High-strength hot-dip galvanized steel sheet with excellent spot weldability and stability of material properties

Abstract

A high-strength hot-dip galvanized steel sheet is provided which comprises a composite structure consisting essentially of ferrite and martensite. The steel comprises, by mass %, C: 0.05 to 0.12%, Si: not more than 0.05%, Mn: 2.7 to 3.5%, Cr: 0.2 to 0.5%, Mo: 0.2 to 0.5%, Al: not more than 0.10%, P: not more than 0.03%, and S: not more than 0.03%. The high-strength hot-dip galvanized steel sheet has not only excellent spot weldability, but also excellent “stability of material properties”, including tensile strength, total elongation, and yield strength, in a high range of strengths from 780 to 1180 MPa, even if the manufacturing condition (especially, the condition of the cooling process after annealing the steel sheet) is changed.

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