Coarse cemented carbide produced via binder jetting 3D printing

Abstract

Until recently, cemented carbide produced via Binder Jetting 3D Printing (BJ3DP) resulted in microstructures with mixed WC grain size. Those materials exhibit excellent hardness and wear resistance but have transverse rupture strength that is lower than the strength of cemented carbide with a uniform grain size. The present investigation details the development of BJ3DP coarse tungsten carbide (WC-12%Co and WC-10%Co) that displays a sintered microstructure with uniform WC grain size. The free flowable (Carney flow <12 s/200 g) spherical powders exhibit very good printability and can be sintered to full density under standard sinter-HIP conditions (temperature 1460 °C, pressure 50 bar). The sintered mechanical properties compare well against cemented carbides produced by powder metallurgy. Vickers hardness, transverse rupture strength, and fracture toughness (determined by the Palmquist method) are in the range HV30 1050–1119, 2231–2684 MPa, and 18.8–19.4 MPa·m1/2, respectively. The wear properties were evaluated under abrasion and erosion using the ASTM B611 and ASTM G65 standard testing procedures. The wear resistance of the coarse BJ3DP cemented carbides compares well against conventionally produced cemented carbide. Parts over a wide range of sizes (from <1 g to 9 kg) and geometric complexities have been successfully printed and sintered with the new materials.