PSI - Issue 36

Available online at www.sciencedirect.com Available online at www.sciencedirect.com Sci nceDirect Structural Integrity Procedia 00 (2021) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2021) 000 – 000

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Procedia Structural Integrity 36 (2022) 334–341

© 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the conference Guest Editors Abstract The characteristics of strength, ductility and impact toughness of 17H1S steel in the initial state and after 31 years of operation on the main gas pipeline are analysed in terms of their sensitivity to degradation. It is shown that resistance to brittle fracture is the most sensitive of them to changes in the technical state of the metal. Ductile-brittle transition curves were plotted for both steel variants and fractographic features of specimen fracture at temperatures from +20 to –60 ° C. An increase in the temperature of ductile-brittle transition of steel from – 40 to – 30 ° C after its operation has been established. The ratio of the crystalline relief on the fractures of impact specimens is estimated. It has been established that the obtained data on the mechanical (brittle fracture resistance) and fractographic (fraction of the crystalline relief of the fracture) indicators correlate well with each other. In particular, with a decrease in the index of the mechanical state of the metal due to its operation, the fraction of the crystalline relief at the fracture increases. The data obtained from this study correlate with the previously obtained data for the steels of other gas pipelines. © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the conference Guest Editors Keywords: main gas pipe, degradation; fractographic features 1. Introduction Analysis of the causes of pipeline accidents indicates that more than half of them are caused by the combined effect of corrosive environments and operational loads (Ohaeri E. et al. (2018), Nykyforchyn 1 et al. (2016), Abstract The characteristics of strength, ductility and impact toughness of 17H1S steel in the initial state and after 31 years of operation on the main gas pipeline a analysed n terms of their sensitivity to degrada ion. It is shown that resistance to brittle racture is the most se sitive of them to ch ng s i the technical state of the metal. Ductile-brittle transi ion curves w re plo ed for both teel variants and fractographic fe tur s of specimen frac ur at emperatures from +20 to –60 ° C. An increas in th temperature of ductile-brittle transition of steel from – 40 to – 30 ° C after i s o tion has been es ablished. The ratio of the crystallin elief n the fractures of impact specimens is estimated. It has b en established that th obt ined data on the mechani al (br ttl fracture resist nce) and fractograph c (fraction of he crystallin r lief of the fracture) indicators c rrelate well with each other. In particular, with a decrease n the index mech n cal stat of the metal due to its operation, th fraction of the crystalline relief at the fracture increases. The data obtained from this study correlate with th previ usly obtained d ta f r the st els of other gas pipelines. © 2022 Th Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review u der responsibility of conference Guest Editors K ywords: main gas pipe, degradation; fractographic features 1. Introduction Analysis of the causes of pipeline accidents indicates that more than half of them are caused by the combined effect of corrosive environments and opera ional loads (Ohaeri E. et l. (2018), Nykyforchyn 1 et al. (2016), 1st Virtual International Conference “In service Damage of Materials: Diagnostics and Prediction” Influence of long-term operation of the 17H1S steel on the main gas pipeline on the change of the mechanical properties Halyna Krechkovska a,b, *, Volodymyr Kulyk b , Volodymyr Vira b , Oleksandra Student a a Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5, Naukova St., Lviv, 79060, Ukraine b Lviv Polytechnic National University, 12, Stepana Bandery St, Lviv, 79013, Ukraine 1st Virtual International Conference “In service Damage of Materials: Diagnostics and Prediction” Influence of long-term operation of the 17H1S steel on the main gas pipeline on the change of the mechanical properties Halyna Krechkovska a,b, *, Volodymyr Kulyk b , Volodymyr Vira b , Oleksandra Student a a Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5, Naukova St., Lviv, 79060, Ukraine b Lviv Polytechnic National University, 12, Stepana Bandery St, Lviv, 79013, Ukraine

* Corresponding author. Tel.: +380-67-81-12-543; E-mail address: krechkovskahalyna@gmail.com * Corresponding author. Tel.: +380-67-81-12-543; E-mail address: krechkovskahalyna@gmail.com

2452-3216 © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the conference Guest Editors 2452-3216 © 2022 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review u der responsibility of t conference Guest Editors

2452-3216 © 2022 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of the conference Guest Editors 10.1016/j.prostr.2022.01.043