Effect of vanadium on stress corrosion cracking for high-strength railway steel in simulated SO2-polluted environment

Abstract

Railway steel plays critical role in railway tracks, which influences the safety of this system. In this work, the effect of vanadium on the SCC under anodic dissolution (AD) and hydrogen embrittlement (HE) mode of railway steel is investigated. A high-strength railway steel is alloyed with 0.08 wt % vanadium and compared with the original steel. The results indicate that adding V reduces the galvanic effect between phases in the railway steel, then decreases the general corrosion rate, and retards the formation of localized corrosion, which is the crack source. Therefore, V reduces the AD-SCC risk from the elongation loss of railway steel from 69.6 % to 44.5 % under open circuit potential (OCP) conditions. Additionally, V refines the interlamellar spacing of pearlite, resulting in a longer length between ferrite and cementite, which is a hydrogen storage site. Therefore, the elongation loss at a hydrogen evolution potential is 82.6 % for the railway steel containing V, which is 5.4 % lower than steel without V, indicating V improve the HE-SCC resistance. Overall, V exhibits a reduced risk of AD-SCC, characterized by a lower likelihood of localized corrosion initiation and slower corrosion propagation rates. Furthermore, it offers an increased number of hydrogen trap sites, which help prevent the accumulation of high hydrogen concentrations within the material, ultimately enhancing its resistance to HE-SCC.