Residual stresses in high-velocity oxy-fuel thermally sprayed coatings - Modelling the effect of particle velocity and temperature during the spraying process

The application of thick thermally sprayed coatings on metallic parts has been widely accepted as a solution to improve their corrosion and wear resistance. Key attributes of these coatings, such as adherence to the substrate, are strongly influenced by the residual stresses generated during the coating deposition process. In high-velocity oxy-fuel (HVOF) thermal spraying, due to the relatively low temperature of the particle, significant peening stresses are generated during the impact of molten and semi-molten particles on the substrate. Whilst models exist for residual stress generation in plasma-based thermal spray processes, finite element (FE) prediction of residual stress generation for the HVOF process has not been possible due to the increased complexities associated with modelling the particle impact. A hybrid non-linear explicit-implicit FE methodology is developed here to study the thermomechanical processes associated with particle impingement and layer deposition. Attention is focused on the prediction of residual stresses for an SS 316 HVOF sprayed coating on an SS 316 substrate.