Chip Formation Mechanisms When Cutting Amorphous Alloy with Cubic Boron Nitride Tools Based on Constitutive Equation Parameter Optimisation

Owing to potential inaccuracies in the current stress-strain curve used for constructing the Johnson-Cook (JC) constitutive model of amorphous alloys, the parameters of the JC constitutive equation were derived using Oxley's cutting theory, negative chamfer theoretical mechanics modelling, and the particle swarm optimisation algorithm. A two-dimensional finite element cutting model was subsequently established using AdvantEdge software. The optimised constitutive model was used to simulate the main cutting force (Fz) and the backward force (Fy), which resulted in average errors of 12.461% and 9.161%, respectively. Based on the optimised constitutive model in which the JC constitutive equation parameters were derived using Oxley's method, the variations in temperature, strain rate, and stress in the deformation zone during the cutting process were analysed. The chip microstructures revealed the transformation of lamellar chips into serrated chips resulting from a combination of plastic deformation, adiabatic shear, and shear slip.