PSI - Issue 21

Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 21 (2019) 166–172

© 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials organizers © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/ Peer-review under responsibility of the 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials organizers The main fractographic peculiarity for the operated steels comp ring to the steels in the initial state is th appe rance of delamination on the fr cture surfaces, w ich are oriented i th rolling direction. Correlation was ound for th t sted steels between ractograph c sings of their embrittlement due to operational degradation and their loss of brittle fracture resistance. It is concluded that a decrease of impact toughness caused by long term operation of pipeline steels is definitely concerned with the amount of delamination on t fracture surfaces. © 2019 The Autho s. Publ shed by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/ Peer-review under responsibility of the 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials organizers 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials Fractographic features of long term operated gas pipeline steels fracture under impact loading M. Hredil*, H. Krechkovska, O. Student, I. Kurnat Department of Diagnostics of Corrosion-Hydrogen Degradation of Materials, Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5 Naukova St., Lviv 79060, Ukraine Abstract Pipelines during their service life subjected to operational degradation, i.e. their mechanical characteristics worsened with time. Pronounced texture of pipe steels associated with their manufacturing process revealed itself in an essential difference in impact toughness determined for specimens cut in mutually perpendicular directions with respect to the pipe axis. Higher KCV values for longitudinal specimens as compared with transverse ones were explained by the difference in a length of perlite grain strips separated by ferrite grains in specimens of different orientation. A role of hydrogen, absorbed my metal during its operation, in steel degradation was discussed. The main fractographic peculiarity for the operated steels comparing to the steels in the initial state is the appearance of delamination on the fracture surfaces, which are oriented in the rolling direction. Correlation was found for the tested steels between fractographic sings of their embrittlement due to operational degradation and their loss of brittle fracture resistance. It is concluded that a decrease of impact toughness caused by long term operation of pipeline steels is definitely concerned with the amount of delamination on the fracture surfaces. 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials Fractographic features of long term operated as pipeline steels fracture under impact loading M. Hredil*, H. Krechkovska, O. Student, I. Kurnat Department of Diagnostics of Corrosion-Hydrogen Degradation of Materials, Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5 Naukova St., Lviv 79060, Ukraine Abstract Pipeli during th ir se vic l fe subjected to operational degrad tion, i.e. their mechanical c aracteristic wors ned with tim . Pron unce textur of pipe steels associated with th ir ma ufacturing proc ss revealed its lf in an essen ial diff rence in impact toughn ss det mined for specimens cut in mutually perpendicular dir ctions with respect to the pip xis. Hi her KCV values for ongitu inal specimens a compared with transverse ones were explained by the difference in a length of perlite grain strips separated by ferrite grains in specimens of different orientation. A role of hydrog n, absorb d my me l during its o eration, in st el degradati was disc ssed. Keywords: gas pipelines; impact toughness; fracture mechanisms; delamination.

Keywords: gas pipelines; impact toughness; fracture mechanisms; delamination.

* Corresponding author. Tel.: +380-99-19-39-062. E-mail address: mysya.lviv@gmail.com * Corresponding author. Tel.: +380-99-19-39-062. E mail address: mysya.lviv@gma l.com

2452-3216 © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/ Peer-review under responsibility of the 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials organizers 2452 3216 © 2019 Th Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/ Peer-review under responsibility of the 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials organizers

2452-3216 © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the 1st International Workshop on Plasticity, Damage and Fracture of Engineering Materials organizers 10.1016/j.prostr.2019.12.098