Numerical modelling of geometry, residual stresses and thermal history in SS308L walls manufactured by WAAM on low alloy substrate

Abstract

This study presents a hybrid numerical modelling framework for predicting geometry, thermal history, and residual stresses in SS308L stainless-steel multiwall specimen manufactured by Wire Arc Additive Manufacturing (WAAM) on a low-alloy steel substrate. The model integrates macro-scale finite element thermomechanical simulation with analytical formulations for bead geometry, incorporating key physical phenomena such as Goldak double-ellipsoid heat source, and thermal expansion. Experimental deposition process was investigated under thermal camera. Simulated temperature histories at selected points demonstrated strong agreement with experimental thermal measurements, accurately capturing multiple thermal cycles associated with neighbouring bead depositions. Likewise, the numerical predictions of substrate distortion showed an average relative error below 5%, outperforming conventional macro-scale WAAM models. The simulated bead morphology locations closely matched the fabricated specimen, confirming the model’s capability to reproduce the overall bead morphology and macroscopic geometric deviations. The predicted residual stress distributions exhibited compressive and tensile regions qualitatively consistent with trends reported in previous WAAM studies. Since no direct residual-stress measurements were performed, these predictions should be interpreted qualitatively. Overall, the proposed study provides an efficient modelling framework for predicting thermal history, and distortion, while offering qualitative insight into macroscopic geometry and residual-stress evolution in WAAM components.