Characteristics of internal microstructures have a strong impact on the properties of particulate reinforced metal composites. In the present work, we perform finite element simulations to elucidate fundamental mechanisms involved in the ultra-precision orthogonal cutting of aluminum-based silicon carbide composites (SiCp/Al), with an emphasis on the influence of particle distribution characteristic. The SiCp/Al composite with a particle volume fraction of 25 vol% and a mean particle size of 10 μm consists of randomly distributed polygon-shaped SiC particles, the elastic deformation and brittle failure of which are described by the brittle cracking model. Simulation results reveal that in addition to metal matrix tearing, cutting-induced particle deformation in terms of dislodging, debonding, and cracking plays an important role in the microscopic deformation and correlated machining force variation and machined surface integrity. It is found that the standard deviation of particle size to the mean value has a strong influence on the machinability of microscopic particle–tool edge interactions and macroscopically observed machining results. The present work provides a guideline for the rational synthesis of particulate-reinforced metal composites with high machinability.
The residual stress of crystalline materials induced by deformation at grain level strongly correlates with crystal orientation. In the present work, the dependence of residual stress on crystallographic orientation in diamond cutting of polycrystalline aluminum is investigated by crystal plasticity finite element modeling and simulations. Furthermore, corresponding ultra-precision diamond cutting experiments, which have the same parameter setup with the finite element model, are also carried out. The crystallographic orientations of the specimens are depicted by electron back-scattered diffraction characterization, and the surface residual stress is measured by X-ray diffraction. Both experiment and finite element simulation results demonstrate the anisotropic characteristics of the residual stress within machined polycrystalline aluminum, which exhibits the significant correlation with crystallographic orientation. Furthermore, finite element simulations of bi-crystal cutting are also performed, which indicate that the grain boundary also has a strong influence on the generation of residual stress.
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