A.工具鋼 B.合金滲碳鋼 C.優(yōu)質碳素結構鋼 D.濾動軸承鋼
A.不銹鋼 B.合金工具鋼 C.中碳合金鋼 D.合金結構鋼
A.16Mn B.40Cr C.14MnMoV D.20CrMnTi