Abstract
The reliability of titanium alloy welded joints is critical to the service safety of deep-sea engineering systems. The welding thermal cycle generates complex microstructures in Ti-6Al-4V, resulting in pronounced mechanical and electrochemical heterogeneity across joint regions. Herein, in-situ electrochemical testing was conducted to investigate stress corrosion cracking (SCC) behavior in distinct weld zones under hydrostatic pressure. Results reveal that hydrostatic pressure accelerates electrochemical reactions and enhances the SCC susceptibility—most severely in the heat-affected zone. This heightened vulnerability stems from the transformed β phase and lamellar secondary α phase, which promotes strain localization and impairs repassivation capability. This work presents the evidence of region-dependent-SCC susceptibility in Ti-6Al-4V welds under hydrostatic pressure, offering essential experimental insights for the safety assessment and welding optimization in deep-sea titanium structures.
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The data supporting the main findings are available in the manuscript and supplementary information file. Additional support can be obtained from the corresponding author upon reasonable request.
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Acknowledgements
This work was financially supported by the National Natural Science Foundation of China (U22A20111, U24A2030, 52501137) and the Opening Project of Key Laboratory of Advanced Marine Materials (2024K06).
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Y.C. (first author): wrote the original draft and maintained the equipment used in this work. R.L. (corresponding author): reviewed and edited the manuscript, conceptualization, and design of the experimental protocols. J.L. and S.D.: investigation, formal analysis, and wrote the original draft. W.W. and G.J.: signing experimental protocols. L.L. (corresponding author): designing experimental protocols. K.P. and F.W.: funding acquisition and provided research materials, samples, and instruments. All authors read and approved the final version.
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Professor Fuhui Wang is Associate Editor of npj Materials Degradation, but was not involved in the journal’s review of, or decisions related to, this manuscript. The remaining authors declare no competing financial or non-financial interests. The other authors do not have competing interests.
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Cui, Y., Liu, R., Liu, J. et al. Mechanistic investigation of hydrostatic pressure effects on stress corrosion cracking in Ti-6Al-4V welded joints. npj Mater Degrad (2026). https://doi.org/10.1038/s41529-026-00772-1
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DOI: https://doi.org/10.1038/s41529-026-00772-1
