Ni基合金Alloy 617のクリープ損傷中の非線形超音波特性の変化

抄録

We studied evolutions of two nonlinear acoustic characterizations, resonant frequency shift and the higher harmonic components with electromagnetic acoustic resonance (EMAR) throughout the creep life in a Nickel based super-alloy, Alloy 617. EMAR was combination of the resonant acoustic technique with electromagnetic acoustic transducer (EMAT). We used axial shear-wave EMAT, which transmits and receives SH wave propagating in the circumferential direction of a cylindrical specimen. Creep tests were carried out at 973 K in air for a stress of 200MPa. In this test, we interrupted creep loading and furnace-cooled the samples. After measuring ultrasonic properties, we restarted the creep test. We repeated this procedure for every 200 hours until the rupture. Two nonlinear acoustic parameters monotonically increased as creep progress.