Short-term corrosion behavior of Q235 steel and X70 pipeline steel in gray desert soil in North America

The short-term corrosion behavior of Q235 and X70 steel samples buried for one year in the test trench in a typical mountain sierozem area in Calgary, Canada was investigated by corrosion rate measurement, corrosion characteristic observation and analysis through scanning electrochemistry microscopy and X-ray diffraction, and soil physical and chemical properties analysis. It is found that Q235 steel has a close average corrosion rate and maximum pitting corrosion depth to X70 pipeline steel, but the former has an obviously higher pitting density than the latter. The corrosion products of these two metals are similar and mainly composed of FeOOH, Fe₂O₃ and Fe₃O₄, and the corrosion product layer is loose with cracks and not able to prevent these metals from corrosion. There are multiplex bacteria, such as sulphate reduction bacteria (SRB), sulphate oxidation bacteria (SOB) and heterotrophic bacteria in the soil attaching to the two steel samples, which are in cooperation to accelerate the occurrence of localized corrosion under the corrosion product layer due to the effects of their metabolic actions on corrosion processes.