A.普通碳素鋼 B.優(yōu)質(zhì)碳素鋼 C.滾動(dòng)軸承鋼 D.碳素結(jié)構(gòu)鋼
A.5% B.3.5% C.0.35% D.0.035%
A.工業(yè)純鐵 B.碳素鋼 C.生鐵 D.合金