| 摘要 |
PURPOSE:To obtain a steel sheet capable of holding sufficient strength at a joint even if subjected to spot welding with a small current, by subjecting Mn steel having a specific composition to rolling and annealing in a furnace filled with a controlled atmosphere to form an oxide film. CONSTITUTION:The steel stock contg. <=0.2% C, 0.5-3.5% Mn, <=0.15% P, and <=0.01% S is subjected to hot rolling, pickling, and cold rolling. The sheet is then annealed in a furnace filled with an atmosphere in which the amount of hydrogen, etc., is properly controlled so as to form an oxide film of 100-500Angstrom thickness on the surface of the sheet. In this way, the steel sheet, which holds sufficient strength at a joint even if subjected to spot welding with such a small welding current that causes not any dust, can be manufactured at low cost without the addition of Si.
|
