Surface engineering with lasers: an application to Co-base materials

The present paper concentrates on the applications of CO2 laser treatments to enhance fretting wear properties of stainless steel. Stainless steel 316 is used as substrate material. Powder particles of the various stellites with sizes ranging between 45 and 125 mu m are fed onto the surface. It was found that dilution of the substrate material with the clad material had a profound influence on the mechanical properties of the clad. The importance for this low level of dilution is that the powder blown onto the surface usually has an optimal alloy composition, which must not be altered. The overall pin-on-disc and fretting wear properties of Stellites are outstanding. The fact that the Stellite coatings tested are deposited using a high power laser beam seems to be a crucial improvement as far as the dense layer, low dilution, strong bonding and use of little material are concerned. Also, the laser depositing results in fine microstructures which may influence the oxidation rate and the oxide support from the substrate.