Molecular Dynamics Simulation of Nano-Cutting of Single-Crystal Nickel-Based Superalloy with Different Crystal Orientations

This study explores the novel nano-cutting mechanisms of nickel-based superalloys, with a particular emphasis on how crystal orientation and machining parameters — cutting depth and speed — affect shear strain, cutting force and temperature variations. Unlike previous studies that mainly focused on conventional cutting behaviors, this work employs molecular dynamics simulations to reveal previously unreported stress equilibrium phenomena and dislocation evolution trends in nano-cutting. Using nickel-based superalloy 718 as the research material, we systematically investigate the cutting process under various conditions through stress-strain analysis, cutting force evaluation and temperature monitoring. The results demonstrate that increasing the cutting depth leads to a significant rise in shear strain on the machined surface, while higher cutting speeds at a fixed depth further amplify shear strain, particularly in the tool-workpiece contact zone. Although different crystal orientations cause minimal variations in shear strain, they notably influence stress equilibrium, revealing a new phenomenon where increasing the rotation angle around the [100] axis exacerbates stress imbalances, leading to pronounced differences between grain boundaries and within grains. Additionally, the cutting force in the [100] direction is found to be the highest at varying cutting speeds, with a positive correlation observed between cutting force and cutting depth. At a constant depth, the cutting force in the [100] direction initially increases and then decreases with rising cutting speed. Furthermore, when the cutting speed reaches 200[Formula: see text]m/s, the density of [Formula: see text] (Shockley) dislocations progressively decreases with increasing cutting length, regardless of the cutting depth, which has not been thoroughly explored in previous studies. These findings provide new theoretical insights into the nano-cutting behavior of nickel-based superalloys, establishing a scientific basis for optimizing precision machining strategies at the nanoscale.