Abstract
Grain boundary cavitation in Type 304 stainless steel under creep loading was investigated. Scanning electron microscopy observations showed that cavitation varied significantly among different grain boundaries even when they were similarly oriented to the stress direction. Drastic changes in cavitation were also often observed across twin boundaries intersecting a grain boundary facet; this finding indicated that grain boundary structure plays an important role in cavitation. The correlation between cavity density and boundary structure was characterized by high voltage electron microscopy and Kikuchi patterns. The results were analyzed in the light of modern grain boundary models. In general, cavities were found on most random high-angle boundaries, whereas coincident site lattice (CSL) boundaries tended to resist cavitation. Of the total boundaries (excluding twins), 53% were CSL boundaries; this percentage greatly exceeds available theoretical predictions based on random grain orientation.
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