Effect of Formic Acid on Pitting Corrosion of Steam Turbine Blade Material 13Cr Steel in Simulated Boiler Water Containing Chloride Ions

Abstract

The effect of formic acid (HCOOH) in simulated boiler water containing chloride ions (Cl⁻) on the pitting corrosion behavior of steam turbine blade material (13Cr steel) was investigated using electrochemical corrosion tests in addition to pit morphology analyses. Pit initiation was inhibited by the addition of 25–75 ppm HCOOH into the boiler water containing 100 ppm of Cl⁻ ions. Additions of 50 ppm and 75 ppm HCOOH into the boiler water containing 100 ppm of Cl⁻ both resulted in the formation of corrosion products as re-passivation films on the inner surfaces of the pits, which suppressed pit growth.