Development of methods for microtexture characterization and dwell fatigue life prediction of dual phase titanium alloys

icaf2023 Tracking Number 70

Near alpha and alpha plus beta titanium alloy can exhibit large reductions of dwell fatigue life. These reductions result from the formation of commonly oriented microscopic alpha-phase regions called microtexture (MTR). In this study, electron backscatter diffractions (EBSD), spatially resolved acoustic spectroscopy (SRAS) and ultrasonic testing have been used for characterization of MTR. The results of in-situ dwell fatigue test by digital image correlation (DIC) and the related quantitative fractography have been utilized to establish the role of MTR for dwell fatigue fracture. To develop a physical model to predict dwell fatigue life reduction depending on MTR, crystal plasticity analysis also has been conducted. This recently acquired information aims to be used to create a tool to estimate reduction of dwell fatigue life by non-destructive ultrasonic evaluation of titanium forgings, which will enable classification of materials from a MTR perspective and will support improvement of material quality in actual production. Results for Ti-64 will be presented here as it is a widely used alloy.