Direct laser metal deposition of tungsten carbide-cobalt-chrome (wc/co/cr) powder

Direct Laser Metal Deposition (DLMD) is able to realize, to repair and to restore, directly from the 3D CAD model, in a rapid and economic way, objects, moulds and tools, also with a very complex geometry, using a great variety of metals, including those very difficult to work with the conventional techniques. Moreover, this technique is well suited to produce very hard coatings. The objective of this work was to deposit layers of tungsten carbide–cobalt-chrome (WC/Co/Cr) powders on a substrate of AISI 316 stainless steel. WC/Co/Cr is a composite widely used as a wear-resistant material for cutting tools, moulds and coatings. Previous experimental studies performed on direct laser deposition of tungsten carbide showed considerable difficulties in processing this type of powder, mainly due to the partial or total lack of adhesion of the deposit to the substrate. In order to overcome this problem, the strategy of Functionally Graded Materials (FGM) was used. It consists in interposing layers of materials with variable composition between the substrate and the coating of tungsten carbide. Results showed that it is possible to obtain coatings of WC/Co/Cr with a good adhesion to the substrate and between layers, and with good mechanical properties