Optimization of process parameters in cold metal transfer (CMT) welded dissimilar materials aluminium alloy and coated steel using RSM

Abstract

Joining of dissimilar materials (AA6061 and zinc-coated steel) is considered the greatest challenge because of poor metallurgical transition at joints. In the present investigation Cold Metal Transfer (CMT) process was used to improve weld shape and interfacial reaction in-homogeneity of aluminium alloy and galvannealed steel using ER4043 filler wire in lap joint configuration. We have identified three different input process parameters (current, welding speed and weaving length) with three different levels to optimize the process responses (area of bead, leg length and wetting angle).  The output or responses were measured using AutoCAD for all the 20 combinations given by the central composite designs (CCD) model in the response surface methodology technique. The tensile strength of the welded region was analysed. The mathematical models are obtained and evaluated for sufficiency using analysis of variance and other steps. The predicted and measured values are relatively identical, suggesting that the established models can be used to accurately predict responses in CMT welding of the Al to HSQ-GA dissimilar metals. The high responses (all) are correlated with the lowest welding speed and the highest degree of current, according to the contour plots of the process parameters. Welding speed was found to be the most important factor affecting the response variables analysed in the sensitivity analysis.