| 摘要 |
A high-strength hot-dip galvanized steel sheet which includes a steel sheet that comprises major components and that contains at least 40 vol. % the sum of bainite and martensite, 8-60 vol. % retained austenite, and less than 40 vol. % ferrite, with the remainder comprising an incidental structure. The hot-dip galvanized steel sheet has, at the interface between the deposit layer formed by hot-dip galvanization and the base steel sheet, an intermetallic compound constituted of Fe, Al, Zn, and incidental impurities and having an average thickness of 0.1-2 μm, the intermetallic compound having a crystal grain diameter of 0.01-1 μm. After the deposit layer formed by hot-dip galvanization was removed, the surface of the base steel sheet has an arithmetic average roughness Ra of 0.1-2.0 μm and gives a roughness curve in which the contour elements have an average length RSm of 5-300 μm. Thus, a high-strength hot-dip galvanized steel sheet which includes a high-strength steel sheet as the base and which has excellent formability that can inhibit cracking or breaking is provided. |
| 主权项 |
1. A hot-dip galvanized steel sheet, which is a steel sheet comprising, in mass %,
C: from 0.10 to 0.4%, Si: from 0.01 to 0.5%, Mn: from 1.0 to 3.0%, O: 0.006% or less, P: 0.04% or less, S: 0.01% or less, Al: from 0.1 to 3.0%, and N: 0.01% or less, with the balance being Fe and unavoidable impurities, wherein the structure of the steel sheet further comprises, in terms of volume fraction, 40% or more of the total content of bainite and martensite, from 8 to 60% of retained austenite, and less than 40% of ferrite, with the balance being an unavoidable structure, and alloying hot-dip galvanization is applied to the steel sheet surface, and the hot-dip galvanized steel sheet has a layer of an intermetallic compound composed of Fe, Al, Zn and unavoidable impurities at the interface between the hot-dip galvanized layer and the underling steel sheet, the average thickness of the intermetallic compound is 0.1 to 2 μm or less, and the crystal grain size of the intermetallic compound is 0.01 or more to 1 μm or less, and the arithmetic mean roughness Ra of the underlying steel sheet surface after removing the hot-dip galvanized layer is 0.1 or more to 2.0 μm or less, and the average length RSm of the contour curve element in the roughness curve is 5 or more to 300 μm or less. |
