High-Energy Diffraction Microscopy (HEDM) was employed to measure and compare the evolving micromechanical state of two alloys, an austenitic stainless steel (316 L) and nickel-based alloy (Inconel 625) fabricated by both conventional methods and powder metallurgy with hot isostatic pressing (PM-HIP) during in situ uniaxial tensile testing. Each of the four materials was tested through the elastic regime to just beyond yield. HEDM was performed at room temperature in the far-field (ff) configuration at the Cornell High Energy Synchrotron Source to measure grain-average elastic strains and subsequently derive stress tensors. The evolution of the normal stress component along the loading direction in individual grains as a function of macroscopic deformation is presented. Initially, grain-scale stresses in the loading direction are more heterogeneous in the wrought alloys than in the PM-HIP alloys. Notably, many peripheral grains in the wrought specimens are near yield even before load is applied. With increased loading, grain-scale stresses tend to homogenize in all specimens. Orientation fields measured using electron back scatter diffraction (EBSD) are used to determine grain morphologies and interpret the ff-HEDM data. The PM-HIP grains tend to be finer and rounder in shape than the wrought grains, potentially explaining the grain-scale stress distributions. Finally, yield strength and modulus of elasticity are measured for the four alloys and correlated to the resultant grain size and morphology from the fabrication processes.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering