PSI - Issue 59

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000

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Procedia Structural Integrity 59 (2024) 82–89

© 2024 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 DMDP 2023 Organizers © 2024 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 DMDP 2023 Organizers Abstract Strain aging of structural steels is generally considered as an important factor in their embrittlement. In the laboratory, it is initiated by preliminary plastic deformation of a metal for the generation of dislocations, followed by short-term heating. In the study, a new hypothesis about the possibility of strain ageing occurring without any initial plastic deformation at the micro-scale under the presence of hydrogen in the process that induces internal stresses in steel was proposed. It was presumed that areas with local plastic deformation induced by hydrogen would be the preferred locations for steel to undergo strain aging during subsequent heating. This assumption was substantiated through experimental tests using the low-alloy pipe steel in different states (as-delivered state, after low-temperature tempering and after preliminary electrochemical hydrogen charging followed by low-temperature tempering). The mechanical properties of the steel, including strength, plasticity, impact strength, fracture toughness, and resistance to stress corrosion cracking, were assessed. Low-temperature tempering did not affect the mechanical behaviour of the steel. However, the steel subjected to the procedure of combining preliminary hydrogen charging with subsequent low-temperature tempering was characterized by a significant decrease in fracture toughness and resistance to stress corrosion cracking. Hydrogen had an impact on the embrittlement of the steel through the strain aging at local sites being preferable for hydrogen diffusion. © 2024 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 DMDP 2023 Organizers VII International Conference ―In -service Damage of Materials: Diagnostics and Prediction ‖ (DMDP 2023) Hydrogen role in strain aging of low alloy steels under operation Hryhoriy Nykyforchyn a *, Oleksandr Tsyrulnyk a , Oleh Venhryniuk a , Olha Zvirko a , Oleksandra Student a , Ihor Dzioba b , Dmytro Demianchuk a a Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5, Naukova St.; Lviv 79060, Ukraine b Kielce University of Technology, Av. 1000-an. of Polish State, 7; Kielce 25-314, Poland Abstract Strain aging of structural steels is generally considered as an important factor in their embrittlement. In the laboratory, it is initiated by preliminary plastic deformation of a metal for the generation of dislocations, followed by short-term heating. In the study, a new hypothesis about the possibility of strain ageing occurring without any initial plastic deformation at the micro-scale under the presence of hydrogen in the process that induces internal stresses in steel was proposed. It was presumed that areas with local plastic deformation induced by hydrogen would be the preferred locations for steel to undergo strain aging during subsequent heating. This assumption was substantiated through experimental tests using the low-alloy pipe steel in different states (as-delivered state, after low-temperature tempering and after preliminary electrochemical hydrogen charging followed by low-temperature tempering). The mechanical properties of the steel, including strength, plasticity, impact strength, fracture toughness, and resistance to stress corrosion cracking, were assessed. Low-temperature tempering did not affect the mechanical behaviour of the steel. However, the steel subjected to the procedure of combining preliminary hydrogen charging with subsequent low-temperature tempering was characterized by a significant decrease in fracture toughness and resistance to stress corrosion cracking. Hydrogen had an impact on the embrittlement of the steel through the strain aging at local sites being preferable for hydrogen diffusion. VII International Conference ―In -service Damage of Materials: Diagnostics and Prediction ‖ (DMDP 2023) Hydrogen role in strain aging of low alloy steels under operation Hryhoriy Nykyforchyn a *, Oleksandr Tsyrulnyk a , Oleh Venhryniuk a , Olha Zvirko a , Oleksandra Student a , Ihor Dzioba b , Dmytro Demianchuk a a Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5, Naukova St.; Lviv 79060, Ukraine b Kielce University of Technology, Av. 1000-an. of Polish State, 7; Kielce 25-314, Poland

Keywords: pipe steel, strain aging, hydrogen charging, residual stresses, embrittlement, fracture path. Keywords: pipe steel, strain aging, hydrogen charging, residual stresses, embrittlement, fracture path.

* Corresponding author. Tel.: +380 322 294213. E-mail address: hnykyforchyn@gmail.com * Corresponding author. Tel.: +380 322 294213. E-mail address: hnykyforchyn@gmail.com

2452-3216 © 2024 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 DMDP 2023 Organizers 2452-3216 © 2024 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 DMDP 2023 Organizers

2452-3216 © 2024 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 DMDP 2023 Organizers 10.1016/j.prostr.2024.04.013