Effects of Cr3C2 additive on the microstructure and mechanical behavior of binder jetting additive manufactured cemented carbides

In the binder jetting (BJ) additive manufacturing of cemented carbides, the abnormal growth of WC grains and the formation of coarse WC grain clusters pose significant challenges. This study introduces a novel approach to address these issues by incorporating micron-sized Cr ₃C ₂, a recognized inhibitor of WC grain growth, into spherical WC-17Co granules at varying concentrations for the BJ process. This method targets the inherent microstructural inhomogeneity of BJ-processed carbides. We systematically examined the impact of Cr ₃C ₂ content on the microstructure and mechanical properties of BJ-processed WC-17Co carbides. Our findings show that Cr ₃C ₂ effectively inhibits abnormal WC grain growth, enhancing the microstructural homogeneity of BJ-processed carbides. The average WC grain size was reduced from 1.57 μm in the plain WC-17Co to 1.39 and 1.35 μm with the addition of 0.5 wt% and 1 wt% Cr ₃C ₂, respectively. Concurrently, the hardness increased substantially to 1248 HV30 and 1232 HV30 with the same Cr ₃C ₂ additions, compared to 1149 HV30 for the plain WC-17Co. However, the addition of 0.5 wt% and 1 wt% Cr ₃C ₂ also led to a decrease in fracture toughness to 14.5 and 14.2 MPa·m ^1/2, respectively, from 17.5 MPa·m ^1/2 for the plain WC-17Co. Similarly, the transverse rupture strength decreased to 2151 MPa and 1993 MPa, respectively, from 2211 MPa for the plain carbide. Despite these reductions, the wear resistance was improved by 49.6 % and 15.4 % with the addition of 0.5 wt% and 1 wt% Cr ₃C ₂, respectively. Additionally, Cr ₃C ₂ enhanced the surface quality of BJ-processed WC-17Co carbides. The optimal microstructure homogeneity, high relative density, and favorable mechanical behavior were achieved with a 0.5 wt% Cr ₃C ₂ addition. These findings highlight the potential of Cr ₃C ₂ as a microstructural modifier in the binder jetting additive manufacturing of cemented carbides, suggesting a promising strategy to tailor the material properties for specific applications.