Evaluating the damage tolerant behavior of cold spray repaired aluminum alloys

Abstract

Cold spray presents a promising solution for repair of damaged material within high-value components. However, before employing cold spray for component repair, it is crucial to assess its damage tolerance and durability. This study focuses on evaluating the fatigue behavior of helium-sprayed AA6061 applied to an A356-T6 cast substrate compared to the same specimen geometry made entirely of the A356-T6 material. Fatigue testing was conducted using a marker band schedule to analyze fatigue crack growth rates in the cold spray and substrate materials. To complement the fatigue testing, experimental uncertainties and variabilities were incorporated into a crack growth model using a Monte Carlo approach to probabilistically assess reliability. The results indicate that the AA6061 cold spray material exhibited faster crack growth, resulting in a ∼25% lower life compared to the baseline A356-T6 material. Given the cost effectiveness of the cold spray repair process, it appears to be a viable approach, with the caveats that the residual life is expected to be less than the pristine substrate material and the cold spray interface is prone to delamination during crack impingement.