Microstructure Characteristics and Corrosion Behavior of Low-Alloy High-Strength Steel used for Armor Layer under Exposure to H2S-Saturated Solution

The corrosion behavior of low-alloy steel exposed to saturated H2S solution is systematically studied using electron backscattered diffraction, scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and electron probe microanalysis. The experimental results suggest that the corrosion rate decreases with prolonged immersion time because more corrosion products are formed on the steel surface. The corrosion products consist of mackinawite, greigite, and molybdenite regardless of the corrosion time. The structure of the corrosion products transforms from a single layer into two layers with increasing corrosion time. The Cr content in the corrosion products is similar to that in the steel substrate. The corrosion products are rich in molybdenum owing to the formation of molybdenite.