| 摘要 |
PURPOSE:To suppress the occurrence of the temper color on the high tension- cold rolled steel sheet containing much amounts of Si and Mn by suppressing the surface enrichment of Si and Mn in annealing process, electro-plating said steel sheet with the nickel of more than specified coating weight before continuous annealing. CONSTITUTION:The high tension-cold rolled steel sheet containing one or more kinds of Si and Mn and their total amount of more than 0.5wt%, is electro- plated with nickel before continuous annealing. The coating weight of said nickel plating is limited to 0.1g/m<2> when the total amount of said contained elements is 0.5wt%, and the coating weight is limited to 0.85g/m<2> when said total amount of the elements is 3wt%, and them the proportional relation defined by these two points in used as the lower limit value of the coating weight in the electro nickel plating. Consequently, the surface enrichment of Si and Mn in the annealing process is suppressed, thereby effectively suppressing the occurrence of the temper color on the steel sheet. |
