Predicting cleavage fracture in presence of residual stresses

Abstract

It is important to characterise the influence of initial residual stresses on cleavage fracture. Such stresses often arise from fabrication processes especially around welds, where the appearance of cracks is also a likely event. Using a specific crack configuration, this paper explores the stress state at the crack tip area under similar loading conditions with and without the presence of initial stresses as well as their interaction with mechanical loading. For various analyses, the stress fields are compared with their corresponding (i.e. at similar load) predicted probability of failure based on a statistical approach to cleavage fracture. A recently developed local stress based approach to failure probability prediction for cleavage fracture of ferritic steels is used to predict toughness distributions in presence of initial crack tip residual stress (RS) field. It is found that the influence of the induced RS field on final fracture depends on the extent and the level of the residual stresses.