Role of secondary wire feeding in gas metal arc welding-based directed energy deposition process of low-carbon steel

Improvement of deposition rate for large-scale additive manufacturing is more convenient for increasing productivity. In the current work, secondary wire feeding in the existing gas metal arc welding (GMAW) system has been adopted to improve the deposition rate of low-carbon steel. A mathematical model is established to identify the feasible secondary wire feed rate for entrusting complete melting and uniform deposition using the arc energy of the GMAW process. The effect of current, deposition speed, and secondary wire feed rate on the deposition geometry are analysed systematically. The maximum feasible secondary wire feed rate for uniform deposition is achieved as similar to 3.15 m/min. The optimum utilisation of secondary wire feed enhances the bead height and wetting angle favourably and reduces the size of the remelting zone. The maximum bead height improvement (similar to 63%) and the uppermost penetration depth reduction (similar to 60%) is achieved at minimum heat input (i.e., low current and high deposition speed) of the GMAW system. The lowest bead width reduction (similar to 4%) is observed at high current and low speed (i.e., maximum heat input). However, the wetting angle improvement is found to be the maximum at moderate heat input (109 A and 600 mm/min). The enhancement of the highest deposition rate similar to 45% at low heat input (low current and high deposition speed) indicates the efficient secondary wire feed process utilisation in a GMAW system.