| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a high-strength hot-dip zinc-coated steel sheet which has a tensile strength of 590 MPa grade, excellent surface appearance of coating, and excellent formability. <P>SOLUTION: The high-strength hot-dip zinc-coated steel sheet formed with the hot-dip zinc coated plating coating on the surface of a steel sheet has a composition containing, by mass%,≥0.005 to≤0.12% C.≥0.7 to≤2.7% Si,≥0.5 to≤2.8% Mn,≤0.1% P,≤0.07% S,≤1.0% Al, and≤0.008% Ni with the balance consisting of Fe and unavoidable impurities and a structure comprising at least≥90% of ferrite and 2 to 10% of martensite in terms of area ratio and in which the average Vickers hardness of the ferrite is≥120 and the ratio of the length of grain boundaries with precipitated inclusions to the whole length of grain boundaries is≥50% in the surface region of substrate iron spread at a depth of 3μm from the interface between the coating layer and the substrate iron on the substrate iron side. <P>COPYRIGHT: (C)2009,JPO&INPIT</p> |
