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Ultrafine tungsten carbide (WC)–cobalt (Co) and WC–(Ti,W)C–Co end mills were produced via spark plasma sintering. The wear mechanism of these end mills during machining of AISI H13 steel was investigated. WC–Co exhibits good mechanical properties (HV30: 2110 kg/mm2, KIC: 10.4 MPa/m1/2, TRS: 1990 MPa). Although the high hardness of WC–Co makes it show excellent resistance to abrasive wear, it suffers from a significant adhesion problem. As the cutting temperature increases, the oxidation of the WC–Co causes damage to the microstructure of tool materials, which deteriorates the grain boundary strength and promotes adhesive wear. This phenomenon causes large areas of tool materials to chip off and eventually results in cutting‐edge breakage. The high brittleness of (Ti,W)C causes cracks to propagate at low‐stress levels, reducing the mechanical properties of WC–(Ti,W)C–Co (KIC: 8.8 MPa/m1/2, TRS: 1090 MPa). However, (Ti,W)C addition enhances the resistance to oxidation and workpiece adhesion, which reduces the tool material loss caused by adhesive wear. The tool life of WC–(Ti,W)C–Co is three times longer than that of WC–Co in milling of AISI H13 at the same cutting speed. The key to maximizing the mechanical properties of ultrafine cemented carbide tools when machining AISI H13 is the modification of anti‐adhesive wear of surface. [ABSTRACT FROM AUTHOR]

Two innovative ultrafine cemented carbide end mills, denoted C1 and C2, were synthesized through spark plasma sintering, featuring compositions of WC-8Co-0.4VC-0.4Cr 3 C 2 and WC-40(Ti,W)–8Co-0.4VC-0.4Cr 3 C 2 , respectively. Their wear behaviors were delved into during the precision machining of Inconel 718, and distinct disparities in wear evolution and tool longevity were unveiled. C1 exhibits exceptional wear resistance, surpassing C2 by a striking margin of 7.4–9.5, depending on the cutting speed employed. The sharp cutting edge of C1, characterized by a single hard phase of WC, minimal grain size, and high hardness, demonstrates excellent wear resistance and deformation resistance, thereby minimizing the onset of notch wear. In contrast, C2 experiences severe adhesive and diffusive wear phenomena, which culminate in substantial flank wear and cutting edge chipping. The addition of 40 wt% of (Ti,W)C exacerbates adhesion, flaking, and notch wear during machining. The prolonged and intensified adhesive wear witnessed in C2 leads to the deterioration of the tool surface and the formation of deep wear craters on the flank face. A comparison evaluation involving the prepared novel tools and commercially available end mills reveals that C1 boasts a longer tool life that outstrip those of its commercial counterparts by approximately 1.7–3.5 times under identical cutting conditions. • (Ti,W)C exacerbates adhesive wear, notch wear, and edge chipping of ultrafine WC-Co. • Unitary ultrafine WC is efficacious in sustaining geometry and sharpness of cutting edge. • Wear crater of flank face results from a combination of adhesive and diffusion wear. • Ultrafine WC-Co has superior performance than normal tools for milling Inconel 718. [ABSTRACT FROM AUTHOR]

Cutting performance and failure mechanisms of spark plasma sintered (SPS) ultrafine cemented carbides in dry turning Ti–6Al–4V were studied. The tools of UYG8 (WC-8wt%Co) and UYG8V2B10 (WC-8wt%Co-0.2 wt%VC-1.0 wt%cBN) exhibited higher lifetime and better processing quality than the commercial YG8 cemented carbide tool. The cutting distance of UYG-8 and UYG8V2B10 tools are 1.8 and 1.6 times longer than that of YG8, respectively. Cutting-edge breakage was found as the main failure forms of the SPS cemented carbide tools containing low Co content (≤6 wt%), whereas the SPS cemented carbide tools containing high Co content (≥8 wt%) exhibited flank and rake wear as main failure forms caused by abrasion, adhesion, diffusion, and oxidation. UYG8V2B10 tool wear mechanism was affected by cutting speed and depth. Wear mechanisms of UYG8V2B10 tool are mainly adhesive wear and oxidative wear at low cutting speed, but follow adhesive wear and diffusive wear at higher cutting speed. Moreover, with increasing cutting depth, tool failure forms are mainly breakage and chipping, largely induced by high cutting temperature and severe cutting vibration. [ABSTRACT FROM AUTHOR]

Ultrafine WC–Co cemented carbides with Co gradient were prepared by one-step (1300 °C/5 min) and two-step (1300 °C/3 min→1200 °C/5 min) spark plasma sintering. Effects of Co gradient and sintering process on the microstructure and mechanical properties were studied. The higher Co content of core layer provides the good fracture toughness and transverse rupture strength for graded cemented carbides, while the grain growth of surface caused by the migration of Co from the interior to the surface results in a slight decrease of surface hardness. Two-step sintering inhibits the grain growth and improves comprehensive mechanical properties of graded WC–4Co/WC–12Co/WC–4Co cemented carbide. Its surface grain size, hardness, fracture toughness and transverse rupture strength are 231 nm, 2080 kg/mm2, 8.93 MPa⋅m1/2 and 1829 MPa, respectively. In addition, the cutting performance of graded cemented carbides prepared by two-step sintering was investigated. The graded WC–4Co/WC–12Co/WC–4Co cemented carbide tool has a high wear resistance due to the high surface hardness, and its cutting edge has a good resistant capacity against breakage due to the high internal strength. It presents the longer tool life and higher machined surface quality than commercial YG8 tool. [ABSTRACT FROM AUTHOR]