Application of grey relational analysis for optimizing weld bead geometry parameters of pulsed current micro plasma arc welded inconel 625 sheets

Pulsed current micro plasma arc welding (MPAW) is one of the most widely used welding processes in sheet metal manufacturing industry. In any fusion arc welding process, the weld bead geometry plays an important role in determining the mechanical properties of the weld and hence quality of the weld. Moreover, the geometry of weld bead involves several simultaneously multiple quality characteristics such as front width, back width, front height and back height, which must be closely monitored, controlled and optimised. This paper presents the optimization of the pulsed current MPAW process by using the grey relational analysis considering the aforementioned quality characteristics. The specific targets are maximum front width and back width, minimum front height and back height. Experiments were performed under different welding conditions such as peak current, base current, pulse frequency and pulse width using Inconel 625 sheets of 0.25 mm thick. A response surface method (RSM)-based central composite design (CCD) experimental design is used to conduct experiments. Optimal welding parameters were determined by the grey relational grade obtained from the grey relational analysis. Optimal results have been verified through confirmation experiments.