Ultrasonic Measurement of Closed Stress Corrosion Crack Depth Using Subharmonic Phased Array

Abstract

We formed a stress corrosion crack (SCC) more than 10 mm deep to simulate those generated in atomic power plants. We precisely imaged the formed SCC by a novel imaging method, namely, the subharmonic phased array for crack evaluation (SPACE), and found that it had complex branches. Subsequently, we cut the specimen for the optical observation of the cross sections, and discussed the origin of the SCC extension on the basis of the optical microscopic observation of the cross sections. To examine the open and closed parts of crack in the optical images, we superposed the crack extracted from the optical images onto the SPACE images. We compared the optically and SPACE-measured crack depths, and demonstrated that SPACE is useful in reducing the underestimation of closed-crack depths.

Characterizing stress corrosion cracking in stainless steel using nonlinear resonant ultrasound spectroscopy

“…Ohara et al developed the Subharmonic Phased Array for the detection of SCC on the opposing surface of a metal sample and on the same side as the array using surface acoustic waves. 13,14 Dynamic Acousto-Elastic Testing is a low frequency pump and higher frequency probe technique that was used by Rivière et al to extract and additional nonlinear parameters. 15 Ohara et al used NRUS to locate SCC by analyzing the measured from a couple different resonance modes based on whether the mode had a strain node or antinode at the location of the SCC.…”

A study of bolt fastening evaluation using second harmonic ultrasonic pulse waves

“…Recently, the measurement of nonlinear ultrasonic waves, including second harmonic components, has been applied for nondestructive evaluation [5][6][7][8][9][10][11][12]. The second harmonic components are generated by the nonlinear response of plastic deformation, dislocations, closed cracks or the contact acoustic nonlinearity (CAN) [10,13,14].…”

A Novel Double-Layered Piezoelectric Transducer for Detecting Second Harmonic Ultrasonic Pulse Waves

“…However, dislocation, closed cracks and plastic deformation cannot be easily detected by a conventional pulse-echo method. Recently, second harmonic ultrasonic waves have been studied as new tools for testing materials [1][2][3][4][5][6]. Second harmonic ultrasonic waves are generated by nonlinear vibrations of dislocation and closed cracks has been considered as the resonance with finiteamplitude ultrasonic waves traveling through the testing materials.…”