单项选择题
A.1Cr18Ni9TiB.9SiCrC.CrWMnD.W18Cr4V
A.GCr15SiMnB.CrWMnC.20Cr2Ni4D.W6Mo5Cr4V2
A.HT250B.20CrMnTiC.QT600-3D.38CrMoAl