Machining of particulate-reinforced metal matrix composites: An investigation into the chip formation and subsurface damage

Abstract

This paper develops a microstructure-based model for investigating the mechanisms of chip formation and subsurface damage in the machining of particulate-reinforced metal matrix composites (PRMMCs). The morphology and distribution of the particles, the debonding of the particle-matrix interface and the fracture of particles and the matrix were comprehensively integrated into the modelling. The numerical analysis was also verified by relevant cutting experiments. It was confirmed that the established model can accurately predict the machining process, including chip morphology, subsurface deformation and cutting forces. It was found that the depth of cut significantly influences the machined surface integrity and cutting forces. Particle fracture mainly occurs along the primary shear zone in the cutting path. High strain and stress concentration induced by the extrusion of the cutting edge or large particles on the machined surface can also cause particle fracture beneath the cutting path. The brittle fracture of the particles located in the cutting path can form large cavities; while the deformed matrix material can partially cover these cavities to form a smooth surface. The matrix deformation occurs primarily along the shear plane, and the chip segments are separated easily along the plane with clustered particles. Serrated chips are formed in cutting the A359/SiC composite.