| 摘要 |
<p>A hot-dip galvannealed steel sheet which comprises a steel sheet that has a composition containing, in terms of mass%, 0.02-0.30% C, 0.01-2.5% Si, 0.1-3.0% Mn, 0.003-0.08% P, up to 0.01% S, 0.001-0.20% Al, and 0.03-0.40% Ti, with the remainder comprising Fe and unavoidable impurities, and a zinc coating layer formed on each of the surfaces thereof in an amount of 20-120 g/m2 per surface, wherein each coating layer contains carbide grains having an average grain diameter of 10 nm or smaller in a number of 5-50 per section and oxide grains having an average grain diameter of 50 nm or larger in a number of 5-50 per section. The section means an area (t1×1 (µm2)) defined by the coating-layer thickness (t1 µm) and segments obtained by dividing a cross-section of the coating layer in the direction perpendicular to the thickness direction at an interval of 1 µm.</p> |
