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

摘要

PROBLEM TO BE SOLVED: To provide a high-strength galvannealed sheet steel excellent in powdering resistance. SOLUTION: The galvannealed sheet steel has an Fe-Zn alloy plating layer on at least one side of a steel sheet as basis material, and a region that satisfies the relationship of [Al(atomic%)/Zn(atomic%)≥0.10] exists in a depthwise thickness of≥300Åfrom the surface of the plating layer in the direction of thickness of the plating layer. The steel sheet as basis material to be used is exemplified by a dual phase steel sheet which has a prescribed chemical composition and in which a structure in the steel contains a matrix phase structure of ferrite and/or bainitic ferrite and a secondary phase structure of retained austenite. COPYRIGHT: (C)2007,JPO&INPIT