Evaluation of microstructure and mechanical behavior of Aluminum 2024 and Stainless steel 304 GTAW joints

This study aims to evaluate the microstructure and mechanical behavior of aluminum 2024 and stainless steel 304 dissimilar joints. The gas tungsten arc welding (GTAW) process has been employed to weld base metals by inserting copper-nickel-based (Cu-10%Ni) filler metal. The effects of GTAW parameters such as welding current, welding speed, and gas flow on microstructure and tensile strength have been analyzed through the Taguchi method. Results revealed that tensile strength is primarily influenced by welding current, followed by speed and gas flow rate. The excellent joint strength of 138 MPa has been achieved by using Cu-10%Ni filler metal. The optimal combination of parameters, i.e., welding current of level 2 (80 A), welding speed of level 1 (100 mm/min), and gas flow rate of level 3 (10 l/min), has been obtained through SN ratio optimization. Microstructure and EDS analysis depicted that the weld zone of a high-strength joint contained fine dendrites and CuAl and NiAl solid solutions, while the weld zone of a low-strength joint featured coarse dendrites and brittle FeAl phases.