Modeling of Tertiary Creep in Copper at 215 and 250 °C

For a long time, only empirical models existed for creep curves in the tertiary stage. To understand the role of creep damage, including changes in the dislocation structure, cavitation, and necking, basic models that do not involve adjustable parameters have, however, recently been developed. These models were used to predict tertiary creep for copper at 75 °C. In the present paper, these models are applied to creep tests at higher temperatures (215 and 250 °C). These results demonstrate again that tertiary creep in copper is primarily controlled accelerated recovery of the dislocation structure and not by cavitation. The modeling results suggest that the role of cavitation is modest also in other creep exposed ductile alloys, which should be of importance to consider in the formulation of models for creep damage. Necking was only found to be of significance very close to rupture again in agreement with results at lower temperature.