抄録
The novel imaging method, subharmonic phased array for crack evaluation (SPACE) is a practical solution for imaging closed cracks. SPACE uses a LiNbO3 transmitter and array receiver based on the subharmonic waves and phased array. In this paper, we developed SPACE with a single array transducer applicable to small objects. We imaged a stress corrosion crack (SCC) in a heat affected zone (HAZ) of type 304 stainless steel specimen, formed in high temperature pressurized water to simulate the actual cracks formed in nuclear power plants. As a result, we succeeded in visualizing the closed crack tip in the subharmonic image with high selectivity, although the specimen led to strong linear scattering at the grain boundaries. This result will significantly contribute to improving the safety and reliability of nuclear power plants.
