A Survey on Post-Weld Modification of Microstructural and Mechanical Properties of GTAWed Aluminum Butt Joints Through FSP and T6 Heat Treatment

Abstract

Fusion welding is a commonly applied manufacturing process in all fields of industry. Some imperfections (formation of coarse-grained microstructure, decrease in mechanical property, etc.) can occur especially in the fusion welding-based fabrication of aluminum alloys which have specific features, such as having high thermal conductivity, expansion coefficient, high hydrogen solubility in the liquid state, and oxide layer on the surface. Therefore, the enhancement of microstructure and mechanical properties in terms of the lifespan and strength of the fusion-welded joints is crucial for most applications. In the study, the effects of friction stir processing (FSP) and T6 heat treatment, applied as post-weld processing, on the weld zone properties of the gas tungsten arc welded (GTAWed) AA6082 plates were investigated. The effects of the post-weld processings (FSP and T6 heat treatment) on mechanical and microstructural features were analyzed via microstructural examination and microhardness measurements and tensile strength testing. It was observed that the dendritic microstructure in the processed region (stir zone) of the weld bead was destroyed and fine-grained microstructure was formed via FSP. Additionally, the findings showed that heat input occurred during FSP led to broaden of heat affected zone (HAZ) and decrease the hardness in a wider region. It was also determined that the mechanical characteristics of the GTAWed joint were increased but in contrast, the toughness was decreased through T6 post-weld heat treatment.