Ultrasonic characterization of intergranular stress corrosion cracking in austenitic stainless steel welds

Monitoring of Intergranular Stress Corrosion Cracking (IGSCC) initiation and growth by ultrasonic testing is carried out as per ASME Boiler & Pressure Vessel Code Sec. XI. The depth sizing is based on comparing signal amplitude from IGSCC with that from a reference notch. This approach results in undersizing of flaw because of roughness, branching etc. associated with IGSCC. limitation can be overcome by using known depths IGSCC as reference standard and/or employing ultrasonic sizing technique independent of signal amplitude. The paper describes limitations of conventional ultrasonic technique for IGSCC sizing, experiment to generate IGSCC of varying depths and results of IGSCC sizing using flaw tip diffraction technique.