Hydrogen embrittlement of microalloyed rail steels

The effect of hydrogen on mechanical properties of three different rail steels of composition in weight percent, C–Mn (0.71C–1.04Mn), Cu–Mo (0.69C–1.16Mn–0.24Cu–0.18Mo) and Cr–Cu–Ni (named as NCC) (0.71C–1.15Mn–0.59Cr–0.40Cu–0.20Ni) was studied. Hydrogen was charged electrochemically in 0.5 mol l−1 H2SO4 solution at a current density of 0.1 A cm−2 for 12 h. Duplicate tensile tests were performed before and after hydrogen charging. The tests revealed that the rail steels were susceptible to hydrogen embrittlement as confirmed by the reduction in ductility. The degree of embrittlement was higher in C–Mn rail steel compared to the Cu–Mo and NCC rail steels. The hydrogen-charged samples revealed brittle features after hydrogen charging.