Issue 51

A. A. Lakhdari et alii, Frattura ed Integrità Strutturale, 51 (2020) 236-253; DOI: 10.3221/IGF-ESIS.51.19 252 C ONCLUSIONS 1. The study showed that the use of the finite element software ANSYS allows numerical simulations of the changes in the hydrogen concentration field and the stress-strain state of a hollow cylinder, not only the action of hydrogen at high pressure and temperature, as has been as done in the work [16], but also when hollow cylinder interacts with hydrogen at low temperature. 2. Adapted to the resolution of such problems, the ANSYS software package is used to model the behavior of different structures in a hydrogen-containing environment, taking into account the effects caused by both the influence of hydrogen on the mechanical properties of hydrogen material and stress state of structures, and considering the influence of state of stress on the kinetics of the interaction of hydrogen with structures. 3. The elaborate model of material behavior of structural elements in a hydrogenated medium takes into account the selective effect of low temperature hydrogen on the mechanical properties of materials. The selectivity is expressed as a function of the anisotropy induced by the hydrogen concentration and the rigidity of the stress state scheme. 4. The proposed model takes into account the influence of the type and the level of the stress state of the material on the kinetics of hydrogen penetration into the material by the dependence of the diffusion coefficient and the absorption limit of the material. hydrogen. 5.It should be noted that the established relationships fairly adequately describe the behavior of the tube under the combined action of charge and hydrogenation, while taking into account the destructive action of hydrogen. 6. The numerical simulation shows that the most dangerous case is the case of the simultaneous action of the charge and the hydrogen on the inner surface of the wall of the tube, because in this case the combination of the action of the stresses of traction and hydrogen leads to an intensive degradation of the tube material. 7.It should be noted that, contrary to the case of hydrogen at high pressure and temperature, the penetration of hydrogen occurs through the mechanism of activated diffusion and that the kinetics of hydrogen penetration depends on the rigidity of the scheme of the state of constraint. Since the state of stress changes with time under the influence of hydrogen entering the structure, the kinetics of hydrogen penetration into the structural element also changes over time. 8. Hydrogen embrittlement of metal structures is closely related to their microstructure, and in particular to the processes of segregation and diffusion occurring at interfaces and defects. R EFERENCES [1] Lynch, S. (2019). Discussion of some recent literature on hydrogen-embrittlement mechanisms: addressing common misunderstandings, Corrosion Reviews; 37(5), pp. 377-395. DOI: 10.1515/corrrev-2019-0017. [2] Djukic, M.B., Bakic, G.M., Sijacki Zeravcic, V., Sedmak, A., Rajicic, B. (2016). Hydrogen Embrittlement of Industrial Components: Prediction, Prevention, and Models, Corrosion; 72 (7), pp. 943-961. DOI: 10.5006/1958. [3] Bueno, A., Moreira, E., Gomes, J. (2014). Evaluation of stress corrosion cracking and hydrogen embrittlement in an API grade steel, Engineering Failure Analysis; 36, pp. 423–431. DOI: 10.1016/j.engfailanal.2013.11.012. [4] Serebrinsky, S., Carter, E.A., Ortiza, M. (2004). A quantum mechanically informed continuum model of hydrogen embrittlement, J. of the Mechanics and Physics of Solids; 52 (10), pp. 2403 – 2430. DOI: 10.1016/j.jmps.2004.02.010. [5] Kolachev, B.A. (1999). Hydrogen in metals and alloys, Metal Science and Heat Treatment; 41(3), pp. 93-100. DOI: 10.1007/BF02467692. [6] Woodtli, J., Kieselbach, R. (2000). Damage due to hydrogen embrittlement and stress corrosion cracking, Eng. Failure Analysis; 7, pp. 427- 450. DOI: 10.1016/S1350-6307(99)00033-3. [7] Lynch, S. (2012). Hydrogen embrittlement phenomena and mechanisms, Corrosion Reviews; 30(3-4), pp. 105–123. DOI: 10.1515/corrrev-2012-0502. [8] May, L.M., Dadfarnia, M., Nagao, A., Wang, S., Sofronis, P. (2019). Enumeration of the hydrogen-enhanced localized plasticity mechanism for hydrogen embrittlement in structural materials, Acta Materialia; 165, pp. 734-750. DOI: doi.org/10.1016/j.actamat.2018.12.014. [9] Djukic, M.B., Bakic, G.M., Zeravcic, V. S., Sedmak, A., Rajicic, B. (2019). The synergistic action and interplay of hydrogen embrittlement mechanisms in steels and iron: Localized plasticity and decohesion, Eng. Fracture Mechanics; 216, pp. 106-528. DOI: 10.1016/j.engfracmech.2019.106528.