Wear and failure mechanisms of SiAlON ceramic tools during high-speed turning of nickel-based superalloys

Abstract Nickel-based superalloys have become one of the most promising and potential materials in gas turbine engine components contributing to aerospace industry due to their outstanding mechanical properties (high ductility, high temperate strength, etc.). However, the poor machinability (lower thermal conductivity, high work hardening, etc.) and low machining efficiency of nickel-based superalloys have further hampered it to be widely applied in the potential aerospace applications. In this work, we systematically investigated the effects of various cutting speeds (i.e. 100–400 m/min) on tool wear and failure mechanisms of the SiAlON ceramic tools in the dry cutting of nickel-based superalloys by performing high-speed turning experiments. The tool life and wear evolution with the cutting distance at various cutting speeds were studied; the response relationship of tool flank wear, cutting speed, and cutting distance was visually presented. The optimal cutting speed range could be 200 m/min∼300 m/min in our cutting conditions considering the tool life and the response relationship. Further, tool wear and failure mechanisms are demonstrated to be the adhesion, catastrophic fracture, and microcracks at flank wear land; and the micro-chipping is observed at rake face at a low cutting speed of 100 m/min. Additionally, at a higher cutting speed of 400 m/min, the wear and failure mechanisms are severe adhesion, cutting edge micro-chipping, microcracks, but none of catastrophic fracture failure. This disparity can be attributed to the different alternating dominant effects in strain hardening and thermal softening mechanisms behind the machining process.