单项选择题
A.CrWMnB.5CrMnMoC.5CrNiMoD.60Si2Mn
A.莱氏体型耐热钢B.奥氏体型耐热钢C.贝氏体型耐热钢D.珠光体型耐热钢
A.20Mn2B.20CrMnTiC.20Cr2Ni4D.12Cr2Ni4