Effect of Hydrogen on Tensile Properties and Fracture Behavior of Two High-Strength American Petroleum Institute Linepipe Steels

This study explored the influence of hydrogen on the tensile properties and fracture behavior of high-strength API X70 and X80 linepipe steels with bainitic microstructures under varying hydrogen charging conditions. The X70 steel exhibited a ferritic microstructure with some pearlite, while the X80...

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Main Authors: Dong-Kyu Oh, Min-Seop Jeong, Seung-Hyeok Shin, Byoungchul Hwang
Format: Article
Language:English
Published: MDPI AG 2024-12-01
Series:Metals
Subjects:
Online Access:https://www.mdpi.com/2075-4701/14/12/1397
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author Dong-Kyu Oh
Min-Seop Jeong
Seung-Hyeok Shin
Byoungchul Hwang
author_facet Dong-Kyu Oh
Min-Seop Jeong
Seung-Hyeok Shin
Byoungchul Hwang
author_sort Dong-Kyu Oh
collection DOAJ
description This study explored the influence of hydrogen on the tensile properties and fracture behavior of high-strength API X70 and X80 linepipe steels with bainitic microstructures under varying hydrogen charging conditions. The X70 steel exhibited a ferritic microstructure with some pearlite, while the X80 steel showed a bainitic microstructure and fine pearlite due to the addition of molybdenum. Slow strain rate tests (SSRTs) were conducted using both electrochemical ex situ and in situ hydrogen charging methods subjected to different current densities. The SSRT results showed that in situ hydrogen-charged SSRT, performed at current densities above 1 A/m<sup>2</sup>, led to more pronounced hydrogen embrittlement compared to ex situ hydrogen-charged SSRT. This occurred because hydrogen was continuously supplied during deformation, exceeding the critical concentration even in the center regions, leading to quasi-cleavage fractures marked by localized cleavage and tearing ridges. Thermal desorption analysis (TDA) confirmed that a greater amount of hydrogen was trapped at dislocations during in situ hydrogen-charged SSRT, intensifying hydrogen embrittlement, even with a shorter hydrogen charging duration. These findings highlight the importance of selecting appropriate hydrogen charging methods and understanding the hydrogen embrittlement behavior of linepipe steels.
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spelling doaj-art-050b03dc7ca84a3498347245b06f12e22025-08-20T02:57:16ZengMDPI AGMetals2075-47012024-12-011412139710.3390/met14121397Effect of Hydrogen on Tensile Properties and Fracture Behavior of Two High-Strength American Petroleum Institute Linepipe SteelsDong-Kyu Oh0Min-Seop Jeong1Seung-Hyeok Shin2Byoungchul Hwang3Department of Materials Science and Engineering, Seoul National University of Science and Technology (SEOULTECH), 232 Gongneung-ro, Nowon-gu, Seoul 01811, Republic of KoreaDepartment of Materials Science and Engineering, Seoul National University of Science and Technology (SEOULTECH), 232 Gongneung-ro, Nowon-gu, Seoul 01811, Republic of KoreaDepartment of Materials Science and Engineering, Seoul National University of Science and Technology (SEOULTECH), 232 Gongneung-ro, Nowon-gu, Seoul 01811, Republic of KoreaDepartment of Materials Science and Engineering, Seoul National University of Science and Technology (SEOULTECH), 232 Gongneung-ro, Nowon-gu, Seoul 01811, Republic of KoreaThis study explored the influence of hydrogen on the tensile properties and fracture behavior of high-strength API X70 and X80 linepipe steels with bainitic microstructures under varying hydrogen charging conditions. The X70 steel exhibited a ferritic microstructure with some pearlite, while the X80 steel showed a bainitic microstructure and fine pearlite due to the addition of molybdenum. Slow strain rate tests (SSRTs) were conducted using both electrochemical ex situ and in situ hydrogen charging methods subjected to different current densities. The SSRT results showed that in situ hydrogen-charged SSRT, performed at current densities above 1 A/m<sup>2</sup>, led to more pronounced hydrogen embrittlement compared to ex situ hydrogen-charged SSRT. This occurred because hydrogen was continuously supplied during deformation, exceeding the critical concentration even in the center regions, leading to quasi-cleavage fractures marked by localized cleavage and tearing ridges. Thermal desorption analysis (TDA) confirmed that a greater amount of hydrogen was trapped at dislocations during in situ hydrogen-charged SSRT, intensifying hydrogen embrittlement, even with a shorter hydrogen charging duration. These findings highlight the importance of selecting appropriate hydrogen charging methods and understanding the hydrogen embrittlement behavior of linepipe steels.https://www.mdpi.com/2075-4701/14/12/1397linepipe steelelectrochemicalhydrogen embrittlementmicrostructurethermal desorption analysis (TDA)
spellingShingle Dong-Kyu Oh
Min-Seop Jeong
Seung-Hyeok Shin
Byoungchul Hwang
Effect of Hydrogen on Tensile Properties and Fracture Behavior of Two High-Strength American Petroleum Institute Linepipe Steels
Metals
linepipe steel
electrochemical
hydrogen embrittlement
microstructure
thermal desorption analysis (TDA)
title Effect of Hydrogen on Tensile Properties and Fracture Behavior of Two High-Strength American Petroleum Institute Linepipe Steels
title_full Effect of Hydrogen on Tensile Properties and Fracture Behavior of Two High-Strength American Petroleum Institute Linepipe Steels
title_fullStr Effect of Hydrogen on Tensile Properties and Fracture Behavior of Two High-Strength American Petroleum Institute Linepipe Steels
title_full_unstemmed Effect of Hydrogen on Tensile Properties and Fracture Behavior of Two High-Strength American Petroleum Institute Linepipe Steels
title_short Effect of Hydrogen on Tensile Properties and Fracture Behavior of Two High-Strength American Petroleum Institute Linepipe Steels
title_sort effect of hydrogen on tensile properties and fracture behavior of two high strength american petroleum institute linepipe steels
topic linepipe steel
electrochemical
hydrogen embrittlement
microstructure
thermal desorption analysis (TDA)
url https://www.mdpi.com/2075-4701/14/12/1397
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