Advances in weld residual stress prediction: A review of the NeT TG4 simulation round robin part 1, thermal analyses

The members of the NeT network have undertaken parallel round-robin activities measuring and predicting transient temperatures, fusion boundary development, weld residual stresses and structural distortions in a benchmark specimen manufactured from AISI 316L(N) austenitic stainless plate with a central finite length slot filled with three superimposed TIG weld beads. This is a strongly 3-dimensional configuration with many of the characteristics of a repair weld. The round-robin finite element predictions of transient temperatures and the extent and shape of the melted zone are compared with thermocouple measurements made during welding, and with the results of destructive metallography. It is found that the majority of thermal simulations achieve high accuracy at weld mid-length, where quasi-steady state conditions apply, and slightly reduced but still acceptable accuracy at the bead ends, where thermal conditions are much more 3-dimensional. With two exceptions, variability in thermal solutions can be discounted as a cause of variation in subsequent mechanical simulations. The two outlier simulations allow investigation of sensitivity to final pass heat input and bead length.