Hydrogen Embrittlement of Rail Steels

Abstract

The resistance to hydrogen embrittlement (HE) of rail steels was studied. Hydrogen blistering, hydrogen-induced plasticity loss (HIPL) Iδ under slow strain rate test (SSRT), and hydrogen-induced cracking (HIC) under constant load were evaluated. Threshold hydrogen concentrations for blistering and HIPL were 0.7 ppm and 0.09 ppm for steel without vanadium (V), while they were 2.03 ppm and 0.26 ppm for the steel containing 0.09% V, respectively. HIPL (Iδ) was found to decrease linearly with the reciprocal of the diffusible hydrogen concentration (C0) (i.e., Iδ = 100 – 9/C0 for the steel without V, and Iδ = 105 – 27/C0 for steel containing V). This indicated that rail steel containing V is more tolerant to hydrogen than steel without V. The threshold stress for HIC (σc) decreased linearly with In C0 for steel containing V (i.e., σc [MPa] = 642 – 284 In C0 [ppm]).