| 摘要 |
PROBLEM TO BE SOLVED: To provide a hot dip galvannealed steel sheet capable of improving a boundary adhesion strength while being provided with well formability, and to provide a method for producing a hot dip galvannealed steel sheet by which its productivity can be improved. SOLUTION: The surface of the base metal of a steel sheet having a chemical composition containing, by mass, 0.030 to 0.25% C, 0.030 to 0.20% Si, 0.030 to 3.0% Mn,≤0.050% P,≤0.010% S,≤0.0060% N and 0.10 to 0.80% sol.Al, and the balance Fe with inevitable impurities is provided with a hot dip galvannealing layer comprising, by mass, 8.0 to 15% Fe and 0.15 to 0.50% Al, and, provided that the concentration of carbon in the base metal in the steel sheet within 5μm from the boundaries between the hot dip galvannealing layer and the base metal is defined as C1% by mass% and the concentration of carbon in the base metal of the steel sheet at the inside by≥200μm from the boundaries between the hot dip galvannealing layer and the base metal of the steel sheet is defined as C2%, C1 and C2 satisfy C1≥C2-0.030. COPYRIGHT: (C)2011,JPO&INPIT |
