Effects of Environmental Factors on Corrosion Behavior of U75V Steel for Metro Track

The effect of NaCl content, temperature and oxygen in the test solution on the corrosion behavior of U75V steel samples from failed track in a tunnel of Shanghai Metro was studied by immersion test and corrosion electrochemical test. The results showed that the corrosion rate of the steel decreased slowly with the increase of NaCl content in the range of 1.0%-10.0% and increased obviously with the increase of temperature in the solution exposed to air. Deaeration of the solution made the corrosion rate of the steel decreased significantly. The corrosion of U75V steel should be an activated polarization corrosion system controlled by the cathode process. In the solution environment exposed to air, the cathode underwent the oxygen depolarization process. Hydrogen depolarization process mainly occured after deaeration.