In situ residual stress monitoring of various powder particle sizes and densities in kerosene HVOF-process

In situ residual stress resulted from various powder particle sizes and densities in kerosene HVOF-process

The use of in situ monitoring techniques, which are able to record curvature and temperature during spraying, has recently increased the understanding of the residual stress generation during the spraying process and allowed the ability to control the evolved residual stresses. It has been shown that processes such as HVAF and kerosene based HVOF processes generates higher peening stresses and final residual stresses (thermal mismatch, quenching and peening) is more compressive compared to lower kinetic energy HVOF systems. As the residual stresses may play a significant role on the mechanical response and fatigue behaviour of the coating, the understanding of these effects is detrimental for damage tolerant coating design. In current study the various particle densities and sizes has been studied to understand the effect of these variables on the residual stress built up. It was found that the particle density plays a significant role on the residual stress generation and difference arising only from particle density (same nominal particle size) the residual stress can vary 300 MPa. The combined effect from particle density and spray parameters was almost 600 MPa.