Effect of Low Frequency Cyclic Stresses on Stress Corrosion Cracking of Duplex Stainless Steel 2205 in Chloride and White Liquor solutions

摘要

Low frequency cyclic stresses are experienced by the materials in a number of applications. Effect of low frequency cyclic stresses on stress corrosion cracking (SCC) of duplex stainless steel (DSS) 2205 was investigated in this study. Previous work has suggested that the two phases (austenite and ferrite) of DSSs have different residual stresses, and different SCC susceptibilities in acidic chloride and caustic white liquor (WL) environments. To understand the effect of low frequency fatigue on SCC initiation and propagation, tests were performed on the as-received DSS 2205 in two different environments where SCC could occur: 26 wt% NaCI at room temperature and WL at 170 °C. Test results on as-received material showed that cyclic stresses facilitate crack initiation. Intermetallic precipitates and austenite phase were the preferential sites for cracks to initiate in chloride and WL environments, respectively. The effects of fatigue parameters like stress ratio and maximum stress level of the cyclic stresses were also characterized.