A.w<0. 60-/0 B.w<2.1% C.0. 6%~2.1% D.w>2.1%
A.0.6%B.0.25%C.0.15%D.0.1%
A.低碳鋼 B.優(yōu)質(zhì)鋼 C.中碳鋼 D.高碳鋼