A.中碳鋼 B.高碳鋼 C.優(yōu)質碳素鋼 D.碳素結構鋼 E.碳素工具鋼
A.30%~50% B.50%~70% C.70%~80% D.80%~90%
A.精銑 B.精刨 C.精磨 D.手工刮研