| 摘要 |
PURPOSE:To prepare a zinc plated steel plate enhanced in weldability, by gradually cooling a molten zinc plating applied steel plate under a specific condition in an atmosphere containing a specific amount of oxygen. CONSTITUTION:A molten zinc plating applied steel plate is gradually cooled in a temp. ranging from 400 deg.C to 250 deg.C for 30sec or more within an atmosphere containing 1% or more of oxygen. In this case, when water is sprinkled to the surface of the steel plate, effect is enhanced and it is pref. to contain chlorides, sulfates or the like of various metals in water. In addition, the Al-concn. in a plating bath is pref. about 0.07-0.18wt%. By this method, a zinc surface layer is deactivated and mold dragging property in press pressing is further enhanced. |
