Patent ID: 8029915

Claim:
A highly corrosion-resistant hot-dip galvanized steel product excellent in surface smoothness and formability, having on the steel product surface a 10 to 350 g/m 2 zinc alloy plating layer consisting of 4 to 10% by mass of Al, 1 to 5% by mass of Mg, up to 0.1% by mass of Ti and a balance of Zn and unavoidable impurities, the plating layer having a metal structure in which one or more of the [Al phase], [Zn 2 Mg phase] and [Zn phase] are present in a mixture in the matrix of an [Al/Zn/Zn 2 Mg ternary eutectic structure], and the plating layer containing a Ti—Al base intermetallic compound composed of TiAl 3 in one or more of the [Al phase], [Zn 2 Mg phase]and [Zn phase], wherein the Ti—Al base intermetallic compound contained in an [Al phase] in the plating layer is present in a Zn—Al eutectoid reaction structure in which Zn phases are condensed, and the size of a dendrite in an [Al phase] in the plating layer is up to 500 μm.