Exploring the impact of AGG on the strength of AA2014 aluminium alloy FSW joints

The AA2014 high-strength aluminium alloy was friction stir welded by way of optimal process parameters. Generally, the heat-affected zone is the soft region in all friction stir welding (FSW) joints, regardless of the materials involved. This zone is softer than other regions due to the dissolution of precipitates and the coarsening of strengthening precipitates caused by the thermal cycle. Post-weld heat treatment is an ideal process for reducing the soft region in FSW joints. In this study, a solution treatment with an artificial aging process was utilized to increase the strength of the joint. The experimental results revealed that the joints subjected to post-weld heat treatment presented greater strength (412 MPa) than did the joints subjected to as-welded heat treatment. The strength enhancement can be attributed to grain refinement, the uniform distribution of precipitates, and the occurrence of abnormal grain growth phenomena. The post-heat-treated joints demonstrated greater mechanical properties than did the as-welded joints because of the presence of stable grains in the stir zone.