Experimental Methodology for Studying Strain Heterogeneity 5 with Microstructural Data from High Temperature Deformation

12 Abstract An experimental methodology has been developed 13 to study materials deformed at high temperatures using high 14 resolution ex situ digital image correlation (DIC). This study is 15 an advancement of techniques that have used sub-grain level 16 strain measurements and linked them to microstructural data 17 obtained with electron back-scatter diffraction (EBSD). The 18 approach utilized air blasting particles that were capable of 19 remaining unchanged onto a sample surface and loading the 20 sample at elevated temperatures in vacuum to prevent oxida21 tion. Two tensile experiments were performed at temperatures 22 of 700 and 800 °C on Haynes 230 (a nickel-based superalloy) 23 using DIC at high magnifications in order to study the hetero24 geneous strain fields. Overlaying the strain fields and micro25 structure data, areas of high strain were studied at a grain 26 boundary, triple junction of boundaries, and at a slip band. 27 The strain evolution at these areas was compared to the mean 28 strain accumulation. This study represents an advancement of 29 the usefulness of high resolution DIC by expanding the load30 ing conditions that can be studied and provided experimental 31 results to prove the feasibility.