Creep rupture as a result of grain boundary cavitation including void shape changes

Abstract

A model for creep rupture combining mechanisms of both grain boundary diffusion and dislocation creep of the surrounding grains is modified to include shape changes of voids initially existing or nucleating at grain facets. A further modification is to predict creep rupture times as a result of a criterion based on plastic limit-load at micro-necking of the intervoid matrix material. Creep of bars showing higher ductility, i.e. necking up to rupture is also considered. The validity of the suggested model is displayed through application to a large variety of metallic alloys for which the micro-mechanical data are mostly identified experimentally. Comparison among predicted rupture times and experiments of uniaxial and biaxial loadings shows fair agreement, in the case when continuous nucleation of voids is considered.