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High-strength aluminum alloys of the AA7xxx-series are increasingly used in demanding environments owing to their excellent strength-to-weight-ratio. The strengthening mechanism of these alloys is dependent on the precipitation of hardening particles, whose size, coherence, and distribution within the matrix may be altered using solid-state heat-treatments. The friction stir welding process strongly affects the precipitation formation due to its severe plastic deformation as well as the inherent time-temperature-cycle, ultimately influencing the hardness of the weldments. However, only limited understanding is available on the interrelationships of varying boundary conditions and the resulting microstructure with consideration of the precipitation behavior as well as incumbent hardness. Therefore, the current investigation seeks to depart from the state-of-the-art and to provide a holistic overview on these interrelationships using the example AA7020, welded using single- and multi-pin tools at air as well as under water atmosphere.

13th International Symposium, 21-23 May 2024, Session 4: Performance, Paper 02