Characterizing residual stresses in rectangular beam specimens following thermomechanical loading

Abstract

Edge welding and partial quenching are explored as two processes capable of generating well-defined residual stress fields in beam specimens. The purpose of introducing residual stress fields into test specimens is to allow the influence of pre-existing residual stresses on the fracture behaviour of metallic components under applied loads to be studied in a systematic manner. Three materials are considered in this paper: two stainless steels (type 316H and Esshete 1250) and one ferritic steel (A533B). The paper presents both numerical and experimental results. The numerical results were obtained using finite element analysis, and the experimental measurements made primarily with the neutron diffraction technique, and also with X-ray synchrotron diffraction and incremental centre hole drilling. There was, in many cases, good agreement between predictions and measurements; however, there were several instances where finite element predictions differed significantly from measurements. This difference was often most pronounced close to the edge-welded or partially quenched specimen edge where the sensitivity of the numerical models to the assumed thermal and mechanical boundary conditions was greatest. The results presented confirm the usefulness of these two processes as a means of introducing residual stress fields into test specimens but highlight the need for experimental validation of numerical models. It is also demonstrated that, if a crack is subsequently introduced into the specimens, it is possible to generate both tensile and compressive crack-tip residual stress states.