Optimisation of submerged friction stir welding parameters of aluminium alloy using RSM and GRA
C. Rathinasuriyan, V.S. Senthil Kumar
Abstract
Friction Stir Welding (FSW) uses friction and mechanical plastic deformation to heat and soften any weld material, allowing mechanical deformation comparable to extrusion and forging for enabling the formation of a highly strengthened joint. This paper reports the use of response surface methodology-based grey methods for the optimisation of the Submerged Friction Stir Welding (SFSW) process parameters, as joining the 6061-T6 aluminium alloy. The process parameters selected were the rotational speed (rpm), welding speed (mm/min) and water head (mm). Experiments were carried out on aluminium alloy using a servo controller FSW machine. The mechanical properties (average hardness and % of elongation) of submerged friction stir welded joints of the 6061-T6 aluminium alloy were investigated. The optimal welding process parameters for maximising the Avg.hardness and % of elongation were identified using the Grey Relation Analysis (GRA). Quadratic equation was developed for predicting the grey relational grade with good accuracy and fitted with adequate errors. The analysis of variance (ANOVA) was for testing to test the significance of the equation. The microstructural characteristics of the base metal and welded zone, as well as grain structure, were studied using scanning electron microscopy.