Resistance of Si3N4 ceramic tools to thermal and mechanical loading in cutting of iron alloys

The Impact of Coating Layers and Additives on the Performance of Carbide Tools when Machining INCONEL 718 Superalloy

“…As the viscosity of the TaC grain boundary phase of the KC950 insert is higher than that in the KC850 insert, the diffusivity of the metallic elements in the grain boundaries is slower. The cutting performance of the KC950 insert remains stable as the potential contribution of chemical wear is moved to higher values of cutting speed, outside the speed range shown in table 3. The high viscosity of the nitrogen-rich grain boundary phases was equally important for the high temperature hardness.…”

“…;2.5ms1 the creater wear of the KC850 insert has an additional contributing factor that enhances wear. Chemical we'ar due to reactions between the tool and the metallic chip was observed with the KC850 [3]. The chemical reactions corrode the grain boundary phase and locally decrease the glass viscosity.…”

“…A continuous narrow layer that was observed at the trailing edge of the creater in the KC850 insert, which is mainly composed of cobalt, titanium carbide impurities (iron and calcium) and nickel, indicated chemical wear by local corrosion of the intergranular phase [3]. The mechanical effects of grain pull-out, ploughing and scoring of the reaction layer increase the reaction rates on the wear surface.…”

“…The cutting speed corresponding to the inflection point of the wear rate (table 3) can be used as a definition to limit the cutting speed of the WC inserts [3]. This speed limit is related to the onset of enhanced grain boundary corrosion, softening of the intergranular phase, grain pullout and intensive ploughing of the crater surface of the KC850 inserts.…”

“…Such is the case for an carbide tools insert when steel is turned; Inter-diffusion between the metal alloy and the tool materials [5-71, and serve abrasion by hard particles simultaneously occur as wear processes. The abrasive particles can either be tool material grains that come from rupture of the tool materials matrixafter intergranular chemical corrosion by the interfacial layer between the work-piece and the carbide tool rake face [3]-or chromium carbide precipitates from the nickel-based superalloy, Inconel 7 1 8.…”