Corrosion behaviour of tube pile steel produced by thermo-mechanical controlled processing (TMCP) technology with Cr addition ranging from 0.5 to 2.0 wt% in half-immersion environment were investigated. Results indicated that the most serious corrosion occurred in the liquid–air interface zone and the corrosion type transformed from pitting corrosion to uniform corrosion gradually with the increasing addition of Cr. Increasing addition of Cr reduced the pit depth of steel, but did not decrease the overall corrosion rate of steel during the 5 months’ half-immersion corrosion due to the microstructure transformation with the increase of Cr content.