Optimization of hardness, tensile strengthand fatigue life of micro plasma arc welded super duplex stainless steel UNS S32750 using grey relational analysis

The current work uses Micro Plasma Arc Welding to butt weld 0.33 mm thick Super Duplex Stainless Steel (UNS S32750) sheets. In addition to welding input parameters including peak current, base current, pulse rate, and pulse width, consideration is given to the hardness and ultimate tensile strength of the welded joint. When applying central composite design (CCD), five tiers of weld input parameters and four criteria are considered. To comprehend how output responses vary as weld input parameters vary, main charts are generated. Mathematical models that account for linear functions are built using the MINITAB application. Analyzing Variance (ANOVA) is done with a 95% confidence level. Grey Relational Analysis is used to determine the best combination of weld input parameters by optimizing hardness, ultimate tensile strength, and fatigue life. The optimal parameters combination was determined as peak current at 20 A, base current at 10 A, pulse rate at 40 pulses/s and pulse width at 30%. Additionally, the relative relevance of the weld input parameters is determined.