Objective To address the corrosion failure of exhaust gas treatment equipment in high-temperature acidic flue gas environments, this study aims to reveal the corrosion mechanisms of three corrosive ions, Fe³⁺, Cl⁻, and \mathrmNO_3^- , in simulated flue gas condensate on S31254 steel, thereby providing technical support for engineering applications.

Method  Fe³⁺ (at mass concentrations of 50, 200, and 2000 mg/L), Cl⁻ (mass concentration 200 mg/L), and \mathrmNO_3^- (mass concentration 200 mg/L), were prepared. High-temperature immersion tests were conducted, and the morphology, composition, and elemental distribution of the corrosion products were systematically analyzed using scanning electron microscope, X-ray diffraction dnalysis, and energy dispersive spectrometer, with a focus on the effects of different ions on the corrosion behavior of the material.

Result The results indicate that Fe³⁺, Cl⁻, and \mathrmNO_3^- all significantly promote the corrosion of S31254 austenitic stainless steel. Among them, Fe³⁺ at a low mass concentration(50 mg/L), results in weight gain of the specimen, while at a high concentration (2000 mg/L), it intensifies corrosion, forming a continuous and thick corrosion product film. XRD analysis reveals the presence of Fe₂O₂CO₃ on the specimen surface. The presence of Cl⁻ increases the thickness of the corrosion product film and leads to the highest corrosion rate. In contrast, \mathrmNO_3^- promotes the formation of a thin but porous corrosion product film and induces pitting corrosion. EDS analysis shows significant loss of Fe and Ni, while Cr and Mo are enriched on the specimen surface.

Conclusion This study elucidates the influence of corrosive ions in the high-temperature acidic flue gas condensation environment. The findings provide a scientific basis for material selection, corrosion protection, and operation management of tail gas treatment equipment in natural gas purification plants, and also serve as a reference for subsequent related research.