A.低碳鋼B.中碳鋼C.高碳鋼D.普通碳素結構鋼
A.普通碳素鋼 B.優(yōu)質碳素鋼 C.高級優(yōu)質碳素鋼 D.低碳鋼
A.1/10~1/15 B.1/30~1/40 C.1/60~1/80 D.1/80~1/100