GALVANNEALED STEEL SHEET EXCELLENT IN SLIDABILITY

摘要

PROBLEM TO BE SOLVED: To provide a comparatively low-cost galvannealed steel sheet having good powdering resistance as well as good slidability and excellent in press- formability. SOLUTION: An atmospheric oxidizing treatment or a wet treatment with Zn ion-containing aqueous solution, is applied to the galvannealed steel sheet having the hot dip Zn-Fe alloy plated layer having the composition composed by mass % of 8-12% Fe, 0.05-0.25% Al and the balance Zn with impurities and noηphase to form the surface layer consisting essentially of Zn compound in the coated layer. Arithmetic mean roughness [Ra] on the surface is 0.5-1.5μm and Zn content [Zn] (mg/m2) in the surface layer satisfies formula (1): 0.285>0.0373×[Ra]+0.890×[Zn]-0.35.