ULTRASONIC FLAW DETECTING METHOD OF STEEL PIECE

摘要

PURPOSE:To make it possible to detect a short piping cavity in a steel piece by arranging slant angle probes having transmitting piezoelectric transducers and receiving piezoelectric transducers of phased arrays on the longitudinal direction of the steel piece for inclining a beam, changing the incident-angle bending degree, and engaging a flaw detecting gate on the vicinity of the center of the steel piece. CONSTITUTION:Slant probes 1 and 2 having a transmitting piezoelectric transducers and receiving transducers of a phased array are arranged in the longitudinal direction of a steel piece 3 for inclining a beam. The transmitting timing of the individual piezoelectric transducer is controlled for the transmitting piezoelectric transducers of a plurality of phased arrays which are provided in the probe 1. Thus, the incident angle thetaa of the transmitted echo is changed in a cyclic pattern in a short time period. A flaw detecting gate is engaged on the vicinity of the center of the steel piece 3. In this way, a piping cavity 4 enters in the gate, and the defect is judged. The reflected echo from the bottom surface is deviated from the gate and judged as a noise.