单项选择题
A.造船用钢 B.锅炉用钢 C.压力容器用钢 D.气瓶用钢
A.0.40%~0.60% B.<0.40% C.0.60% D.>0.60%
A.<0.25% B.0.25%~6% C.>0.6% D.>0.8%