A multi-tier layer-wise thermal management study for long-scale wire-arc additive manufacturing

High heat input during layer-wise deposition in the Gas Metal Arc-based Wire-Arc Additive Manufacturing (GMA-WAAM) process leads to significant defects such as high residual stress and distortion. However, the choice of layer-wise heat input is constrained due to the requirement of an optimal set of weld parameters. It is essential to study the effect of heat input on the evolution and control of residual stress in the long-scale WAAM fabricated components. Therefore, this study investigates a novel multi-tier heat input strategy represented by four levels for a GMA-WAAM fabricated long-scale thin-walled component. Accordingly, a layer-wise single-, two-, three-, and four-tier heat input strategy in a twelve-layered long-scale thin-walled component is investigated for transient thermal and residual stress distributions through Finite Element Modelling (FEM). Further, a set of validation experiments was performed, which agreed with the predicted results. It is concluded that a reduced heat input during successive layer deposition greatly influences the cumulative heat input into the system. The twotier heat-input (case 2) system is found suitable among proposed case studies as an appropriate thermal management system with a variation of 6.98% in peak (melt pool) temperature and 198.4 ?C increase of minimum temperature during complete deposition. Also, the four-tier heat input (case 4) produced the component's lowest longitudinal and transverse stresses by 13.07% and 25.83%, respectively.