Fatigue and Fractographic Analysis of Artificially Aged 2618 Wrought Aluminum Alloy

Al2618 high-strength aluminum alloy was subjected to precipitation hardening at T6 tempering conditions to improve its mechanical properties for employing it as the spacecraft skin material. Nine specimens of Al2618 artificially aged alloy were prepared according to the ASTM-E606/E606M-12 standard and tested through the S-N curve method. It resulted in the fatigue strength of Al2618 being 150 MPa, which is better than the existing Al2024-T3 alloy by about 8.7%. An increment of 59.9% and 3.2% of fatigue life and fatigue strength for the infinite fatigue life of the alloy was identified through the Basquin Equation and Kohout-Věchet method, respectively, in correspondence with Al2024-T3. The fractographic analysis of the broken materials was investigated with the support of SEM images; the failure mechanism and causes for the failures were discussed.