Calibration method using a Pitch-Catch arrangement for ultrasonic inspection of acoustically noisy materials

摘要

A method for the ultrasonic inspection of acoustically "noisy" specimens, such as those having intrinsically coarse or variable grain structure (e.g., turbine rotor parts made of superalloy compositions), employs a "Pitch-Catch" analysis wherein a "through-transmitted" sound wave is first acquired for a plurality of reference locations on the specimen and used as a calibration standard to normalize ultrasonic inspection test data for that specimen prior to flaw/defect detection and processing. The through transmitted sound wave is also used for accurately equating the amplitude of "indications" (i.e., significant detected ultrasonic reflections)to that of a standardized theoretical reflector of known size (e.g., an equivalent "flat bottom hole" or EFBH reflector) so that the test sensitivity or "size of indications" can be uniquely determined for each specimen on which the test is performed.