Microstructure and hydrogen-induced stress corrosion cracking behaviour of U75V flash-welded joints in high-speed railways

The hydrogen-induced stress corrosion cracking (SCC) behaviour and mechanism of U75V welded joints (WJs) immersed in 3.5 wt% NaCl/hydrogenated solutions were investigated using slow strain rate tensile testing and electrochemical measurements. The WJs exhibited more negative potentials, higher corrosion current densities, slightly higher strength , and higher susceptibility to SCC in a hydrogenated solution than the base metal (BM). The strength and elongation of the WJs and BM significantly decreased after exposure to NaCl/hydrogenated solutions. These findings demonstrated that although U75V is extensively utilized in railway tracks, it is imperative to exercise corrosion protection measures for joints or employ specific corrosion-resistant rails in extreme applications to reduce service risks. • Hydrogen-induced stress corrosion cracking (SCC) of U75V weld joint was studied. • Electrochemical results, SCC propagation, and fracture surfaces were examined. • Weld joints had a higher corrosion rate and SCC tendency than the base metal. • The highest stress sensitivity was noted in the hydrogenated solution.