Patent ID: 7396420
Filing Date: 2008-07-08
Classification: C21D,C22C,C23C,Y10T

Abstract:
1. A hot-dip galvanized steel sheet excellent in press-formability and strain age hardening property as represented by a ΔTS of 80 MPa or more, comprising: a hot-rolled steel sheet having a chemical composition comprising, in weight percentage: 0.05 to 2.0% W, and the balance Fe and incidental impurities and having a structure with a ferrite phase as a main phase forming a composite structure with a secondary phase containing a martensite phase in an area ratio of 2% or more and a fine carbide of W is strain-induced-precipitated in martensite in the secondary phase after a heat treatment at a temperature within a range of 150-350° C., which follows a pre-deformation of 5% or more; and a hot-dip galvanizing layer or an alloyed hot-dip galvanizing layer formed on a surface of the steel sheet.