Electrochemical insights into the High-Temperature corrosion mechanism of 12Cr1MoV steel under Chlorine-Rich conditions

Abstract

In waste-to-energy boilers, heat-transfer surfaces are typically exposed to chloride-rich deposits, resulting in severe corrosion and tube failure. Online corrosion monitoring is vital for understanding and mitigating such degradation. This study examines the high-temperature corrosion behavior of 12Cr1MoV steel under chlorine-rich fly ash deposits at 550 °C, 650 °C, and 800 °C. Corrosion rates were evaluated using both the weight loss method and an online electrochemical monitoring technique. Results indicate that chlorine-induced corrosion intensifies with increasing temperature, mainly due to enhanced chlorine diffusion. The oxide scale evolves from a thin, irregular layer at lower temperatures to a multi-layered structure at 800 °C, where a ∼ 1 μm scale comprising an Fe-rich outer layer and a Cr-enriched inner layer was observed. However, the chromium content was insufficient to form a continuous protective scale. The electrochemical method, based on linear polarization resistance (LPR), provided online corrosion data that correlated well with the weight loss method at 550 °C and 650 °C. At 800 °C, deviations occurred due to thick oxide formation affecting the electrochemical response. These findings clarify the corrosion mechanism of 12Cr1MoV steel in high-chlorine atmospheres and confirm the feasibility of using online electrochemical monitoring to capture corrosion dynamics. This approach enables early detection of accelerated corrosion, offering practical benefits for boiler material assessment and maintenance in waste-to-energy environments.