Corrosion Behavior of Gray Cast Iron in Early Condensate Water Containing Acetic Acid

Weightlessness method, combined with scanning electron microscopy (SEM), energy spectroscopy (EDS) and X-ray diffraction (XRD), were used to study the corrosion behavior of gray cast iron used in low-pressure cylinders and separators of steam turbines in simulated early condensate water containing different content of acetic acid. The results show that gray cast iron corroded in the acetic acid-containing early condensate water, and the corrosion rate increased with the increase of the content of acetic acid,and chloride ion also had a great influence on corrosion. When the solution didn't contain Cl^-, there were fewer corrosion products on the surface of the gray cast iron, the surface was smooth and complete, and the degree of corrosion was light. The corrosion rate of gray cast iron in simulated initial condensate water containing 1.0 mg/L acetic acid was 0.045 mm/a, and the corrosion grade was grade 4. However, when 0.1 mg/L Cl^- was added to the solution, the corrosion rate of gray cast iron was about 0.07 mm/a, the corrosion level was grade five, and the surface was damaged and the corrosion was serious.