| 摘要 |
PURPOSE:To obtain desired strength on all steel plate materials regardless of plate thickness, by rolling the steel containing each prescribed amount of C, Si, Mn and Al at a prescribed temperature and by cooling it uniformly at a prescribed water amount density. CONSTITUTION:The steel comprising 0.3% or less C, 1% or less Si, 2.5% or less Mn, 0.1% or less Al and the remainder of Fe is heated at over 1,000 deg.C, and then the heated steel is rolled so that the temperature of the steel when its rolling is completed becomes under 900 deg.C. Subsequently, the rolled steel is cooled with water at a water amount density of 0.7+ or -0.3m<3>/min.m<2> per one side. The steel thus obtained has a constant level of strength on all plate thickness regardless of plate thickness. |
