Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : November 25, 2025 - November 29, 2025
In recent years, the demand for higher temperature and higher efficiency in high-temperature equipment such as jet engines and gas turbines has led to the research and development of heat-resistant steels and Ni-based superalloys, which have greatly improved heat resistance. Ti-Al alloys have been attracting attention as advanced heat-resistant materials for further improvement of efficiency and weight reduction. The microstructure of this alloy can be controlled by heat treatment, and the strength properties change accordingly. In this study, we elucidated the creep properties of a forged Ti-Al alloy Ti-43Al-5V-4Nb with a triplex microstructure. Therefore, nondestructive evaluation of such Ti-Al alloys was conducted to evaluate the damage and to predict the remaining life of these alloys when used at high temperatures. We investigated the evolutions of two nonlinear acoustic characterizations: resonant frequency shift and high harmonic components, with electromagnetic acoustic resonance (EMAR) throughout the creep life in the advanced heat-resistant Ti-Al alloy, Ti-43Al-5V-4Nb. EMAR is a contactless resonant method with an electromagnetic acoustic transducer (EMAT). This method enables not only to measure exact ultrasonic attenuation of sample but also to eliminate nonlinear acoustic effect between the sample and transducer. We used the axial SH wave EMAT, which transmits and receives axially polarized shear wave along a cylindrical surface of a circular rod for non-ferromagnetic materials. Two nonlinear ultrasonic properties and attenuation coefficients gradually decreases as creep advance. These changes can capture microstructural changes during creep.
