Fatigue Life of Friction Stir Welded Joints in the Presence of Corrosion Damage: Experiments and Calculations

In this paper, the fatigue behaviour of pre-corroded 2024-T3 joints is investigated, as a first step toward assessing this problem. Unnotched specimens of 4 mm thick 2024-T3 base material and FSW joints were pre-corroded by alternate immersion in 3.5% NaCl solution, in accordance with ASTM G44 standards, for 100, 250 and 1000 hours. Subsequently pristine and pre-corroded coupons were tested under constant amplitude loading and lab environment at load ratio F /F of R = 0.1. The decrease of fatigue life due to corrosion damage was similar in welded and unwelded specimens. It is further shown that it is possible to estimate the fatigue life with a simple fracture mechanics model based on the parent material data and the maximum sizes of the corrosion damaged areas.