| 摘要 |
PURPOSE:To improve the weldability and corrosion resistance of a steel by successively applying a Cr plated layer, a galvanized layer, and a chromate layer at respectively specific amt. to the steel from the surface side. CONSTITUTION:A Cr plated layer at 10-300mg/m<2>, a galvanized layer at 0.1-5g/m<2>, or further a chromate layer at <=25mg/m<2> (expressed in terms of Cr) are applied to the steel sheet surface to obtain the tin-free steel for a welded can. The chromate layer is formed with a Cr oxide or the oxide and metallic Cr. Since inexpensive Zn and Cr are used in the tin-free steel, the cost of the steel is reduced, and the weldability and corrosion resistance are also improved. |
