Study on Hydrogen-Induced Delayed Fracture Behavior of Ultra-high Strength Marine Mooring Chain Steel

S. J. Li*, Z. Y. Wei, M.Y. He, S. L. Su, P. Zhu, D. H. Ping Y. Tian

School of Chemical Engineering, Zhengzhou University, 100 Science Avenue, Zhengzhou, 450001, P. R. China

EXTENDED ABSTRACT: The development of marine engineering to deep sea puts forward higher requirements for the lightweight of offshore platform. As the main equipment of offshore platform, mooring chain has high strength and high reliability, which is an important target of platform lightweight construction, and thus promotes the research and development of high-strength mooring chain steel. It’s found that the increased strength of mooring chain steel will significantly improve its hydrogen-induced delayed fracture, which limits the wide application of high-strength mooring chain steel in the field of marine equipment. In this study, to investigate the hydrogen-induced delayed fracture behavior of high-strength mooring chain steel, the quantitative analysis of hydrogen content by hydrogen thermal desorption would be studied. The relationship between hydrogen content and fracture stress would be established. The distribution of hydrogen over time and the activation energy of hydrogen trap site in mooring chain steel would be studied. The hydrogen diffusion coefficient and the hydrogen trap sites are determined, which reveals the fracture mechanical behavior of mooring chain steel and clarifies the microscopic mechanism of delayed fracture of mooring chain steel. This research is expected to deepen the research on hydrogen-induced delayed fracture of high-strength mooring chain steel, and lay a foundation for the design and development of high-strength mooring chain steel and its application in offshore platform lightweight.