Comparative experimental study on the modification of microstructural and mechanical properties of friction stir welded and gas metal arc welded EN AW-6061 O aluminum alloys by post-weld heat treatment

Abstract

In this paper, the effects of post-weld heat treatment on modification of microstructures and mechanical properties of friction stir welded and gas metal arc welded AA6061-O plates were compared with each other. Gas metal arc welding and friction stir welding were used as the applicable welding processes for AA6061-O alloys. The applied post-weld heat treatment consisted of solution heat treatment, followed by water quenching and finally artificial aging. The samples were classified as post-weld heat treated and as-welded joints. The microstructural evolution, tensile properties, hardness features and fracture surfaces of both as-welded and post-weld heat treated samples were reported. The results clearly showed that friction stir welding process demonstrated better and more consistent mechanical properties by comparison with the gas metal arc welding process. The weld region of as-welded samples exhibited a higher hardness value of 80 HV0.1 compared to the base material. In addition, the feasibility of post-weld heat treatment in order to enhance the mechanical properties and to obtain more homogeneous microstructure of 6061-O aluminum alloys was evaluated.