Ultrasonic Defect Sizing in Grey Cast Iron Compared with Steel, Using the Maximum Echo Amplitude Technique

Abstract:In ultrasonic defect sizing using the maximum echo amplitude technique,the reflected echo signal height is taken to be related to the amount of ultrasoundpropagated energy which is reflected from defects and to the informationcontained in this reflected energy. In this investigation horizontal drilled holes ofknown sizes are considered in grey cast iron which is usually treated as the mostdifficult type of cast irons when ultrasonically inspected, due to its high soundattenuated nature. The defects sizing results obtained from grey cast iron arecompared with those obtained from a steel of a similar pearlitic matrix structure asa reference material. 2, 4, 6 & 8 mm drilled holes at known depths are prepared inboth grey cast iron and steel test samples. Maximum echo amplitude sizingmethod is adopted, using both compression wave probes & shear wave probes of1,2,4 & 6 MHz frequencies at different scanning positions. Although the resultsare only limited to defect sizing in grey cast iron with reference to steel, they do