Comparisons and contrasts in creep behaviour

Creep rate and ductility are uniquely related to stress, temperature and structure and correlations to assist in predicting the behaviour of many widely differing materials have emerged, particularly in the past four decades. Progress has also been made in the evaluation of anisotropic materials, on the influence of multi-axial stresses and of temperature changes. The extent and value of these correlations will be examined together with the identification of situations, especially in creep fracture, where chemical and microstructural features make predictive capability less reliable. The nucleation and development of creep damage continue to pose problems but useful information can be derived from experimental studies of notched specimens and from materials containing gas bubbles.