The Task Groups of the NeT European Network undertake closely controlled round robin studies examining the prediction and measurement of residual stresses in thoroughly characterised welded benchmarks. Task Groups 4 and 6 are examining three-pass slot welds in plates made from AISI316L(N) and Alloy 600 respectively. A very large body of independent RS measurements and simulations have been performed, giving a unique insight into the real-world reliability of both RS measurements and finite element simulation of welding. This paper reviews NeT Task Groups 4 and 6, and considers their
implications for modelling of welding processes.