Prediction of Tensile Strength and Microstructure Characterization of Immersed Friction Stir Welding of Aluminium Alloy AA2014-T4

Abstract

Immersed friction stir welding is one of the variants of friction stir welding (FSW) in which work piece is completely submerged in the cooling medium. Immersed FSW of aluminium alloy AA 2014-T4 is carried out using tool shoulder diameter, rotational speed and welding speed as typical process parameters. The immersed condition of heat treatable alloy while FSW avoids the dissolution of strengthening precipitates normally observed in air FSW. The response surface methodology was used to develop the second order mathematical model for the tensile strength. Box-Behnken experiment design is selected for finding out the relationship between a tensile strength and welding parameters. The analysis of variance (ANOVA) is used to test the significance of fit of the equation. Confirmation experiments are carried out to validate the study and it is found that predicted results are in good agreement with experimental findings. Microstructure analysis of weld joint is also carried out to know the intrinsic reasons for the strength improvement in immersed FSW. The result indicates that tensile strength of weld joint obtained using immersed FSW is 307 MPa which is 75% of the base metal strength.