Characterization of High-Density WC-Co Bulk Structures Fabricated by Selective Laser Melting

Abstract The objective of this research is to evaluate the feasibility of using a high energy laser-based additive manufacturing process to fabricate tungsten-carbide-cobalt (WC-Co) bulk structures that have properties comparable to those achieved by traditional fabrication methods. In particular, this work will investigate the properties and performance of these hard carbides densified by sintering alone, as compared to methods (such as hot isostatic pressing (HIP) and spark plasma sintering (SPS)) which impart simultaneous compaction and sintering. For this, a design of experiments was utilized to investigate the pertinent process parameter design space for the selective laser melting (SLM) process with a view to manufacture structurally-integral samples. Besides organizing qualitative observations, the effects of these process conditions were correlated with the resulting physical properties (viz., density, micro-scale composite hardness, and nano-scale hardness and Young’s modulus), as well as with microstructure and chemical compositions. Results showed certain samples with competitively-high densities, hardness and moduli, but with a large spread in properties, as is typical for such manufacturing processes; also, microstructural characteristics in line with desirable traits achievable via traditional methods was observed. Altogether, this work shows the promise of using SLM to fabricate bulk carbide structures.