Abstract: The welding quality of cast austenitic stainless steel (CASS) pipeline welds is critical to nuclear reactors. The mandatory requirements of NDT have been raised in inspection code of nuclear power plant, which is about the welding quality and service condition of CASS welds. However, the complex structure of welds makes the ultrasonic testing of CASS welds challenging. Phased array ultrasonic testing (PAUT) technique is promising to solve this problem. The difficulties of PAUT for thick wall CASS pipeline welds are analyzed, the corresponding key issues and solving strategies are summarized. Furthermore, the research progress and latest research results at home and abroad are described, which provides reference for the PAUT of thick wall CASS pipeline welds.

Key words: Cast austenitic stainless steel(CASS), Phased array ultrasonic testing(PAUT), Thick wall, Weld