| 摘要 |
PURPOSE:To manufacture the titled cold rolled steel sheet preventing the development of temper color by specifying the thickness of an oxide film on the surface of a cold rolled steel sheet having a composition prepd. by adding specified percentages of C, Si, Mn and Al to Fe. CONSTITUTION:The thickness of an oxide film on the surface of a cold rolled steel sheet having a composition consisting of, by weight, <=0.10% C, <=0.10% Si, <=1.0% Mn, <=0.10% Al and the balance essentially Fe is restricted to <=200Angstrom . The thickness is attained by regulating the dew point DT( deg.C) of atmospheric gas in an annealing furnace and the temp. T( deg.C) at which the steel sheet is taken out of the furnace so as to satisfy relation represented by an equation T<=0.7XDT+ 130. |
