Two Integrated Experimental and Modeling Approaches to Study Strain Distributions in Nickel and Nickel-Base Superalloy Polycrystals

摘要

This work presents two integrated experimental and modeling approaches for examining polycrystals at different length scales, which utilize different experimental techniques but the same elasto-crystal plasticity based finite element model (CPFEM). The goal of this work is to calibrate modeling approaches through experimental data, and then use the models to gain insight into the mechanics of deformation in nickel and nickel-base superalloy polycrystals. The first study utilized a micro-tensile test specimen of pure nickel with 259 grains, where the CPFEM simulations were initiated with the explicit 3D microstructure as measured with 3D-Electron Back Scattering Detection (EBSD) serial sectioning and compared with surface deformations measured with Digital Image Correlation (DIC). The second study utilized a larger polycrystalline nickel-base superalloy specimen with approximately 50,000 grains, where the CPFEM simulation results are compared with lattice strain data obtained through high energy x-ray diffraction utilizing a synchrotron x-ray source. In both cases the simulations are compared with different aspects of the experimental strain information (surface strain or lattice strain), and then the simulations are used to explore aspects of the heterogeneous nature of the deformation that are difficult or impossible to measure experimentally.