Additive manufacturing of cemented carbides: Differences between beam-based and sinter-based technologies

Abstract

This review compares the microstructural defects and mechanical properties of WC-Co cemented carbides fabricated by beam-based additive manufacturing (BBAM) and sinter-based additive manufacturing (SBAM) technologies. BBAM methods, such as selective laser melting (SLM), use high-energy sources to melt powder layers, often leading to non-equilibrium phases, carbon/cobalt depletion, and inhomogeneous microstructures marked by alternating distributions of fine and coarse WC grains. These processes also introduce residual stress and brittleness due to non-uniform heating and rapid cooling. In contrast, SBAM methods, including binder jetting (BJT), yield microstructures resembling those of traditionally sintered materials, with improved consistency. While BBAM-processed parts typically suffer from porosity, cracks, and brittle phases, optimized SBAM-processed cemented carbides demonstrate fewer defects, though interlayer cracking remains a challenge. Mechanically, BBAM excels in fabricating intricate, high-precision components where hardness and wear resistance are critical. Conversely, SBAM is better suited for producing larger, geometrically complex parts requiring uniform microstructures and enhanced strength. Both approaches offer complementary advantages for specific applications in cemented carbide additive manufacturing. Future research should focus on refining additive manufacturing technologies and powder formulation techniques to minimize defects, improve dimensional accuracy, and enhance the mechanical performance, particularly strength, in fabricated cemented carbides.