| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems in a conventional flaw detection method for performing a flaw detection from four side surfaces of a square billet that the equipment cost is increased because of the necessity of a number of probes, and it is difficult to keep the precision of the probes and tracking mechanism part provided on the two lower side surfaces for a long period. SOLUTION: In this ultrasonic flaw detecting method and device, the inner part of the square billet K is flaw-detected by use of vertical probe groups a and b, and the surface and subcuticular blind band h of the square billet K which is not flaw- detectable by this flaw detection is flaw-detected by use of a surface wave probe, and the blind bands n1, n2, n3 and n4 of the square part subcuticular inner part of the square billet K which is not flaw-detectable by this flaw detection and the flaw detection by the vertical probe groups a and b are detected by use of vertical wave oblique probes, and these flaw detections are performed from two adjacent side surfaces of the longitudinally carried square billet. Accordingly, since the flaw detection can be performed from the two adjacent side surfaces of the square billet, the set of a number of probes can be dispensed with to reduce the equipment cost. Since the probes and tracking mechanism part are provided only on the upper side surfaces, the precision can be kept for a long period.
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