Recent advances on 316L+WC Composite Coatings Processed by Laser Cladding

Austenitic 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 at high temperature. Surface damage occurs in areas under contact loading. A composite coating in those zones appears as an interesting solution, combining the matrix material with hard reinforcements such as carbides. Among the possible reinforcements, WC or SiC are promising candidate due to their hardness, good affinity with iron-based materials and theoretical high melting temperature higher than 2200°C. Additive manufacturing, in particular laser cladding, is a suitable technique for the manufacturing of composite coatings with new properties, impossible to achieve with the classical manufacturing processes.
This work considers the recent improvements on a metal matrix composite composed by 316L and reinforcements of WC particles (20 in vol.%). In order to obtain more insights into the relative contributions of the various strengthening mechanisms and the evolution of the new microstructure during fabrication of thick deposits, macro-hardness tests and nano-indentations have been performed. Those results were correlated with scanning electron microscopy (SEM) to completely characterize the effect of the out-of-equilibrium phases formed around the original reinforcements (see Figure below) on the metallic matrix.