Closed cracks can cause the underestimation or overlook by conventional (linear) ultrasonic method, because the ultrasound is transmitted through closed cracks. To solve this problem, we have developed an imaging method, subharmonic phased array for crack evaluation (SPACE), based on subharomonic generation by large-amplitude short-burst-wave input and phased-array imaging algorithm with frequency filtering. Thus far, we have demonstrated in the crack depth measurement in closed fatigue cracks and stress ...
英字タイトル:
Sizing of Closed Cracks Using Subharmonic Phased Array

It is well known that volumetric inspection by ultrasonic testing for cast austenitic stainless steel (CASS) piping, which is extensively used in primary loop of Japanese pressurized water reactors (PWR), is challenging due to unexpected beam skewing, dispersion and attenuation by its coarse and anisotropic crystal structures resulted from manufacturing process. The miss or false calling of the flaws and the deterioration of sizing performance are of great concerns in the ultrasonic testing for the ma...
英字タイトル:
Simulation of Ultrasonic Wave Propagation in Cast Austenitic Stainless Steel Piping

In this study, in order to propose a calibration method using a correction formula for each steel grade obtained in advance as a calibration method for plate thickness measurement using a permanent UT sensor such as MHI’s Thin-film UT sensor, a temperature-sound velocity correction formula for each steel grade was calculated by obtaining sound velocity values for each temperature from ordinary temperature to 200 degrees centigrade using the Thin-film UT sensor and multiple specimens of steel grade. Using th...
英字タイトル:
Proposal of calibration method for ultrasonic thickness continuous monitoring at high temperature using a thin film UT sensor