A. ≤2.5B. =2.5~8.0C. =8.0~14D. ≥14
A.1.6vm/sB.16vm/sC.1.6mm/sD.16mm/s
A.結(jié)構(gòu)鋼B.優(yōu)質(zhì)合金鋼C.高速鋼D.工具鋼