Variation in as cast and aged structures of centrifugally cast heat resistant steel solidified in an electromagnetic field and under different cooling conditions

The influences of an applied electromagnetic field and cooling conditions on the as cast and aged structures of centrifugally; cast heat resistant HK40 steel tubes were investigated. The results reveal that both the electromagnetic field and the cooling ability of the casting mould have significant effects on the macrostructure morphology and the volume fraction and distribution of eutectic carbides, as well as on the homogeneity of secondary precipitation caused by high temperature aging treatment. The differences in the structures are attributed to the different solidification processes of the cast tubes. It is indicated that a reasonable combination of electromagnetic field and cooling conditions during solidification is greatly beneficial, leading to an improvement of creep resistance of cast tubes.