A review of micro/nanostructure effects on the machining of metallic materials

Metallic materials have long been used in a wide range of industrial applications due to their outstanding physical and mechanical properties as well as high process latitudes. Mechanical machining is one of the important steps in manufacturing of metallic components because it directly influences the surface quality of the final products. To date, extensive studies have been conducted on the investigation of factors affecting the machinability of metallic materials, such as cutting parameters, cooling conditions and material micro/nanostructures. Contributory factors of cutting parameters and cooling conditions have been extensively reviewed in previous studies, but there is still a lack of a fundamental review to clearly understand the effects of material micro/nanostructures on the machining. Therefore, this review highlights the influences of different micro/nanostructures on the machinability and discusses the materials deformation mechanism in machining of metallic materials. The micro/nanostructures mainly include crystalline anisotropies of single crystals, grain sizes of polycrystals, phase compositions of single/multiphase materials, layer-by-layer structures of additive manufactured materials, amorphous structures of bulk metal glasses, micro reinforcements of metal matrix composites, and porosities of porous metal foams. Besides, the challenges and opportunities faced in machining of metallic materials are discussed from the perspective of micro/nanostructures.