High-Speed FSW Aluminum Alloy 7075 Microstructure and Corrosion Properties

Abstract

High-speed friction stir welding provides an opportunity to enable high-volume aluminum joining, thus lowering the expense of the process. To better understand this important industrial process the properties of the welds must be fully characterized. In this study we examined the microstructures of AA7075 butt welds with welding speeds of 1, 2 and 3 m/min. The welds were also tested for their corrosion resistance in a diluted EXCO solution at room temperature. The welds with higher speeds had a smaller corrosion sensitive area along with smaller HAZs, but the nugget zone became more corrosion susceptible. Their microstructure features were used to explain the non-uniform corrosion behavior across the weld. Both constituent particles and precipitate distribution were altered by the friction stir process and resulted in an overall sensitized weld affected region compared to the base material.