| 摘要 |
<p>The invention provides a high-strength hot-dip zinc-coated steel sheet which has a tensile strength of 590MPa grade, excellent surface appearance of coating, and excellent formability. A hot-dip zinc-coated steel sheet obtained by forming a hot-dip zinc coating layer on the surface of a steel sheet, which has a composition containing by mass C: 0.005 to 0.12%, Si: 0.7 to 2.7%, Mn: 0.5 to 2.8%, P: 0.1% or below, S: 0.07% or below, Al: 1.0% or below and N: 0.008% or below 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 or above and the ratio of the length of grain boundaries with precipitated inclusions to the whole length of grain boundaries is 50% or below 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> |
