Prediction of Residual Stress Buildup in Cold Spray Deposits using a Macroscale Finite Element Deposition Model

Residual stresses in cold spray deposits play an important role in such performance characteristics as strength of deposit-substrate interface, post-spray part distortion, tensile strength, and fatigue life. Developing tools for predicting residual stress formation in cold spray deposits is essential for mitigating/leveraging residual stress buildup for service performance. This study presents the use of a macroscale, thermomechanical finite element model for predicting cold spray residual stresses during deposition. The deposition process is simulated by progressive activation of material blocks as the deposit material is laid down. The effect of heating due to surface impingement of the hot nozzle gases is modeled using a heat flux distribution derived from computational fluid dynamics simulations. Heat generation and stress buildup due to particle plastic deformation during impact are incorporated from multiple particle impact simulations. The model is verified against X-ray diffraction residual stress measurements taken on cold-sprayed aluminum and copper deposits. The observed agreement between the experimental and simulation results suggests that this approach is an effective means of predicting the residual stresses in cold spray deposits and provides a tool for helping to understand and mitigate/leverage residual stress buildup in cold spray deposits.