A.M06 B.M09 C.M08 D.M05
A.普通碳素結(jié)構(gòu)鋼 B.優(yōu)質(zhì)碳素結(jié)構(gòu)鋼 C.碳素工具鋼 D.鑄造碳鋼
A.M03 B.M04 C.M05 D.M08