Improvements in or relating to methods and apparatus for ultrasonic flaw detection

摘要

868,258. Ultrasonic flow detection. ROLLSROYCE Ltd. Aug. 11, 1959 [Aug. 19, 1958], No. 26624/58. Class 40(7). In order to remove confusion caused by interface echoes in pulse ultrasonic testing of a specimen for flaws two adjacent transmitter-receiver probes 1, 2 are used and their electrical outputs are subtracted in difference amplifier A which feeds range-amplitude cathode-ray tube display C. As applied to turbine disc inspection the probes are moved radially as the blade rotates so as to scan it spirally.