40Mn与45Mn优碳钢有何区别板执行技术协议标准：WTB（舞钢企标）、GB/T71140Mn钢板化学成分熔炼分析牌号CSiMnPSCrNiCu40Mn0.37-0.440.17-0.370.70-1.00≤0.035≤0.03≤0.2≤0.3≤0.25 45Mn钢板化学成分熔炼分析牌号CSiMnPSCrNiCu45Mn0.42-0.500.17-0.370.70-1.00≤0.035≤…