PSI - Issue 36

Hryhoriy Nykyforchyn et al. / Procedia Structural Integrity 36 (2022) 306–312 Hryhoriy Nykyforchyn, Leonid Unigovskyi, Olha Zvirko et al. / Structural Integrity Procedia 00 (2021) 000 – 000

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Fig. 4. Fracture peculiarities in the outlying zone of the fracture surfaces of specimens made of the as-received (a, c) and operated (b, d) steels without (a, b) and after (c, d) hydrogenation.

4. Summary The effect of long-term operation on the plasticity and hydrogen-induced cracking of the steel of the distribution pipeline was studied by tensing flat specimens with a thickness of 1.2 mm, cut out in the transverse direction to the pipe axis. Low-strength low-carbon steel operated for 52 years was characterised by a lower strength and plasticity compared to the as-received state, which indicated the degradation of the metal due to the intensive development of damage. Preliminary electrolytic hydrogenation of the specimens had almost no effect on the plasticity of the steel in the as-received state, however, significantly reduced it in the case of the operated metal. Microfractographic analysis of the hydrogenated tensile specimens revealed signs of low-energy fracture not only in the central zone of the fracture surfaces but also in their outlying areas. References Haeseldonckx, D., D’haeseleer, W. , 2007. The use of the natural-gas pipeline infrastructure for hydrogen transport in a changing market structure. International Journal of Hydrogen Energy 32(10 – 11), 1381 – 1386. Hredil, M., Tsyrulnyk, O., 2010. Inner corrosion as a factor of in-bulk steel degradation of transit gas pipelines, 18th European Conference on Fracture (ECF-18). Dresden, Germany, manuskript #483. Hredil, M.I., 2011. Role of disseminated damages in operational degradation of steels of the main gas conduits. Metallofizika i Noveishie Tekhnologii 33 (Spec. Iss.), 419 – 426.