This study employed cold metal transfer (CMT) welding technology to repair defects in ZL114A aluminum alloy, investigating the influence of key repair welding parameters (preheating temperature, overlap amount, wire feed speed, welding speed) and ultimately obtaining defect-free repaired joints with relatively high tensile strength. Using a single-layer, single-pass bead-on-plate method, the effects of wire feed speed and welding speed on the spreading behavior of ZL114A melt on the substrate surface were studied. Through a two-pass, single-layer welding method, the influence of inter-pass overlap amount on the morphology of overlap welds was investigated. The effects of preheating temperature on the morphology, microstructure, and mechanical properties of the repaired specimens were examined by repair welding experiments on spherical crown grooves. The results indicate that to achieve favorable spreading of ZL114A droplets on the base material surface, the welding speed should be greater than 5 mm/s, and the wire feed speed should be within 7–9 m/min. When the overlap amounts are 65%, 70%, 75%, and 80%, the overlap welds are relatively flat, and lack-of-fusion defects are less likely to occur between the two weld passes. As the preheating temperature increases, the porosity defect rate in the repair weld decreases significantly, and the average grain size in the repair zone shows an increasing trend. The average grain size at the center of the repair weld is larger than that in the fusion zone. When the preheating temperature is 350 °C, no obvious porosity defects are observed in the repair weld. The proportion of high-angle grain boundaries increases significantly, and the maximum Kernel Average Misorientation (KAM) value also increases. The room-temperature tensile strength and Vickers hardness of the repaired specimens are superior to those of the original base material, with the tensile strength increasing by approximately 6 MPa and the Vickers hardness increasing by approximately 4 HV.
Shen et al. (Sat,) studied this question.