Stress corrosion cracking mechanisms in bridge cable steels: Anodic dissolution or hydrogen embrittlement

Abstract

Two key mechanisms, anodic dissolution, and hydrogen embrittlement, govern the stress corrosion cracking (SCC) in bridge cable steel wires. This study investigates the predominant mechanism influencing the SCC fracture time of bridge cable steel wires through electrochemical methods and thermal desorption analysis (TDA), offering protective measures. It contrasts the impacts of these mechanisms on electrochemical and mechanical properties and fracture morphology. The results show that the main mechanism of SCC in ammonium thiocyanate (NH4SCN) solution is hydrogen embrittlement (HE). Applying an anodic current (50 A/m2) can reduce the hydrogen absorption from 4.99 ppm to 0.2 ppm, and extend the fracture time from 26.1 h to 46.1 h. For the HE type SCC, the corrosion potential of the steel wire does not change with the corrosion time, and the tensile strength and diameter of the steel wire are the almost same as before corrosion. This research provides a theoretical basis for analyzing and protecting bridge cable steel wires against SCC.