High-speed cutting performance characteristics of Ti(C, N)-W cermet tools against S32750 super-duplex stainless steel round bars

In this study, TiC0.5N0.5-60 wt% W and TiC0.5N0.5-70 wt% W cermet cutting tool specimens consisting of Ti(C, N) core, W-rich Ti(C, N) rim, and W-based alloy phases with much higher strengths than conventional heat-resistant tool materials at temperatures above 1673 K were fabricated by spark plasma sintering, electric discharging, and polishing. The cutting performance characteristics of the cermet cutting tool specimens were then examined and compared with those of commercially available NX2525, JX1, and HTi10 cutting tool specimens when cutting S32750 super-duplex stainless steel round bars under dry condition at a cutting speed of 800 m/min. The NX2525, JX1, and HTi10 specimens were TiC-Ni-based cermet containing Mo, Nb, and Co, WC-Al2O3-based composites, and WC-Co cemented carbide, respectively. The TiC0.5N0.5-70 wt% W and TiC0.5N0.5-60 wt% W cermet cutting tool specimens exhibited the first and second longest lifetimes among all the noncoated cutting tool specimens. The lifetime of the TiC0.5N0.5-70 wt% W cermet cutting tool specimen was extended by coating it with TiAlN film by physical vapor deposition. In contrast, the TiC0.5N0.5-60 wt% W and TiC0.5N0.5-70 wt% W cermet specimens exhibited compressive strengths much higher than those of the NX2525, JX1, and HTi10 specimens at 1973 K, whereas all the specimens exhibited similar compressive strengths at room temperature.