Mechanisms of Fatigue in Cemented Carbides at Elevated Temperatures

Cemented carbides are mainly used as cutting tools in various fields of application. In nearly all industrial uses they have to resist wear and concurrent complex thermomechanical loading, often including alternating mechanical loads at high temperatures. It has been shown that cemented carbides suffer lifetime-limiting fatigue under cyclic loads at 25 °C caused by subcritical crack growth. Present investigations show that strong, temperature-dependent fatigue effects occur in cemented carbides at elevated temperatures. TEM investigations revealed temperature-dependent processes that are responsible for the changes in the fatigue behavior: at low temperatures a phase transformation of the Co-binder phase and at higher temperatures oxidation in the cracks and brittle–ductile transitions of cubic carbides.