Stress Redistribution During Dwell Fatigue in Ti‐6Al‐4V: In Situ Characterization and Crystal Plasticity Modeling

This study of dwell fatigue in titanium alloys utilizes characterization and DIC to map stress redistribution within domains of microstructure during stress dwell‐loading. The estimation of stresses is based on knowledge of measured strains during the stress hold and at the unloaded state such that spatially resolved creep and stress redistribution within hard and soft macrozones have been quantified. This provides the first spatially resolved experimental evidence of redistribution of stress during dwell onto grains that are badly orientated for slip. The experimental measurements observed are supported by CP simulations, which reproduce the magnitude and trend of local stress evolution across hard and soft grains. Additionally, the study quantifies the time constant associated with the redistribution in this Ti‐6Al‐4V alloy, and comparisons with other important Ti alloys are facilitated. The importance of cyclic progressive load shedding and the ratchet increase of hard domain stresses has also been demonstrated experimentally.