Cutting mechanism of enhanced phase (gamma') in Inconel 718 based on strain gradient theory

摘要

Inconel 718 is one kind of nickel-based superalloy containing gamma(') precipitates (Ni3Al). It has been widely used in aerospace field due to its high strength, high oxidation resistance, and corrosion resistance at high temperature. Considering the influence of the strengthening phase gamma(') on the cutting deformation, and the inability of traditional classical mechanics to describe the characteristic scale of materials and to accurately explain some phenomena in the machining process, the model of enhanced phase gamma(') with cohesive element in cutting Inconel 718 is established in this paper. Moreover, the strain gradient theory is introduced to establish constitutive model. The effects of gamma(') phase on stress, strain, and temperature and the distribution of stress field at the crack tip are analyzed from the point of view of material micro-plasticity mechanics and material dislocation theory. The strain gradient strengthening effect is studied by changing the size of gamma(') phase.