Review and recent progress on developments of functionally graded WC-Co via a carburizing process: principles, insights, and industrial implications

Functionally graded WC-Co (FG WC-Co) offers enhanced property combinations and superior engineering performance compared to conventional homogeneous WC-Co. However, production methods face challenges in creating the graded microstructure, cost-effectiveness, and scalability. A versatile carburizing technique has been developed to address these challenges and to apply FG WC-Co to various WC-Co grades and applications. This paper reviews the carburizing technique's underlying principles and mechanisms of a one-step to a two-step process for treating off-the-shelf homogeneous products. Key two-step process parameters such as temperature, time, and carbon potential, which influence the control of the Co gradient, free carbon depth, and Co build-up, are highlighted. Both laboratory findings and field test data suggest that by optimizing these parameters, the carburizing technique can produce desired results, thus broadening the potential industrial applications of both the process itself and the FG WC-Co.