Detection of small internal fatigue cracks in Ti-6Al-4V by using synchrotron radiation μCT imaging

Abstract

The purpose of this study is to develop a method for detecting small internal fatigue cracks in Ti-6Al-4V by using synchrotron radiation provided at SPring-8. An electro-hydraulic fatigue testing machine was carried into the facility and a combination of uniaxial fatigue tests and micro computed tomography (μCT) imagings were conducted. The small specimen without size effect was newly designed for μCT imaging. The conditions of the fatigue tests were determined to observe internal crack initiations within the available time at the facility. To obtain a clear and accurate image of internal cracks, several important parameters for μCT imaging such as the crack opening load, the distance between detector and specimen, were optimized. As a result, multiple internal fatigue cracks sized around 30 μm or below were successfully detected.