Effect of Formic Acid on Corrosion Behavior of STBA24 Low-Alloyed Steel and Its Weldment in Simulated Boiler Water Containing Chloride Ions

Abstract

The effect of formic acid (HCOOH) in simulated boiler water containing chloride ions (Cl⁻) on the corrosion behavior of STBA24 low-alloyed steel and its weldment was investigated using electrochemical corrosion tests, immersion corrosion tests and surface analyses. The addition of 100 ppm HCOOH into water containing 100 ppm Cl⁻ resulted in thicker films with poor corrosion resistance that were formed easily on both the base metal and the weldment of STBA24, even though pit initiation was inhibited within a short time. The results suggest that the presence of 100 ppm formic acid in the simulated boiler water containing 100 ppm chloride ions promotes corrosion of the materials tested.

Fig. 7 Time variations of the OCPs of the specimens.