Hot-dip galvanized steel sheet with stable bake hardening performance and production method thereof

Abstract

The invention relates to a hot-dip galvanized steel sheet with stable bake hardening performance. The sheet is characterized by comprising the following chemical components of, in percentage by mass,0.0018 %-0.0033 % of C, less than or equal to 0.02 % of Si, 0.22 %-0.30 % of Mn, 0.015 %-0.025 % of P, less than or equal to 0.01% of S, 0.002 %-0.01 % of Ti, 0.002 %-0.01 % of Nb, 0.04 %-0.06 % of Als, less than or equal to 0.003 % of N, 0.0005 %-0.0015 % of solid solution C, and the balance iron and other impurities in the smelting process. According to the hot-dip galvanized steel sheet, the thickness is 0.5-2.5 mm, the yield strength is 180-240 MPa, the tensile strength is 290-360 MPa, the elongation percentage A80 is larger than or equal to 38%, the n90 is larger than or equal to 0.19, the r90 is larger than or equal to 1.9 and smaller than or equal to 3.0, and the bake hardening value BH2 is larger than or equal to 30 MPa, and in six months after a product is manufactured, the bake hardening value is kept in an effective range of 30-50 MPa. According to the steel, the problems that according to an existing low-strength ultralow-carbon bake hardening steel sheet, the bake hardening performance is unstable, the timeliness is poor, and the performance fluctuation caused by the poor timeliness can be solved, so that the stamping performance and the concave resistance of the material are effectively improved.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to a hot-dip galvanized steel sheet with stable baking hardening performance and a production method thereof. Background technique [0002] At present, the mainstream products in the automotive sheet market mainly include interstitial-free steel (IF), high-strength phosphorus-containing interstitial-free steel (IF-P) and bake-hardening steel (BH). Although IF steel with high plasticity can meet the requirements of complex stamping forming, its wide application is limited due to its low yield strength and poor dent resistance. In the past two decades, a variety of bake-hardening steels have been developed and applied by automobile manufacturers. Among them, ultra-low carbon bake-hardening steel plates are developed on the basis of traditional soft IF steels, which have the excellent properties of IF steels. Stamping and forming performance, after baking treatment, it can have bot...

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Problems solved by technology

Although IF steel with high plasticity can meet the requirements of complex stamping and for

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