Manufacturing of die components from WC-15Co and WC-5Fe-5Ni-5Co alloys using dies obtained by photopolymer 3D printing

Introduction. Manufacturing steel or carbide dies is an expensive process, significantly impacting the cost of powder metallurgy products, especially in pilot and small-scale production. A promising direction is the use of additive manufacturing for tooling fabrication and the application of alternative, less expensive binders for cemented carbides. The purpose of this work is to investigate the feasibility of using additive manufacturing for forming die blanks from WC–15 Co and WC–5 Fe–5 Ni–5 Co cemented carbides and to conduct a comparative analysis of their phase composition, microstructure, density, hardness, fracture toughness, strength, and wear resistance. Methods. Die components (dies and punches) made of WC–15 Co and WC–5 Fe–5 Ni–5 Co alloys were fabricated by cold pressing of granulated powders in dies obtained by photopolymer 3D printing (Water Wash Resin 2.0, layer height 20 μm), followed by vacuum sintering at 1,400 °C. A comparative analysis was performed to evaluate the density, phase composition, microstructure, hardness, strength, fracture toughness, and microabrasive wear resistance of the obtained materials. Using the experimental cemented carbide dies, SNUM 120408 cutting inserts made of WC–6 Co cemented carbide were produced by cold pressing and sintering at 1,450 °C. The insert dimensions were compared with the requirements of GOST 19052 80, GOST 19042 80 and a commercial counterpart. Results and Discussion. The fundamental feasibility of manufacturing large sized cemented carbide die components (weighing up to 210 g) using photopolymer tooling has been experimentally confirmed. The relative density of the components was 99.1% for WC–15 Co and 98.3% for WC–5 Fe–5 Ni–5 Co, which is slightly lower than that of reference samples pressed at higher pressure in a steel die. It is shown that replacing the cobalt binder with a medium entropy Fe–Ni–Co binder suppresses WC grain growth (average grain size: 1.18 μm vs. 1.40 μm). This, together with the higher hardness of the binder, results in increased alloy hardness (1,070 HV vs. 1,010 HV) and a 10% reduction in the microabrasive wear rate. The manufactured dies produced cutting inserts whose geometric parameters (cutting edge length, thickness, corner radius) and physical and mechanical properties comply with the requirements of GOST 19052 80 and GOST 3882 74 and are comparable to commercial counterparts. Conclusion. The proposed approach, combining low cost photopolymer 3D printing for tooling fabrication with the use of a medium entropy Fe–Ni–Co bonded cemented carbide, enables the efficient production of functional cemented carbide dies for small-scale production. The WC–5 Fe–5 Ni–5 Co cemented carbide, exhibiting higher hardness and wear resistance, is a promising alternative to the standard WC–15 Co cemented carbide for these operating conditions.