Comprehending the coupled effect of dissolved oxygen and yield strength on passive film features of duplex stainless steel

This study measures the combined effects of elastic stress (0–90%σs) and dissolved oxygen (0∼20 mg/L) on the passive film of 2205 duplex stainless steel in high-chloride conditions (150,000 mg/L Cl−, 90°C). The findings indicate that with 90%σs and 20 mg/L DO, the film growth rate peaks at 301% enhancement (0.152→0.609 nm/log t). Stress decreases the Cr/Fe ratio (1.08→0.52), indicating Fe dissolution, and increases donor density (4.30×1019→2.02×1024 cm−3). At 80%σs and 10 mg/L DO, critical thresholds are found, beyond which film destabilization takes place. In order to avoid defect-rich films (ND>1022cm−3) and premature failure, industrial applications should maintain DO≤10mg/L and stress≤80%σs.