Modeling large-strain deformation behavior and neighborhood effects during hot working of a coarse-grain nickel-base superalloy

Isothermal, uniaxial compression tests and accompanying numerical simulations were conducted on Waspaloy-ingot specimens to quantify deformation heterogeneity during hot working of coarse, columnar-grain materials. This was used as a means to approximate deformation processing in ingot materials. Electron-backscatter-diffraction (EBSD) measurements were made before and after compression testing to quantify microstructure evolution. A crystal-plasticity finite-element-method model, in which the starting microstructure was instantiated using EBSD scans of the undeformed material, was used to simulate the deformation. Good agreement was found between observations and simulation predictions of specimen profiles and intra-grain misorientations. The simulation results also revealed that the grain neighborhood appeared to be a principal factor controlling the heterogeneity of deformation at the grain scale. Significant differences in the simulated deformation of a given grain were noted for various arrangements of the orientations of its neighbors. In particular, the first- and second-nearest neighbors of a given grain have the most significant effect on heterogeneous deformation behavior.