HIGH-STRENGTH GALVANNEALED STEEL SHEET SUPERIOR IN POWDERING RESISTANCE AND WORKABILITY

摘要

PROBLEM TO BE SOLVED: To provide a high-strength galvannealed steel sheet which has superior powdering resistance and shows an adequate balance between strength and ductility. SOLUTION: The galvannealed steel sheet comprises: a base steel sheet of a dual-phase steel sheet which has a predetermined chemical composition and has a metallographic structure that includes mainly a mixed structure of ferrite and martensite; and a plated layer of an Fe-Zn alloy formed on at least one side of the base steel sheet. The plated layer of the Fe-Zn alloy has a region which satisfies the relation of Al(atom%)/Zn(atom%)≥0.10 and is 300Åor thicker from the surface of the plated layer in a depth direction. COPYRIGHT: (C)2008,JPO&INPIT