Studies on Dissimilar Twin-Wire Weld-Deposition for Additive Manufacturing Applications

Due to its high deposition rate, low cost and simple setup, weld-deposition based additive manufacturing is slowly evolving into a viable alternative for creating meso-scale applications. There is also an increasing demand for creating functionally gradient objects with varying properties. Gas metal arc welding based twin-wire weld-deposition presented here makes it possible to create functionally gradient objects with varying mechanical properties like hardness. This is achieved by using separate filler wires of different composition and controlling the proportion of each wire separately. The current work presents a proof of concept of the twin-wire weld-deposition and also the primary experiments carried out for understanding the effect of weld-deposition process parameter on bead geometry. Two filler wires viz., ER70S-6 and ER110S-G, the former having lower hardness than the latter, were used for the experimentation. The range of process parameter for different combinations of these filler wires was determined and the operating range of the same was identified. Subsequently, the criterion for adapting the twin-wire welding from joining to weld-deposition of a complete layer like thermal steady-state condition, effect of torch direction and effect of overlapping beads have also been studied.