• cerium;
  • inclusions;
  • potentiostatic;
  • pitting corrosion;
  • spring steel

The effects of rare earth addition on the resistance to pitting corrosion of spring steel used in fasteners of high-speed railway were investigated by metallographic examination, potentiostatic polarization tests, and SEM–EDS analysis. The addition of Ce in spring steel resulted in the formation of rare earth oxides and oxy-sulfides and the decrease of the size and surface density of inclusions, which improved the resistance to pitting corrosion by decreasing the preferential interface areas for the initiation of the pitting corrosion. However, with increasing Ce content in steel, when up to 0.083%, the resistance to pitting corrosion was degraded dramatically due to the appearance of the large rare earth oxide inclusions. The optimal composition of Ce in the spring steel examined in this study is 0.053%.