Research on the nanocutting mechanism of Ni-Fe-Cr-based superalloys: Conventional cutting versus UEVC

Abstract

To compare the nanocutting mechanisms using conventional cutting and ultrasonic elliptical vibration cutting (UEVC) of Ni-based superalloys, molecular dynamics simulations were used to simulate the nanocutting process. The effects of ultrasonic vibration frequency and phase angle on the material removal rate of workpieces under UEVC were investigated. The results showed that von Mises stress concentration occurred at grain boundaries under both conventional cutting and UEVC, although this concentration was more distinct under UEVC. At a higher ultrasonic vibration frequency, the material removal rate increased, and the surface quality of the workpiece was improved. 1/6<112>Shockley dislocations were the primary dislocation form of nanocutting, while dislocations with an unknown structure were the secondary form. The ultrasonic vibration frequency and the phase angle affected the 1/6<112>Shockley dislocation density in a fairly complex manner. At ultrasonic vibration frequencies lower than 100 GHz, the 1/6<112>Shockley dislocation density first increased and then decreased in all cases, but at ultrasonic vibration frequencies greater than 200 GHz, the 1/6<112>Shockley dislocation density first decreased and then increased in all cases. Overall, the coordination numbers displayed a normal symmetrical distribution centered at about 49.