Optimization of Laser Welding Process Parameters for AISI 316L to Ti-6Al-4V Dissimilar Joints Using RSM-MOPSO-TOPSIS Technique

Titanium and stainless steel are globally used in the aerospace and automotive sectors for their exceptional corrosion resistance and mechanical properties. Welding of these alloys is a big challenge due to the formation of brittle intermetallic layers at their joining interfaces. Traditional methods like ultrasonic and resistance spot welding are unsuitable because of their inability to control heat input, lack of flexibility, limited repeatability, and the need for physical contact between tools and workpieces. To overcome these problems, the laser welding method can be utilized to achieve a high-performance welded joint. In the present study, titanium (Ti6Al4V) and steel (AISI 316L) alloys have been welded using a solid-state fiber laser. The welding parameters, including laser power, beam offset, and welding speed, are optimized using Response Surface Methodology (RSM) integrated with the Multi-Objective Particle Swarm Optimization (MOPSO) technique. The RSM-MOPSO generates a set of optimal solutions. To quantify the best parametric set, TOPSIS (Technique for Order of Preference by Similarity to Ideal Solution) is further adapted from the Pareto front. The experimental results show that the beam offset and laser power greatly affect the ultimate tensile strength and microhardness of the welded joint, respectively. In addition, multi-objective optimization results are validated experimentally, which demonstrate optimal conditions at 1 mm/sec welding speed, 0.5 mm beam offset, and 328.50 W laser power to achieve superior ultimate tensile strength and microhardness of the welded joints.