Ultrasonic flaw-detection method and apparatus for blade groove in turbine rotor disc

A method of performing ultrasonic flaw-detection for a blade groove portion of a turbine rotor disc for checking a blade groove portion by a phased array method, the blade groove portion being disposed on a rotor disc of a turbine for fixing a turbine blade, the method of performing ultrasonic flaw-detection comprising:

• an arrangement step of arranging a phased array probe including a plurality of oscillators each of which is capable of emitting ultrasonic waves on an end surface of the rotor disc, in a parallel state in which the plurality of oscillators are arranged along a circumferential direction of the rotor disc;
• a first transmission step of emitting ultrasonic waves from the plurality of oscillators in the parallel state, while a timing of emitting the ultrasonic waves from each of the oscillators is controlled in a first emission pattern, and receiving reflection waves of the ultrasonic waves;
• and
• a second transmission step of emitting ultrasonic waves from the plurality of oscillators in the parallel state, while the timing of emitting the ultrasonic waves from each of the oscillators is controlled in a second emission pattern different from the first emission pattern, and receiving reflection waves of the ultrasonic waves,
• wherein the blade groove portion for fixing the turbine blade disposed on the rotor disc of the turbine extends in an arc shape so as to deviate from an axial direction of the rotor disc.