Optimised modelling of AISI 316L(N) material behaviour in the NeT TG4 international weld simulation and measurement benchmark

The NeT TG4 benchmark specimen consists of a three-pass type 316L Tungsten Inert Gas slot weld in a AISI type 316L(N) plate. Phase one of the finite element simulation round robin performed on TG4 by the NeT network made the assumption that weld metal exhibits the same mechanical behaviour as parent material. A comprehensive series of material characterisation tests on weld metal was performed by NeT participants, and these allowed the derivation of several sets of mixed isotropic-kinematic material model parameters specifically for weld metal. The derived models have been used to improve the predicted stresses in the TG4 benchmark specimen. This paper first reviews the weld metal materials testing programme, and then discusses the optimum material hardening model fitting strategy to use for austenitic weld metal. The derived material models are tested by using them to predict residual stresses in the TG4 benchmark, and validating the predictions against the extensive database of measured residual stresses.