pickling and cold rolling, continuous annealing, annealing soaking temperature of 630-670 ℃, soaking heat preservation time of 70-150 s and flattening. Said invented high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel possesses good yield strength, tensile strength, surface hardness and good extensibility, at the same time it also possesses proper coercivity.

Inventors

  • HUANG JUNJIE
  • YAN YUANYUAN
  • DAI JINGGE
  • HE YUTIAN
  • TIAN ZHONGQING
  • ZHANG WENQI

Assignees

  • 宝山钢铁股份有限公司
  • 宝钢湛江钢铁有限公司

Dates

Publication Date
20260512
Application Date
20241111

Claims (13)

  1. 1. The high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel comprises Fe and unavoidable impurities, and is characterized by further comprising the following chemical elements in percentage by mass: C≤0.003%; Mn:0.05~0.25%; P:0.04~0.10%; 0<Al≤0.003%; O:0.005~0.016%; Cu≤0.02%; Cr≤0.03%; Ni≤0.02%。
  2. 2. The high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel according to claim 1, which is characterized by comprising the following chemical elements in percentage by mass: C≤0.003%; Mn:0.05~0.25%; P:0.04~0.10%; 0<Al≤0.003%; O:0.005~0.016%; Cu≤0.02%; Cr≤0.03%; Ni≤0.02%; The balance being Fe and unavoidable impurities.
  3. 3. The high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel according to claim 1 or 2, wherein the mass percentage of each chemical element is 2 XC+N+Al less than or equal to 0.009%.
  4. 4. The high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel according to claim 1 or 2, in which the content of each impurity element satisfies at least one of S≤0.007%, si≤0.01%, N≤0.003% and Ti≤0.005% in unavoidable impurities.
  5. 5. The high-strength low-coercive force electromagnetic pure iron cold-rolled sheet steel according to claim 1 or 2 wherein 80% -90% of the matrix structure is recrystallized equiaxed ferrite and the grain diameter size of the equiaxed ferrite ranges from 10 μm to 100 μm.
  6. 6. The high strength low coercivity electromagnetic pure iron cold rolled sheet steel of claim 5, where after magnetizing annealed, 85% -95% of equiaxed ferrite has a grain size in the range of 100-400 μm.
  7. 7. The high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel according to claim 1 or 2, characterized in that the yield strength is not less than 220MPa, the tensile strength is not less than 300MPa, the elongation is not less than 40% and the surface hardness HV5 is not less than 100.
  8. 8. The high-strength low-coercivity electromagnetic pure iron cold-rolled sheet strip steel according to claim 1 or 2, which is characterized in that the coercivity after magnetization annealing is less than or equal to 32A/m.
  9. 9. The high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel according to claim 1 or 2, which is characterized in that the thickness is 0.5-2.6 mm.
  10. 10. The method for manufacturing a high-strength low-coercivity electromagnetic pure iron cold-rolled sheet strip according to any one of claims 1 to 9, comprising the steps of: Smelting and casting; Hot rolling; acid washing and cold rolling; continuous annealing, wherein the annealing soaking temperature is 630-670 ℃, and the soaking heat preservation time is 70-150 s; Leveling.
  11. 11. The method according to claim 10, wherein in the hot rolling step, the slab heating temperature is controlled to 1080 to 1140 ℃, the slab holding time is controlled to 150 to 240min, the finishing temperature is controlled to 790 to 830 ℃, and the coiling temperature is controlled to 520 to 560 ℃.
  12. 12. The method according to claim 10, wherein in the cold rolling step, the cold rolling reduction is 55 to 78%.
  13. 13. The method according to claim 10, wherein in the flattening step, the flattening elongation is 1.8 to 2.2%.

Description

High-strength low-coercivity electromagnetic pure iron cold-rolled sheet strip steel and manufacturing method thereof Technical Field The invention relates to strip steel and a manufacturing method thereof, in particular to electromagnetic pure iron cold-rolled sheet strip steel and a manufacturing method thereof. Background The electromagnetic pure iron is the earliest magnetically soft material in industry and is mainly used for parts such as relay iron cores, armatures, yokes, magnetic shields or shielding boxes and the like. Coercivity is a key property of a product and relates to the quality and service life of a relay. Compared with materials such as silicon steel, fe-Ni-Co and the like, the electromagnetic pure iron has low production cost and excellent formability, and is the material with relatively highest cost performance. In order to improve the electromagnetic pure iron performance, reduce the coercive force, the method for improving the purity of steel and reducing the unit density of inclusions can be adopted, but along with the improvement of the purity, burrs are easy to appear in the stamping process of the cold-rolled electromagnetic pure iron, and due to softer materials, the burrs are not easy to remove cleanly, the electroplating missing plating defect is easy to be caused, and the relay is invalid due to falling in the use process. In the prior art, the prior patent literature relates to the technical field: For example: the invention discloses a low coercivity free-cutting steel and a smelting method thereof, belonging to the technical field of special steel smelting and aiming at improving the free-cutting performance, the invention adds various alloys in steel, wherein Si content is 0.03% -0.05%, mn content is 0.5% -1.50%, P content is 0.0050% -0.15%, S content is 0.1% -0.50%, pb content is 0% -0.40%, and the steel easy to chip is obtained through converter and continuous casting by adding a large amount of inclusion forming elements. However, the invention does not explicitly refer to a specific average level of coercivity, but the description merely mentions that coercivity is below 250A/m. For example, the Chinese patent literature with publication number CN114438422A and publication day 2022, 5 and 6, named as "an electromagnetic pure iron and its manufacturing method", discloses an electromagnetic pure iron, whose chemical element composition includes (by mass) C not more than 0.005%, N not more than 0.008%, al 0.02-0.05%, ti 0.03-0.06%, si not more than 0.03%, mn 0.1-0.3%, S not more than 0.01%, P not more than 0.015%, O not more than 0.0035%, and chemical element mass percentage is in accordance with 5< [ Ti ]/([ N ] + [ C ]) <10. The electromagnetic pure iron has the characteristics of TiN, tiC and TiCN precipitates, and after magnetization annealing at the temperature of 830-850 ℃, the ferrite grain size is more than 100 mu m, and the coercive force is less than 48A/m. However, the component system of the invention is an IF steel component system, the Ti content is higher, and the upper limit of the P element is lower. For example, chinese patent literature with publication No. CN1211625A, publication No. 3/24/1999 entitled "production method of cold-rolled pure iron sheet with coarse grain structure" discloses a production method of cold-rolled pure iron sheet with coarse grain structure, wherein the chemical composition (weight percent) is C <0.01, si <0.1, mn 0.1-0.5, al <0.05, P0.02-0.1, S <0.01, N <0.005, O <0.015, and the balance of Fe, casting blanks of the above components are heated at 1100-1250 ℃, finally rolled at 850-950 ℃ to a specified thickness, coiled at 600-750 ℃, and finally annealed at 850-910 ℃ after one cold rolling. The invention can obtain coarse grain structure with the grain size below 3 of cold rolling final annealing and excellent soft magnetic performance with high magnetic permeability and extremely low coercivity by improving alloy components and hot rolling process. Disclosure of Invention The invention aims to provide high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel, which adopts an ultralow-carbon low-manganese design during steelmaking, and meanwhile, P is added to play a solid solution strengthening role, and the flatness is designed to be higher, so that the matrix strength of the pure iron cold-rolled sheet steel is improved, the magnetized annealed steel strip has lower coercivity, the burr height of a finished product can be effectively reduced during part stamping, and the stamping burrs are easier to remove. In order to achieve the above purpose, the invention provides a high-strength low-coercivity electromagnetic pure iron cold-rolled sheet steel which contains Fe and unavoidable impurities and further contains the following chemical elements in percentage by mass: C≤0.003%; Mn:0.05~0.25%; P:0.04~0.10%; O:0.005~0.016; 0<Al≤0.003%; Cu≤0.02%; Cr≤0.03%; Ni≤0.02%。 Further, in the high-strength low-coerciv