PSI - Issue 59

Jesús Toribio et al. / Procedia Structural Integrity 59 (2024) 206–213 Jesús Toribio / Procedia Structural Integrity 00 ( 2024) 000 – 000

213

8

distribution. This also explains why the experimental scatter increases as the externally applied stress decreases and residual stress level becomes more important.

Fig. 4. Results at 35ºC (left) and 50º C (right) for different residual stress levels and boundaries of the experimental scatter areas (dashed lines).

6. Conclusions 1. Hydrogen embrittlement (HE) susceptibility of prestressing steels wires can be evaluated by the ATT, but the experimental scatter — measured in time to failure — is very high and it increases as the applied stress descends. 2. Computer modelling allows an analysis of the influence of residual stresses on the afore-said experimental scatter, on the basis of hydrogen transport by stress-assisted diffusion and taking into account residual stress laws. 3. Model predictions and experimental results agree fairly well, and tensile residual stresses shorten the wire life whereas compressive ones extend it. The role of residual stresses is more important at lower applied stress. References Astiz, M.A., 1986. An Incompatible Singular Elastic Element for Two- and Three- Dimensional Crack Problems. International Journal of Fracture 31, 105-124. Bergsma, F., Boon, J.W., Etienne, C.F., 1978. Détermination de la Sensibilité des Aciers Précontraints à la Fragilisation par l’Hydrogène. Revue de Métallurgie 75, 153-164. Brown, B.F., Fujii, C.T., Dahlberg, E.P., 1969. Methods for Studying the Solution Chemistry within Stress Corrosion Cracks. Journal of the Electrochemical Society 116, 218. Doig, P., Jones, G.T., 1977. A Model for the Initiation of Hydrogen Embrittlement Cracking at Notches in Gaseous Hydrogen Environments. Metallurgical Transactions 8A, 1993-1998. FIP-78, 1981. Stress Corrosion Test, Technical Report No. 5 FIP. Wexham Springs, Slough U.K. Hirth, J.P., 1980. Effects of Hydrogen on the Properties of Iron and Steel. Metalurgical Transactions 11A, 861-890. Ichiba, M., Sakai, J.I., Doshida, T., Takai, K., 2015. Corrosion Reaction and Hydrogen Absorption of Steel for Prestressed Concrete in a 20 Mass% Ammonium Thiocyanate Solution. Scripta Materialia 102, 59-62. Isecke, B., Mietz, J., 1993. The Risk of Hydrogen Embrittlement in High-Strength Prestressing Steels Under Cathodic Protection. Steel Research 64, 97-101. Iwanaga, K., Mizoguchi, S., Matsumoto, Y., Takai, K., Ichiba, M., 2022. Durability Evaluation of Surface Softened Steel Bar for Prestressed Concrete. Acta Polytechnica CTU Proceedings 33, 263-270. Takai, K., Seki, J. I., Yamaguchi, G., 1994. Hydrogen Occlusion Behavior of Si or Si, Ca Added High-Strength Steels with High Resistance to Delayed Fracture. Tetsu-to- Hagané 80, 1025-1030 . Takai, K., Seki, J.I., Homma, Y., 1995. Hydrogen Occlusion Behavior During Delayed Fracture in Cold Drawn Steel Wire and Heat Treated Steel Bar for Prestressed Concrete. Tetsu-to- Hagané 81, 243-248 . Toribio, J., 1997. Hydrogen Embrittlement of Prestressing Steels: The Concept of Effective Stress in Design. Materials & Design 18, 81-85. Toribio, J., 2000. Numerical Modelling of Hydrogen Embrittlement of Cylindrical Bars with Residual Stress Fields. The Journal of Strain Analysis for Engineering Design 35, 189-203. Toribio, J., Elices, M., 1991. Influence of Residual Stresses on Hydrogen Embrittlement Susceptibility of Prestressing Steels. International Journal of Solids and Structures 28, 791-803. Toribio, J., Kharin, V., 2006. Effect of Residual Stress-Strain Profiles on Hydrogen-Induced Fracture of Prestressing Steel Wires. Materials Science 42, 263-271. Vehovar, L., Kuhar, V., Vehovar, A., 1998. Hydrogen-Assisted Stress-Corrosion of Prestressing Wires in a Motorway Viaduct. Engineering Failure Analysis 5, 21-27.