On the corrosion behaviour of novel high carbon rail steels in simulated cyclic wet–dry salt fog conditions

Eutectoid rail steels are prone to excessive corrosion in the coastal locations in India. In order to minimise this problem, four new rail steels with microalloying elements, Cu, Cr, Ni and Si were designed. The corrosion behaviour of these four rail steels were compared with the behaviour of three rail steels already in commercial application. Quantitative evaluation done by weight loss measurements after simulated wet–dry salt fog exposure test showed similar weight loss values for all rail steels. The FTIR spectra of rust samples revealed the presence of Fe3−xO4 as the major phase in both inner and outer layers of rusts on all the rail steels. Relative amounts of the different rust phases have been compared. SEM micrographs of the rusted samples revealed that the rust on Cr–Cu–Ni and Cr–Cu–Ni–Si rail steel was more compact than other rail steels. Impedance spectroscopy showed that the rust formed on Cr–Cu–Ni and Cr–Cu–Ni–Si rail steels resulted in the higher impedance in the high frequency region, compared to other rail steels.