Application of TIG-MIG hybrid welding for wire arc additive manufacturing

Abstract

Wire arc additive manufacturing (WAAM) is an advanced 3D printing technology that fabricates metal components through layer-by-layer deposition using an electric arc as the heat source. However, excessive heat input during repeated thermal cycles in WAAM leads to microstructural coarsening, grain growth and phase instability, which adversely affect mechanical properties. This research aims to apply TIG-MIG hybrid welding in WAAM and compare its performance with conventional MIG welding. The methodology involved depositing four successive welding layers using both TIG-MIG hybrid and MIG processes. The parameters including, current (A), voltage (V), torch configuration, welding speed and wire feeding rate are investigated. The welds are characterized using optical microscopy to observe microstructura; changes and microhardness testing to evaluate the mechanical properties. Results showed that the TIG-MIG hybrid reduced heat input by 7.41% (from 621.00J/mm to 575.00 J/mm) across four layers, with surface temperature decreased from 195.4 ℃ to 231.4 ℃. The hybrid process produced nearly twice the reinforcement height (from 2.286 mm to 6.304 mm) compared to MIG, while the penetration depth decreased from 1.281 mm to 0.816 mm. Microstructural analysis revealed refined ferritic dendrite structures in TIG-MIG hybrid welds compared to the coarser dendrites observed in MIG. Although the TIG-MIG hybrid exhibited slightly lower hardness values (129.9 HV-221.57 HV) compared to MIG (168.17 HV-245.17 HV, the refined microstructure suggests improved toughness and mechanical ability. Overall, TIG-MIG hybrid welding in WAAM effectively mitigates excessive heat input, enhances bead geometry, and refines microstructure compared to MIG, making it a promising approach for improving the mechanical performance of multilayer WAAM components.