Binder jet additive manufacturing of tungsten carbide-cobalt tooling material

WC-Co based materials are attractive for tooling applications due to a combination of excellent hardness, high compressive strength, and wear resistance. Traditional manufacturing methods like powder metallurgy and extrusion can produce WC-Co components with low porosity but are limited in geometric complexity. Additive manufacturing, especially binder jet sdditive manufacturing has emerged as a promising alternative for fabricating complex geometries more efficiently. However, challenges remained, particularly with the formation of undesirable eta phases (such as W3Co3C and W6Co6C) during the sintering of WC-Co alloys, which degrade mechanical properties like hardness and toughness. To examine the wholistic effect of processing steps on microstructure and phase evolution, the current study investigated the fabrication of WC-10 wt.%Co via binder jet additive manufacturing with successive densification and post-processing steps, including sintering, hot isostatic pressing, as well as pack carburising. The sintered samples experienced partial decomposition of WC + Co into eta phases. Although successive hot isostatic pressing improved densification, it continued resulting in material predominantly consisting of eta phases. Whereas the pack carburising helped revert eta phases into WC + Co microstructure in both as sintered and hot isostatically pressed samples. The hardness of these samples was comparable to the conventionally fabricated WC + Co material.