Residual Stress in High-Velocity Impact Coatings: Parametric Finite Element Analysis Approach

High-velocity impact coatings are produced by techniques such as HVOF, HVAF, cold spraying, warm spraying, and supersonic plasma spraying. All these processes have in common the impact of particles at high velocities that produce peening of the surface and induce compressive residual stresses in the radial and axial orientations of the impact. If the process involves a significant heat input to the particles, quenching of splats and thermal mismatch between coating and substrate adds residual stress to the peening, and subsequently defines the final stress state. Through a parametric finite element model of coating formation, physical variables-including particle temperature and velocity, particle mass, particle morphology and deposition temperature-are studied to observe their effect on residual stresses, and define their possible manipulation to design coatings of desired average residual stress. To allow key parameter selection, a contour map of SS316 feedstock deposited on SS316 substrate is produced based on the parametric modeling of particle impact (via an explicit FE model) and the subsequent layer-by-layer coating formation (via an implicit FE model) employing ABAQUS(R) code. The Johnson-Cook model for high strain, strain rate and temperature is used as the constitutive equation for the study of impact and rapid cooling.