Residual Stress Development in Cold Spray Coatings: Insights from Curvature Measurements and Finite Element Analysis

Cold spray is a solid-state deposition technique in which particles adhere to a substrate through severe plastic deformation at relatively low temperatures, typically resulting in compressive residual stresses. However, recent in-situ curvature measurements have revealed unexpected instances of tensile residual stress development in cold-sprayed coatings. This study aims to quantify and elucidate the evolution of residual stresses in cold spray deposits through finite element modeling. Single-particle impacts of copper and AISI 316 stainless steel onto similar substrate materials are simulated under comparable process conditions to systematically investigate the interplay between impact dynamics, layer buildup, and post-impact thermal contraction. The comparison of materials with differing mechanical behavior highlights the influence of strength, strain-hardening characteristics, and strain-rate sensitivity on peening-induced compressive stresses, as well as the role of thermal mismatch in generating quenching-induced tensile stresses. Microstructural analyses support the numerical predictions, providing additional insights into the mechanisms driving stress evolution. By drawing parallels with residual stress profiles observed in conventional thermal spray processes, this work proposes a set of hypotheses to explain the emergence of tensile stresses in cold spray coatings.