Study on pulsed wave mode laser welding of Nb-Zr-C alloy and many-objective optimization using meta-heuristic techniques

摘要

Laser welding was carried out in pulsed wave mode to analyze the effect of intermittent heating on the molten-pool thermal history, and metallurgical and mechanical properties of the welded joints of Nb-Zr-C alloy, a prospective structural material for coolant channels in compact high temperature reactors. This study deals with many-objective optimization aiming at improving the mechanical properties of laser welded joint. Duty cycle, welding speed and laser beam diameter were considered as the design variables during the many-objective optimization carried out using traditional composite desirability approach, Bonobo optimizer with weighted sum method and Non-Dominated Sorting Genetic Algorithm (NSGA-III). It led to yield the desirable strength, ductility and hardness properties of the welded joint. Experiments were carried out to validate the suggested optimal parameters obtained using the three techniques. Weighted sum approach combined with Bonobo Optimizer being an intelligent algorithm was able to more closely predict the experimental results compared to other techniques. Welded joint obtained using the energy density of 194.44 J/mm2 could yield the highest strength and elongation. Strength and ductility increased with an increase in energy density. Ultimate tensile strength of the optimized welded joint almost matched with that of the base metal. Moreover, a threefold enhancement in micro-hardness value was observed in the welded joint compared to that of the base metal.