Abstract
The microstructures of several centrifugally cast stainless steels containing strong carbide formers (Nb, Ti, and Zr) have been examined as cast and after prolonged creep in the range 800–1000°C. These additions refine the eutectic carbide, changing the morphology and composition as illustrated by the behaviour of IN 519 (Fe–Ni–Cr–Nb) and IN 519 TZ (Fe–Ni–Cr–Nb–Ti–Zr). The carbides present have been identified by electron diffraction and by energy-dispersive X-ray analysis. During creep, the precipitation of both MC and M23C6 carbides was observed, the former being very much finer and very resistant to coarsening. The role of both the grain-boundary carbide networks and the matrix precipitation in determining the creep properties is discussed.
MST/136
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