Effects of surface grinding for scratched alloy 690TT tube in PWR nuclear power plant: Microstructure and stress corrosion cracking

Abstract

Alloy 690TT tube samples with different scratch depths were repaired by grinding treatments using abrasive papers of two different particle sizes. The microstructure and stress corrosion cracking (SCC) behavior were studied in detail. During grinding, the plastic accumulation zone vulnerable to SCC was removed. Meanwhile, some residual slip steps remained in the scratched area. Corrosion tests lasting 1000, 2000, 3000, and 4000 h show that the sensitivity and risk of SCC in the scratched area are decreased by grinding. Treatment using abrasive particles of a smaller size is more effective. Nevertheless, deep scratches remained hazardous even after the grinding.