Fracture mechanics in the creep range

Abstract

Cracked high temperature components may fail by crack growth, net-section rupture, or some combination of both processes. This paper reviews the fracture mechanics concepts required to describe this behaviour. Procedures are presented for evaluating relevant characterizing parameters using experimental, numerical and limit analysis methods. Models for predicting crack propagation rates from uni-axial creep data involving ductility exhaustion in a process zone at a crack tip are outlined. Both the influence of build-up of damage in the process zone and material deterioration in the uncracked ligament are considered. It is shown that the models give satisfactory correlations with experimental data.