Viscoplastic constitutive model for Ni-based directionally solidified superalloy: Experimental validation on notched specimen

Abstract

This paper aims to validate a viscoplastic constitutive model and investigate the local and the full-field strain of notched specimen. A high temperature digital image correlation (DIC)-based test system was constructed to measure the full-field surface deformation. Surface strain fields of notched DZ125 specimens were measured under monotonic tensile loadings at 20 °C, 650 °C, 760 °C, and 850 °C. Taking the effect of anisotropy, applied stress, and temperature into account, numerical simulations were conducted using a developed viscoplastic constitutive model. DIC-based measurements agreed well with the simulated strains, with the minimum correlation coefficient of 95.47%. Both the numerical and experimental results show that the area of notch plasticity increases with temperature and applied stress, and the high strain zone nearly remains constant under various tensile loadings. For a given notch geometry, the strain mutation in high strain zone nearly remains constant no matter how the temperature and the applied stress change.