Session: 19-02: Material Characterization by Ultrasonic waves

Paper Number: 97809

97809 - Ultrasonic Inspection of Rolled Microtextured Titanium Alloy 

Ultrasonic non-destructive evaluation (NDE) is a widely used defect detection and assessment tool in critical engineering components. Titanium alloys are one of the widely used materials in the aerospace industry, namely in critical rotating components of aircraft engines. These alloys are polycrystalline and are known to have complex microstructures. Titanium alloys investigated in this work comprise near-α rolled microstructure, large regions of primary α particles comprising similar orientation [0001] axes of the hexagonal close-packed unit cell, known as microtextured regions (MTRs) or macrozones. The propagation of ultrasonic waves in such complex polycrystalline materials is interrupted by the variations of microtextured regions (MTRs), which often makes the detection of flaws challenging to assess due to the ultrasonic signal fluctuations by scattering induced attenuation. This work investigates the impact of directional dependence of ultrasound on MTR. Electron backscatter diffraction (EBSD) investigations are performed to interrogate the MTR orientation. A finite element (FE) approach is implemented with a description of the MTR at the grain scale. The FE approach investigates the contribution of scattering induced attenuation of longitudinal waves in heterogeneous material, accounting for morphological, elastic, and crystallographic properties. The wave attenuation is numerically measured from the FE simulations at different MTR orientations and compared experimentally. The results indicate the strong dependence of ultrasonic attenuation on MTR orientation with respect to the wave propagation - higher attenuation along parallel MTR direction and lower in the normal direction. The intention is to quantify the ultrasonic attenuation for a given microstructure and perform the attenuation correction during the inspection to avoid false signals. This work also aimed at improving knowledge and the ability to predict the phenomenon of scattering induced attenuation.

Presenting Author: Abhishek Saini Nanyang Technological University Singapore