Measurement and Prediction of the Residual Stress Field in an Autogenously Welded Stainless Steel Plate

There has been a concerted effort over recent years to develop and refine finite element models of welds in order to predict residual stresses. These residual stresses are required to ever improved accuracies in order to provide continued confidence in the safe operation of ageing plant. Not only have computing hardware and software developed at a rapid rate, but guidelines for weld modelling ‘best practice’ have started to be documented. In order to validate and verify weld modelling procedures, test specimens are required which may be subjected to a suite of residual stress measurement techniques in order to allow comparison and ‘benchmarking’ of the numerical predictions. An abundance of such test specimens have been developed over the last few years. These are typically studied via large multi-national ‘round robins’ and results used to fine tune methodologies. A specific example is the NeT ‘bead on plate’ specimen [1, 2] which considered a single weld bead on an austenitic stainless steel plate. Whilst the major thrust worldwide now is to fabricate and study test specimens more representative of real plant, by considering larger specimens, many weld passes, different materials (including ferritic steels and their associated phase change during welding), the research presented in this paper considers an even simpler test specimen. Thus, an autogenous (no filler material) weld on a stainless steel plate is considered. There were two principal motivations for this work. Firstly, numerical and experimental results were required to validate analytical models of welding induced residual stresses. These analytical models [3] are currently under development but, to date, have been formulated only for parent material. Secondly, the lessons learned on weld modelling from previous studies were desired to be tested on the simplest test specimen available.