Preparation method of alloyed hot-galvanized dual-phase steel

Abstract

The invention provides a preparation method of alloyed hot-galvanized dual-phase steel, belonging to the technical field of high-strength cold-rolled hot-galvanized steel. Cold-rolled dual-phase DP steel comprises the following chemical components in percentage by weight: 1.3%-1.7% of Mn, less than or equal to 0.01% of P, 0.15%-0.25% of Mo, 0.15%-0.25% of Cr, 0.02%-0.04% of Nb, 0.07%-0.11% of C, 0.2%-0.5% of Si, 0.02%-0.07% of Als, less than or equal to 0.04% of N, 0.01% of S and the balance of Fe and impurities. According to the preparation method of the alloyed hot-galvanized dual-phase steel with excellent pore broadening performance, by adding a certain amount of Nb, martensite phases are refined and uniformly dispersed in a final microstructure; furthermore, by properly regulating the alloying temperature (520-560 DEG C), a proper amount of intermediate hard phase pearlite is generated, and the hardness difference between the hard martensite phases and a soft ferritic phase is reduced, so that the pore broadening performance of the dual-phase steel is improved.

Description

Technical field

[0001] The invention relates to the technical field of high-strength cold-rolled hot-dip galvanized steel, in particular to an alloyed hot-dip galvanized dual-phase steel and a preparation method thereof. Background technique

[0002] The microstructure of Dual Phase Steel (DP) consists of two phases, polygonal ferrite and martensite. Ferrite provides the ductility of the steel, and martensite provides the strength. The dual-phase steel has the characteristics of low yield ratio, high initial work hardening rate, and good strength and ductility matching, and has become one of the preferred materials for high-strength steel for automobiles. However, the soft matrix ferrite phase and the hard martensite phase of dual-phase steel easily form vacancies at the boundary, so there is a problem of poor hole expandability.

[0003] Different from the continuous annealing process, in the alloyed galvanizing process, the galvanizing temperature and alloying temperature hinder...

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