Shot peening effect on the morphology and roughness of HVOF coatings

The HVOF process is characterized by low porosity and oxide content and particles with high kinetic energy, resulting in a high density coating. However, the presence of non-melted particles can affect the porosity, tensile adhesion, hardness and surface finishing. In this article, the influence of the shot peening treatment on morphology, porosity, tensile adhesion and roughness of some  FeMnCrSiNi HVOF coatings have been studied. High carbon steel particles with spherical geometry were used for shot peening. The results show that the shot peening reduces the porosity, mainly in the coatings with higher porosity level, and generates an increase of hardness with no phase transformations. The increase in adherence is also a benefit generated by the treatment. The optical profilometry analyze a significant roughness reduction. With shot peening a compression residual stress were performed on the coating, improving mechanical properties and a low surface roughness.