A review of the NeT Task Group 1 residual stress measurement and analysis round robin on a single weld bead-on-plate specimen

• NeT TG1 is the most comprehensive weld residual stress benchmark yet produced.
• The large measurements database allows statistical analysis of the measured stresses.
• The mean measured profiles are of great value for validating residual stress prediction techniques.
• The simulations database affords a unique insight into the sensitivity of predicted residual stresses to a variety of simulation variables.
• The most accurate predictions of stress are achieved using mixed isotropic-kinematic hardening models.

This paper reviews the European network NeT round-robin activities on measuring and simulating the residual stresses generated by laying a single weld bead on a flat austenitic steel plate. The activities are described, as are the main results obtained. From 2002 to 2010, fourteen independent sets of residual stress measurements were made using five different techniques, and subjected to detailed statistical analysis to evaluate best estimate profiles for validation of finite element predictions. In parallel, over forty finite element simulations were performed, examining a wide range of solution variables and their impact on the predicted residual stresses.This large body of work has allowed NeT Task Group 1 to develop a reliable thermal solution strategy. This is described and involves a global weld heat input calibrated against far-field thermocouples followed by derivation of detailed weld heat source characteristics by matching the weld fusion boundary profile. The accurate thermal solutions then allow the most important mechanical solution variables to be isolated and optimised. An important variable is found to be the material hardening model, with mixed isotropic-kinematic hardening being the most accurate for the AISI 316L plate material. Other solution variables, such as the welding efficiency, the mesh design and the thermal boundary conditions, are found to be of much less importance.The NeT TG1 specimen is described here in sufficient detail to serve as a benchmark for both finite element simulation and measurement of weld residual stresses.