Characterisation of rust on microalloyed rail steel exposed to coastal location in India

Abstract

The rusts on the gauge face and non-gauge face of two rail steels (traditional C–Mn and novel Cu–Mo rail steel) were characterised after two years of service to corelate with an apparent visual observation of a lower corrosion rate in the case of the Cu–Mo rails. Rust samples were characterised by X-ray diffraction, Fourier transform infrared spectroscopy and Mössbauer spectroscopy. X-ray diffraction patterns showed diffuse peaks indicating poorly crystallised rust phases, while the phases identified by the other techniques were γ-FeOOH (lepidocrocite), α-FeOOH (goethite), Fe_3–xO₄ (magnetite), δ-FeOOH and α-Fe₂O₃ (haematite). The enhanced corrosion of the gauge face compared to non-gauge face for both rails and that of C–Mn rails compared to Cu–Mo rails was related to the higher amount of γ-FeOOH and lower amount of Fe_3–xO₄.