Slow strain rate stress corrosion testing at elevated temperatures and high pressures

Slow strain rate stress corrosion cracking experiments have been performed on single phase and duplex phase 304 stainless steels at 290°C. Environmental variables included chloride concentrations (0–1000 ppm), oxygen concentration (0–2 ppm) and potential (?_corr to + 500 mV vs Ag/AgCl). These experiments have shown that s.c.c. resistance is relatively unaffected by Cl^? if O₂ concentrations approach zero. However, at 2 ppm O₂ concentration, there is a large decrease in resistance with increasing Cl^? concentrations. Anodic polarization of the steels during straining in solutions containing 100 ppm Cl^? and 0 ppm O₂ showed a threshold potential for s.c.c. at ～ 500 mV more noble than the corrosion potential (? 650 ± 60 mV vs Ag/AgCl at temperature).