TWI Industrial Member Report Summary 339/1987
By D J Smith
It is known that proof testing of components can improve their resistance to failure as well as demonstrating their integrity. For components containing cracks the overstressing technique can produce beneficial compressive residual stresses at the crack tips. Attempts to quantify the benefits of proof loading in terms of fracture mechanics have been principally directed at the lower shelf fracture behaviour of ferritic steels. The present report describes an extensive experimental study to examine the effects of prior overloading for temperatures spanning the whole transition regime. A number of loading conditions were employed on specimens made from a 50mm thick A533B steel. The specimens were oriented parallel and transverse to the rolling direction and a variety of crack depths were employed. The theoretical models to predict overload effects are also examined and compared with the experimental results.