Corrosion Behavior of Low Alloy Steels in High-mineralized MineWater postprint

Abstract: The corrosion behavior of low alloy steels, such as 27SiMn, 30CrMnSi, 30CrMnTi, 40Cr and Q550 was studied comparatively in high-mineralized coal mine water, tap water and NaCl solution by means of immersion test, salt spray test and electrochemical methods as well as XRD and SEM with EDS. The results showed that elements Cr and Si can significantly affect the corrosion resistance of low alloy steels: in chloride containing media, Si exhibits stronger effect than Cr on the corrosion; whereas in the presence of oxygen (water and gas phase), Cr exhibits stronger effect than Si. Therefore, 30CrMnTi and 40Cr have better corrosion resistance in the coal mine water. The corrosion behavior of the low alloy steels in the coal mine water depend not only on the role of alloying elements but also on the compactness of the formed limescale induced by mineral ions. The limescale, on one hand, can fill the porous rust layer, which slows down the corrosion rate of the steel, however, on the other hand, due to the low concentration of oxygen at the zone below the limescale, where the corrosion of the steel can be accelerated. Finally the corrosivity of three corrosive media can be ranked as the order from severe to mild: 3.5%NaCl solution, high mineralized mine water and tap water.