Optimization of Fusion Zone Grain Size, Hardness and Ultimate Tensile Strength of Pulsed Current Micro Plasma Arc Welded Inconel 625 Sheets Using Genetic Algorithm

Nickel alloys have gathered wide acceptance in the fabrication of components, which require high temperature resistance and corrosion resistance, such as metal bellows used in expansion joints in aircraft, aerospace and petroleum industry. In case of single pass welding of thinner sections of this alloy, Pulsed Current Micro Plasma Arc Welding (PCMPAW) was found beneficial due to its advantages over the conventional continuous current process. The quality of welded joint depends on the grain size, hardness and ultimate tensile strength, which have to be properly controlled and optimized to ensure better economy and desirable mechanical characteristics of the weld. This paper highlights the development of empirical mathematical equations using multiple regression analysis, correlating various process parameters to grain size, grain size and ultimate tensile strength in PCMPAW of Inconel 625 sheets. The experiments were conducted based on a five factor, five level central composite rotatable design matrix. A Genetic Algorithm (GA) was developed to optimize the process parameters for achieving the desired grain size, hardness and ultimate tensile strength.