Manufacturing of WC-17Co 3D-objects by Laser Powder Bed Fusion followed by heat-treatment

Abstract

Conventional tungsten carbide (WC) cermet parts containing a cobalt matrix phase are generally produced via powder sintering. In this study it is shown that cermet parts can also be produced by laser powder bed fusion from WC-17Co powder precursor. Optimal process parameters were found for manufacturing without preheated building plate. Micro-structural analysis revealed noteworthy porosity fraction (1.41%) as well as the presence of small-scale cracks in the as-built specimens. It is further shown that most of these defects can be eliminated by heat treatment at ambient pressure or by hot isostatic pressing. Heat treatment also led to the dissolution of the fragile W2C phase. Hardness test results indicate that the performance of the AM parts was comparable to that of a reference produced via powder sintering. The work is a successful demonstration of manufacturing of cermet parts using laser powder bed fusion.