Noncontact Ultrasonic Spectroscopy for Detecting Creep Damage in 2.25Cr-1Mo Steel

Abstract

Many of fossil power plants, which were constructed during 1960’s and 70’s and exceed more than 10,000 working hours, have presently been operating while they have been receiving progressive damage like creep as the time proceeds.^{1, 2} Furthermore, by shifting the base load of power from fossil power plants to nuclear power plants, they required the severe operating condition like daily or weekly start-up and shutdown in order to correspond to rapid change of the demand for power. As the consequence of the above trends, the degradation of materials in these plants was accelerated. Therefore, to safely operate plants, a technique for predicting the life and evaluate the damage of materials with nondestructive techniques is essential to assess the current state of these plants. Moreover, it is necessary for the technique to be simple and quick to apply to many objects.