Optimization of hybrid CO2 laser-GMA welding parameters on dissimilar materials AH32/STS304L using Grey-based Taguchi analysis

This study intended to verify the feasibility of laser-arc hybrid welding to dissimilar materials joints between high strength steel (AH32) and stainless steel (STS304L). For this, hybrid welding process for dissimilar materials was optimized by varying four parameters (welding speed, welding current, laser-arc distance, welding voltage) through Grey-based Taguchi analysis. A Grey relational analysis of the ultimate tensile strength (UTS), welding depth to width ratio (D/W) and absorbed energy (AE) attained from the Taguchi method can optimize the multiple-performance characteristics of the Grey relational grade. Moreover, hardness values microstructure and fatigue strength of welded joints fabricated under welding condition optimized by Grey-based Taguchi analysis were investigated. In the tensile test of welded joints, the damaged part was in BM of STS304L side. The hardness of welded joints exhibits within the acceptable range (the maximum value 340∼360 Hv). Dissimilar materials hybrid welded joints exhibited almost same fatigue strength for similar material STS304L SAW welded joints and lied well above the design curve(level D) for JSSC.