The corrosion of refractory crucibles by a highly corrosive steel (18CrNiMo7-6) with a high aluminum content and casting temperature of 1 580 ℃ was investigated. The tested refractories were alumina, mullite and alumina doped with zirconia and titania (AZT). The samples were decreasingly attacked in the sequence AZT, alumina and mullite with corrosion layers of about 14, 6 and 1 mm, respectively. In the alumina and AZT, compositions corresponding to manganese aluminates and subsequently manganese aluminosilicates formed with manganese and silicon from the steel. In the mullite crucible, compositions corresponding to manganese aluminosilicates formed directly with manganese from the steel giving a highly viscous interfacial melt which retarded the further corrosion.