Formation of Cemented Tungsten Carbide Layer with Compositional Gradient Processed by Directed Energy Deposition

In order to partially improve the wear resistance for dies and jigs, layer-forming technologies for adding cemented tungsten carbide is effective way as an additive manufacturing technique. As one of the layer-forming technologies, directed energy deposition (DED) has attracted much attention from industry. However, many cracks are usually observed inside a formed layer processed by the DED due to the difference of material properties between an iron-based substrate and a cladded cemented tungsten carbide layer. In terms of durability of the formed layer, the crack formation is not preferable as well. In this study, as an attempt to suppress the crack initiation and propagation in cladded layers processed by the DED, formation of compositionally graded cemented tungsten carbide layer was performed by inserting a layer with low to medium tungsten carbide content between the substrate and cemented tungsten carbide layer. At first, single layers of cemented tungsten carbide having various tungsten carbide content were formed on iron-based substrates by the DED processing to understand the relationships between the tungsten carbide content and the number of formed cracks. By considering these experimental results, the compositionally graded cemented tungsten carbide layers were optimized. It was revealed that the crack initiation and propagation could be suppressed by compositionally graded cemented tungsten carbide layers.