Three-Dimensional In Situ Texture Development and Plasticity Accumulation in the Cyclic Loading of an alpha-Ti Alloy

High-energy synchrotron x-rays are used to track grain rotations and the micromechanical evolution of a hexagonal Ti-7Al microstructure as it is cyclically loaded below its macroscopic yield stress. The evolution of the grains through 200 cycles reveals a continual change in von Mises stress and orientation across the entire specimen indicating a slow accumulation of plasticity even though the sample was cycled below its macroscopic yield. Grain reorientation is consistent with the development of a tension texture despite the negligible magnitude of (macroscopic) plastic strain. It is observed that grains in a "hard" orientation (c-axis close to the loading direction) retain more residual stress on their slip systems upon unloading than the grains in a "soft" orientation.