单项选择题
A.CrWMnB.4Cr13C.W18Cr4VD.45Mn2
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