Experimental and Numerical Investigation of Double Pass Overlapping Beads by Twin-Wire Welding Additive Manufacturing Process

TWAM (twin-wire welding additive manufacturing) is a new additive manufacturing (AM) technology that uses gas metal arc welding (GMAW) to create metallic objects. Apart from greater deposition rates, twin-wire welding also allows for the creation of gradient objects with variable mechanical characteristics by using dissimilar filler wires. One of the most challenging problems to address is how to control thermal stresses while depositing many layers on the substrate plate. This research investigates residual stresses and distortion developed during weld bead deposition using finite element simulations (FES) and experimental approaches. Two additive beads with 32% lateral overlap were modeled in FEA software (ABAQUS) using the element birth technique. A passive coupled thermo-mechanical model was used to calculate the temperature gradient-driven residual stresses and distortion created during and after material deposition. Weld deposition was carried out with a twin-wire GMAW setup with online thermal monitoring using a thermocouple. The development of residual strains during weld bead deposition is influenced by temperature distribution. Residual stresses and distortion were quantified with X-ray diffraction (XRD) and a coordinate measuring machine (CMM). Experimental residual stresses and distortion have a good agreement with those found in FE simulations; this proves the numerical model to be accurate.