Effect of gas metal arc and cold metal transfer arc welding processes on microstructure and mechanical properties of AA8011-H18 alloy joints

Abstract The main objective of this study is to investigate the effect of gas metal arc welding (GMAW) and cold metal transfer arc welding (CMTAW) processes on microstructure and mechanical properties of AA8011-H18 aluminum alloy joints. The AA8011-H18 alloy sheets of thickness 3 mm were welded in butt joint configuration using conventional GMAW and CMTAW processes. The optical microscopy was employed for analyzing the microstructure of weld metal (WM) and heat-affected zone (HAZ) of the developed joints. The tensile properties and hardness of welded joints were evaluated using universal testing machine (UTM) and Vickers microhardness testing machine. The GMAW and CMTAW joints disclosed the joint efficiency of 58.33 % and 75.98 %, respectively. The CMTAW joints showed 30.25 % and 27.28 % improvement in tensile and yield strength compared to GMAW joints. However, there is a loss of 20 % ductility in CMTAW joints compared to GMAW joints. The superior tensile strength of CMTAW joints is correlated to microstructural refinement of WM and reduced grain growth in HAZ. It alludes to the wire retraction mechanism, which help to regulate the droplet transfer and lower the heat input.