Fatigue performance of cold spray repaired aluminium alloy 7075
Ali Alperen Bakir, R. P. Reed, Xiang Zhang, Abdul Khadar Syed, P.A.S. Reed, Phil McNutt, Matthew Doré
Abstract
• Cold spray-repaired specimens exhibited superior fatigue performance compared to their damaged (unrepaired) counterparts. • Fatigue cracks initiated at the substrate–cold spray interface due to crater formation caused by particle impact. • Numerical models provided accurate predictions for both unrepaired and repaired specimens. Cold Spray is a solid-state deposition technique where metal powder particles are accelerated to supersonic velocities by a pressurised gas jet, forming a solid-state bond with the substrate through rapid, localised plastic deformation. Recent advancements in cold spray have enabled its application as an additive manufacturing and repair technology. This study investigates the structural integrity of AA7075 specimens repaired using cold spray, focusing on the crack initiation mechanism and the influence of repair geometry on fatigue behaviour. Results showed that groove-repaired specimens exhibited improved much fatigue life. At lower stress levels (maximum stress 200–250 MPa, R ratio 0.1), repaired specimens demonstrated comparable fatigue performance to undamaged specimens, underscoring the effectiveness of cold spray patches in reducing stress concentrations. Fractography analysis revealed that cracks in the groove- and dent-repaired specimens consistently initiated at the substrate surface from small craters formed during particle impact. These findings highlight the potential of cold spray technology for extending the fatigue life of structural components.