480mpa grade galvanized steel strip and its production method

Abstract

The invention discloses 480MPa-grade galvanized strip steel. The 480MPa-grade galvanized strip steel comprises, by mass, 0.05-0.09% of C, 0.05% or less of Si, 0.8-1.0% of Mn, 0.016% or less of P, 0.008% or less of S, 0.015-0.035% of Nb, 0.020-0.045% of Als, 0.007% or less of N, 0.015-0.035% of Ti, 0.0015-0.0030% of Ca, and the balance Fe. A production method comprises the steps that converter smelting and LF refining are conducted in a low-nitrogen mode; protective continuous casting is conducted, and nitrogen is controlled to be increased; and calcium treatment is conducted after refining is completed, wherein the mass percent of acid-insoluble aluminum in molten steel is smaller than or equal to 45 ppm, the ratio of the mass percent of the acid-insoluble aluminum to that of calcium is 0.5-1.5, and the ratio of the mass percent of the acid-insoluble aluminum to that of acid soluble aluminum is 0.05-0.20. According to the 480MPa-grade galvanized strip steel, the production cost is low, the overall mechanical performance of the product is superior, and the surface quality meets the requirements of FB surface levels in GB2518 and EN10346.

Description

technical field [0001] The invention belongs to the technical field of metallurgical plate production, in particular to a 480MPa grade galvanized steel strip and a production method thereof. Background technique [0002] With the growth of automobile production, people pay more and more attention to the emission of automobile exhaust. The application of high-strength steel in automobiles, on the one hand, is conducive to realizing the lightweight of automobiles and reducing automobile exhaust emissions; on the other hand, it also improves the safety of people in the car. More importantly, in order to ensure the corrosion resistance of automobile sheets, the use of galvanized automobile sheets is also increasing year by year, especially the demand for galvanized automobile sheets with a tensile strength greater than or equal to 480MPa is increasing day by day; The method of galvanized automobile sheet greater than 480MPa is mainly a phase transformation strengthening method ...

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Problems solved by technology

More importantly, in order to ensure the corrosion resistance of automobile sheets, the use of galvanized automobile sheets is also increasing year by year, especially the demand for galvanized automobile sheets with a tensile strength greater than or equal to 480MPa is increasing day by day; The method of galvanized automobile sheet greater than 480MPa is mainly a phase transformation strengthening method such as dual-phase steel, which is characterized by adding martensite forming elements such as Cr and Mo, and using phase transformation to improve the tensile strength of the steel; the cost of this process is expensive. At the same time, it has extremely high requirements on the rapid cooling capacity of galvanizing equipment, and it does not have the applicability for general promotion

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