The impact of temperature, chlorides and sulfate-reducing bacteria on the corrosion of steel in soil

This investigation aimed to study the corrosion performance of low-carbon steel in a soil environment at different temperatures. The steel specimens in the soil were treated at three temperatures: 5, 25 and 60 degrees C. The specimens were embedded in chloride-free soil for 21 days, and then 3.5% (by weight) sodium chloride (NaCl) was added to the soil. The specimens were then kept in the chloride-contaminated soil for 54 days. The results of electrochemical experiments showed superior corrosion performance of the specimens at 60 degrees C, which had the lowest corrosion activity, followed by the specimens at 5 and 25 degrees C. The slow nature of the kinetics of the corrosion reactions at 5 degrees C compared with that at ambient temperature was the reason for this improvement at 5 degrees C. The lower number of microorganisms, including sulfate-reducing bacteria, in the soil at 60 degrees C compared with that at the other temperatures was attributed to the lower corrosion activity of steel in the soil at 60 degrees C compared with the corrosion activity of steel in the soil at other temperatures.