PSI - Issue 13

Ya. Khaburskyi et al. / Procedia Structural Integrity 13 (2018) 1651–1656 Author name / Structural Integrity Procedia 00 (2018) 000–000

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(2010, 2013), including crack growth resistance under long-term static loading in aggressive environments. Besides, in-service degraded steel has low fatigue crack growth resistance. Therefore, application of the proposed method for the crack arrest is especially actual. However in such cases a compromise should be found agreeing with not total but partial only crack closure, which would be still enough for crack arrest.

a b Fig. 5. Scheme of nominal and effective SIF in cycle of loading before ( a ) and after ( b ) crack treatment. Dash dot line indicates ineffective part of a loading cycle (crack closure effect). 4. Conclusions  The (electro)chemical method of fatigue crack arrest in steels by artificial crack closure creation due a falling the special liquid solution, what leads to a filling of crack cavity by solid products of the active solution components with crack surfaces metal interaction.  The proposed method of fatigue crack arrest is effective in all actual diapason of stress intensity factor Δ K range.  Implementation of the proposed method for long term operated steels could lead to of practically constant static stresses in the crack tip during cyclic loading, which should be taken into account in a view of the hazard of stress corrosion cracking and hydrogen embrittlement. References Elber, W., 1971. The significance of fatigue crack closure. ASTM STP 486, 230–242. Ritchie, R. O., Suresh, S., 1982. Some considerations on fatigue crack closure at near-threshold stress intensities due to fracture surface morphology. Metal. Trans. 5, 937–940. Suresh, S., Zamiski, G. F., Ritchie, R. O., 1981. Oxide-induced crack closure: an explanation for near threshold corrosion fatigue crack growth behavior. Metal. Trans. 8, 1435–1443. Никифорчин, Г.Н., Романив, О.Н., Андрусив, Б.Н., Здановский, В.Г., Василик, А.В., Чемеринский, Б.И., 1984. Авторское свидетельство СССР № 1125266 кл. С 21 D 7/02. Способ обработки изделий. Бюл. изобретений СССР № 43. (in Russian) Venhrynyuk, T. P., 2013. Fatigue crack retardation by the application of repair coatings to gas pipelines under pressure. Materials Science. 48, 6, 739–742 Romaniv, O. N., Nikiforchin, G. N., Andrusiv, B. N., 1983. Effect of crack closure and evaluation of the cyclic crack resistance of constructional alloys. Soviet Materials Science . 19, 3, 212–225. Nykyforchyn, H., Lunarska, E., Tsyrulnyk, O., et al., 2010. Environmentally assisted “in-bulk” steel degradation of long term service gas trunkline. Eng. Failure Analysis. 17, 624–632. Nykyforchyn, H., 2013. Environmentally Assisted Degradation of the Physical and Mechanical Properties of Long-Term Exploited Structural Steels. ESIS Newsletter. N52, 20-24. Nykyforchyn, H.M., Student, O.Z., Krechkovs’ka, H.V., Markov, A.D., 2010. Evaluation of the influence of shutdowns of a technological process on changes in the in-service state of the metal of main steam pipelines of thermal power plants. Materials Science. 46, 2. 177–189.