Effect of Cr3C2 on the microstructure and properties of WC-316L steel-bonded hardmetals fabricated by vat photopolymerization

Steel-bonded hardmetals integrate high hardness and outstanding toughness, making them widely used in molds and wear-resistant components. However, the fabrication of such materials with complex geometries via conventional powder metallurgy still poses considerable challenges. Vat photopolymerization additive manufacturing (VP-AM) provides a novel approach for producing high-precision cemented carbide parts with intricate structures, yet the role of grain growth inhibitors in this processing route remains unclear. In this study, the effect of the traditional grain inhibitor Cr 3 C 2 on the microstructure and properties of VP-AM-fabricated WC-316L steel-bonded hardmetals was systematically investigated. WC-316L slurries with 0, 0.3, 0.6, and 0.9 wt% Cr 3 C 2 were prepared, followed by VP-AM, debinding, and sintering. The slurry properties, printability, sintered relative density, microstructure, mechanical properties, and wear resistance were comprehensively characterized. Results show that the addition of Cr 3 C 2 up to 0.9 wt% does not compromise the shear-thinning behavior or sedimentation stability of the slurry. At an optimal Cr 3 C 2 addition of 0.3 wt%, the sintered relative density reaches a maximum of 99.0%, and WC grains are significantly refined—with the average grain size decreasing from 1.60 μm to 1.44 μm. Consequently, the material attains a hardness of 822.47 HV and a transverse rupture strength (TRS) of 1538.35 MPa, coupled with exceptional wear resistance. Excessive Cr 3 C 2 addition (>0.3 wt%) leads to performance degradation due to Cr segregation and reduced densification. This study clarifies the optimal addition content and mechanism of Cr 3 C 2 in the VP-AM WC-316L system, providing a valuable reference for composition design and process optimization of high-performance complex steel-bonded hardmetals.