A.普通鋼 B.優(yōu)質(zhì)鋼 C.高級(jí)優(yōu)質(zhì)鋼 D.特級(jí)優(yōu)質(zhì)鋼
A.0.10~0.20% B.0.20~0.30% C.0.30~0.70% D.0.70~1.00%
A.0.045% B.0.035% C.0.030% D.0.020%