Host: The Japan Society of Mechanical Engineers
Name : [in Japanese]
Date : September 13, 2020 - September 16, 2020
The effective lifetime of Ni-base alloy decreased drastically by the frequent change of the output of power plants to assure the stable power supply with various renewable energies. The conventional linear damage rule, however, can no longer explain the accelerated damage of Ni-base alloy under creep-fatigue loading. The main reason for the accelerated damage was the change of fracture mode from transgranular to intergranular. It was also found that the initial intergranular cracking under creep-fatigue loading always appeared at certain grain boundaries. Therefore, in this study, intermittent creep-fatigue test was applied to these two Ni-based alloys at 750oC and the change of their micro texture was continuously monitored by using FE-SEM (Field Emission-Scanning Electron Microscope) and EBSD (Electron Backscattered Diffraction) analysis. Eventually, two completely different degradation modes were found in the two Nick-based alloys, due to their different microstructure.
