|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Fatigue in Materials: Fundamentals, Multiscale Modeling and Prevention
||Micromechanics of Biaxial Cold Dwell Fatigue Mechanisms in Ti-7Al Elucidated Using Far-field High-energy Diffraction Microscopy
||Aaron Stebner, Garrison Hommer, Adam Pilchak
|On-Site Speaker (Planned)
Alpha-titanium alloys have limited plasticity mechanisms due to hexagonal close-packed (HCP) crystal structure, and also twinning deformation, observed in many HCP alloys, is suppressed by adequate aluminum content. Critically resolved shear stress anisotropy between remaining slip systems gives rise to soft grains preferentially oriented for slip, and hard grains that are not. Dwell fatigue is known to adversely affect life compared to regular cyclic fatigue for uniaxial loading in Ti-7Al. It is generally postulated that this dwell debit is due to load shedding between soft and hard grains that occurs because of low hardening and propensity to creep at low temperatures. However, biaxial dwell fatigue life and mechanisms still lack understanding as evidenced by a persisting inability to accurately model fatigue lives of aircraft turbine compressor blades. We present new micromechanical mechanistic insights gained by studying tension-tension dwell fatigue in-situ using far-field high-energy diffraction microscopy.
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