Effect of elastic compressive stress on passivation behavior and pitting corrosion mechanism of 2205 duplex stainless steel

Purpose 2205 DSS is widely used in refining, marine engineering, petrochemical and other industries. However, during service, 2205 DSS exhibits corrosion failure due to pitting corrosion. In service environments, 2205 DSS is frequently subjected to elastic stresses that significantly impact its pitting corrosion behavior. This study aims to investigate the effects of elastic compressive stress on passivation behavior and pitting corrosion mechanism of 2205 DSS. Design/methodology/approach Electrochemical impedance spectroscopy (EIS), Mott-Schottky (M-S) and X-ray photoelectron spectroscopy (XPS) tests are employed to analyze the corrosion resistance, defect density and chemical composition of the passive film, respectively. Cyclic potentiodynamic polarization is employed to analyze the pitting corrosion behavior of 2205 DSS. Pit growth is investigated by integrating the finite element simulations and scanning electron microscopy (SEM) observations. Findings The results reveal that the defect concentration decreases, and Cr2O3 content of the passive film increase under low compressive stress below 60% σ0.2, contributing to enhancement in the corrosion resistance. Conversely, under high compressive stress above 60% σ0.2, the thickness and compactness of passive film decrease, thereby increasing the pitting susceptibility of 2205 DSS. Most initial pits on 2205 DSS under elastic compressive stress occur at the austenite/ferrite boundary or in the austenite phase. Practical implications The finding that corrosion rates of DSS initially decrease at low compressive stresses due to the enhancement of the protective passive film, but increase above 60% yield strength, provides a clear stress threshold for component design. Industries can use this to avoid operating DSS parts in the high stress regime where corrosion accelerates, thereby minimizing unexpected failures and maintenance costs. Originality/value This study addresses the research gap regarding the influence of elastic compressive stress on the passive film properties and pitting corrosion mechanisms of 2205 DSS under varying pH conditions.