Evolution of residual stress and its impact on Ni-based superalloy

BB Xie and L Li and QH Fang and J Li and B Liu and ZW Huang and LM Tan, INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES, 202, 106494 (2021).

DOI: 10.1016/j.ijmecsci.2021.106494

Severe residual stresses generated by various preparative techniques can greatly affect the mechanical properties in the Ni-based superalloy parts. Limited data is currently available for deeply understanding the origin of residual stress at nanoscale and in particular, for establishing the relationship between the residual stress and mechanical property to accelerate the development of the Ni-based superalloys. Here, the effect of the heat treatment on the grain growth, residual stress and flow stress in Ni-based superalloy is investigated by using an atomic simulation combined with a physically-based theoretical model. The dissociation of grain boundary causes the coalescence of adjacent grains during annealing, which is observed by atomic simulation. However, this process is different from the previous work that the curvature-driven grain-boundary migration leads to the grain growth. The residual stress consists of the grain and grain boundary, where the average value from grain boundary is about 50% higher that from the grain based on the statistical result. The grain growth and local movement of grain boundary cause the stress relaxation, and in turn they reduce the residual stress. The evolution of the residual stress is in good agreement with the previous experiment. Further, an analytical theoretical model is proposed to qualitatively evaluate the variation trend of the residual stress with the annealing temperature. It is also proved that the residual stress decreases with the increase of the annealing temperature. The present work can be applied to determine the residual stress in the annealed structure, which greatly reduces the process flow, therefore provides a scientific basis to turn the technological process for the accelerated development of the new Ni- based alloys.

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