Additive manufacturing of WC-Co cemented carbides: Process, microstructure, and mechanical properties

Cemented carbides, known as the "teeth of industry", are widely used in aerospace, resource mining, equipment manufacturing, rail transit, and electronic information industries, among others. Additive manufacturing (AM) technology provides a new route for preparing geometrically complex cemented carbide parts. In this paper, we review the progress in respect of AM technology in WC-Co cemented carbides. We first introduce the two technology routes for AM of WC-Co cemented carbides: powder bed fusion (PBF), based on hot forming technology (e.g., selective laser sintering, selective laser melting, and selective electron beam melting), and forming–debinding–sintering (FDS), based on green-body cold forming along with debinding and sintering processes (e.g., binder jetting additive manufacturing–debinding–sintering, fused deposition modeling–debinding–sintering, and 3D gel printing–debinding–sintering). Furthermore, we analyze the key influencing factors in respect of the densification, metallurgical defects, microstructure evolution, and mechanical properties of WC-Co cemented carbides prepared using AM. We conclude that the critical problem in preparing WC-Co cemented carbides via PBF is the prevention of cracking and reducing porosity to improve the relative density, as well as avoiding the η phase. However, although FDS has shortcomings, including complex feedstock preparation (binder) and a long technological process, this technology shows promise for preparing high-performance WC-Co cemented carbides, because it sufficiently combines the advantages of AM and powder metallurgy. Finally, we identify and delineate the current research gaps and prospects of AM in respect of WC-Co cemented carbides from four aspects.