A.合金結(jié)構(gòu)鋼 B.合金工具鋼 C.耐熱鋼 D.球墨鑄鐵
A.08F鋼 B.40鋼 C.30Mn D.45Mn
A.表層56HRC,心部50HRC B.表層45HRC,心部20HRC C.表層56HRC,心部23HRC D.表層62HRC,心部42HRC