Welding thermal efficiency in cold wire gas metal arc welding

Cold wire gas metal arc welding (CW-GMAW) has been increasingly used in heavy-gauge manufacturing where high deposition rates are required. In such applications, the thermal efficiency of the CW-GMAW is crucial, yet it is not reported in the literature. Water calorimetry experiments were conducted to assess the thermal efficiency of CW-GMAW for two cold wire feed fractions and three common transfer modes: short circuit, globular, and spray, and these are compared to standard GMAW using the same transfer modes. The welds were produced using ER70S-6 as the electrode and cold wires. AISI 1020 plain carbon steel plates were used as the base metal with thicknesses of 9.53 mm and 6.35 mm. After producing the welds, three cross-sections were cut and analyzed using Vickers hardness maps, where differences were attributed to cooling variation rate across the weld cross-sections in high arc power samples. Results have shown that feeding a cold wire into the arc can re-introduce part of the lost heat back into the weld pool both in the short circuit and spray transfer regimes, suggesting an increase in the heat content in the weld pool.