The Influence of Heat and Holding Time on the Warm Forming of Al–Mg–Si Alloys

Warm forming of heat-treatable aluminium alloys can induce significant changes in their initial heat treatment, affecting both the forming process and the final in-service properties. This work aims to systematically investigate the influence of heat-holding time on the thermo-mechanical behaviour and post-forming properties of Al–Mg–Si alloys (EN AW 6016-T4 and EN AW 6061-T6), with a focus on optimizing process parameters to enhance formability and minimize springback. The study combines uniaxial tensile tests, cylindrical cup forming, hardness measurements, and springback evaluation, at room temperature (RT) and 200 °C, for different heat-holding times. The results show that short heat-holding times improve formability and reduce springback, while longer times promote artificial ageing, increasing strength and hardness but reducing ductility, especially in the EN AW 6016-T4 alloy. The EN AW 6061-T6 alloy exhibits greater thermal stability. The findings provide practical guidelines for industrial warm forming of Al–Mg–Si alloys, highlighting the critical role of heat-holding time in balancing formability, strength, and dimensional accuracy.