Wear behavior of laser clad 316L+WC composite coatings

peer reviewedAustenitic stainless steels (e.g. SS316L) are widely used due to their corrosion resistance and good toughness. However, their applications are still limited by their relatively poor tribological properties. A composite coating in zones subjected to contact loading appears as an interesting solution, combining the matrix material with hard reinforcements. Among the possible reinforcements, WC is a popular candidate due to its hardness and its theoretical high melting temperature of 2600°C. Laser cladding (LC) is particularly well-suited for the manufacturing of composite coatings, allowing for a large variability in raw materials. In LC, a stream of a powder, or a mixture of different powders, is fed into a focused laser beam while being scanned across a substrate, thus leaving behind a coating or object. This work considers a metal matrix composite composed by 316L stainless steel and reinforcements of tungsten carbides (WC) particles (10 and 20 in vol.%). During the fabrication of the coatings, the original WC particles dissolve partially in the melted SS316L matrix. The final microstructures are composed by the surviving parent WC reinforcements surrounded by a matrix that is itself reinforced as a result of the reactions with the original WC particles. The wear behaviour of those new microstructures are investigated by means of pin-on-disc tribometer tests and compared with SS316L reference samples also produced by LC. Profilometer measurements and SEM observations are carried out post-mortem on the worn samples to help elucidate the complex sequence of wear mechanisms at play during the tribometer tests