Optimization of processing-microstructure-properties relationship in friction-stir welded 6061-T6 aluminum alloy

In this work, a simple but effective approach for improvement of strength of friction-stir welded 6061-T6 aluminum alloys was elaborated. It involves friction-stir welding (FSW) at relatively high tool rotational speed and welding speed followed by standard post-weld aging. The selected combination of FSW parameters provides high welding temperature as well as rapid cooling rate. This leads to complete dissolution of strengthening precipitates in stir zone but hinders their coarsening in heat-affected zone. In turn, this enables to avoid the formation of softened region during subsequent aging and thus substantially enhances strength and improves ductility.