Effect of Artificial Aging Conditions on Mechanical Properties of EN AW 6056 Aluminum Alloy

The 6xxx series aluminum alloys are preferred in many industrial applications because they can achieve relatively high strength levels through heat treatment. It is known that, as in the case of the EN AW 6056 alloy, the addition of small amounts of copper to materials in this series can further enhance their mechanical properties. In the current study, the effect of artificial aging conditions on the mechanical properties of EN AW 6056 aluminum alloy has been investigated. The ratio of Mg to Si and Cu content of the alloy were 0.939 and 0.92, respectively. The aging process was conducted at temperatures of 170, 180, and 190 °C, with corresponding aging durations of 1, 2, 3, 4, 6, 8, 12, 15, 18, 21, and 24 h. The maximum hardness was obtained in samples aged at 170 °C for 12 h, corresponding to the transition to over-aging condition. In contrast, the highest tensile strength was achieved in samples aged at 190 °C for 4 h, representing the peak-aged condition. Transmission electron microscopy (TEM) analyses revealed distinct microstructural characteristics for the peak-aged and transition to over-aging conditions. In the peak-aged state, needle-shaped β″ precipitates, lath-like Q′ phases, and L phases with narrow rectangular cross-sections were observed. In contrast, lath-like L precipitates were absent in the transition to over-aging condition.