| 摘要 |
<p>Disclosed is a steel material having excellent corrosion resistance, which is characterized by the following properties (A) to (C); (A) the steel material comprises the following components (by mass) as essential components: C: 0.02-0.15%, Si: 0.10-1.0%, Mn: 0.1-1.5%, S: 0.02-0.5%, Ti: 0.02-0.15%, Ca: 0.0001-0.01% and Al: 0.01-0.50%, and contains at least one component selected from Cu in an amount of 0.05-3.0% and Ni in an amount of 0.05-6.0%, with the remainder being Fe and unavoidable impurities, wherein the contents of Ni, Cu, S and Ti have the relationship represented by the following formula: [(Ni+4.5xCu)xSx2500xTi>5]; (B) the surface of the steel material is covered with a rust containing S in an amount of 0.3-5.0% by mass and further containing at least one element selected from Ti, Cu, Ni, Nb, Zr and V in the total amount of 0.5-10.0% by mass; and (C) a rust layer is formed on the surface of the steel material, wherein the crystallite size of a ß-FeOOH component in the rust layer is less than 50 nm as measured by the X-ray diffraction method, and the rust layer has a specific surface area of 10 m<SUP>2</SUP>/g or greater as measured by the molecular adsorption method.</p> |
