Abstract
Turbine generator in power plants is an important equipment, and requires its preventive maintenance for normal operation.For the inspection efficiency for turbine generator rotor, the application of ultrasonic testing technique for the keyway in a rotor shaft is demanded. The ultrasonic testing for the keyway in a rotor shaft detects crackings occurred diagonally for rotor axis. For this issue, the authors developed the cracking detection techniques by the phased array ultrasonic testing method using an array probe installed in the distant position from the keyway. The ultrasonic beams propagate three-dimensionally because the rotor shaft is a column. Therefore a control of the beam incident direction is difficult. Therefore the ultrasonic beam angle and the ultrasonic probe position for cracking detection were calculated based on the rotor's geometry. The authors confirmed the possibility of crackings detection in this calculated condition by the experiment using electric discharge machining slit in the specimen simulated a rotor shaft, and ensured the inspection reliability.
