HIGH-STRENGTH GALVANNEALED SHEET STEELS EXCELLENT IN POWDERING RESISTANCE AND PROCESS FOR PRODUCTION OF THE SAME

摘要

Disclosed is a high-strength hot dip galvannealed steel sheet having high powdering resistance produced by employing such a constitution that a Fe-Zn alloy plated layer is provided on at least one side of a basis steel sheet and a region in which Al (atomic %)/Zn (atomic %)‰¥0.10 is present in a thickness of 300 Å or more from the surface of the plated layer along the depth direction of the plated layer. Also disclosed is a hot dip galvannealed steel sheet whose formability is greatly improved by optionally specifying chemical composition and structure of the basis steel sheet.