Localised creep cavitation on boron nitride in the heat affected zone of 9% Cr tempered martensitic steel welds
An excessive concentration of boron in the 9% Cr tempered martensitic steels alloyed with nitrogen has a detrimental effect on creep performance, as relatively large boron nitride phases are formed and can act as the preferred sites for cavity nucleation. In the current research, a systematic invest...
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doaj-9d0d02f2bac64316916561e9013edc892020-11-25T04:04:11ZengElsevierMaterials & Design0264-12752020-11-01196109046Localised creep cavitation on boron nitride in the heat affected zone of 9% Cr tempered martensitic steel weldsX. Xu0J.A. Siefert1J.D. Parker2R.C. Thomson3Department of Materials, Loughborough University, Loughborough, LE11 3TU, UK; Corresponding author.EPRI, 1300 Harris Boulevard, Charlotte, North, Carolina, 28262, USAEPRI, 1300 Harris Boulevard, Charlotte, North, Carolina, 28262, USADepartment of Materials, Loughborough University, Loughborough, LE11 3TU, UK; Corresponding author.An excessive concentration of boron in the 9% Cr tempered martensitic steels alloyed with nitrogen has a detrimental effect on creep performance, as relatively large boron nitride phases are formed and can act as the preferred sites for cavity nucleation. In the current research, a systematic investigation has been performed documenting details of creep damage in the heat affected zone of a weld joint constructed by using a 9% Cr Grade 92 steel. A combination of correlative characterisation techniques has been applied to monitor and quantify the evolution of creep damage within the heat affected zone through the entire creep life. The utilisation of cryo-fractography, two-dimensional electron-based microscopic characterisation and three-dimensional tomography based on focused ion beam microscopy have confirmed the close association between creep cavities and boron nitride phases from the initial stage of creep. It is revealed that the thermal transients imposed during welding result in the decohesion at the interface of boron nitrides with the surrounding matrix. This decohesion is a result of significant thermo-mechanical mismatch between boron nitrides and the tempered martensitic matrix. The voids initiated at these locations grow and eventually link-up during creep exposure, leading to cracking and fracture.http://www.sciencedirect.com/science/article/pii/S02641275203058159% Cr tempered martensitic steelHigh temperature creepLocalised cavitationBoron nitrideHeat affected zone |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
X. Xu J.A. Siefert J.D. Parker R.C. Thomson |
spellingShingle |
X. Xu J.A. Siefert J.D. Parker R.C. Thomson Localised creep cavitation on boron nitride in the heat affected zone of 9% Cr tempered martensitic steel welds Materials & Design 9% Cr tempered martensitic steel High temperature creep Localised cavitation Boron nitride Heat affected zone |
author_facet |
X. Xu J.A. Siefert J.D. Parker R.C. Thomson |
author_sort |
X. Xu |
title |
Localised creep cavitation on boron nitride in the heat affected zone of 9% Cr tempered martensitic steel welds |
title_short |
Localised creep cavitation on boron nitride in the heat affected zone of 9% Cr tempered martensitic steel welds |
title_full |
Localised creep cavitation on boron nitride in the heat affected zone of 9% Cr tempered martensitic steel welds |
title_fullStr |
Localised creep cavitation on boron nitride in the heat affected zone of 9% Cr tempered martensitic steel welds |
title_full_unstemmed |
Localised creep cavitation on boron nitride in the heat affected zone of 9% Cr tempered martensitic steel welds |
title_sort |
localised creep cavitation on boron nitride in the heat affected zone of 9% cr tempered martensitic steel welds |
publisher |
Elsevier |
series |
Materials & Design |
issn |
0264-1275 |
publishDate |
2020-11-01 |
description |
An excessive concentration of boron in the 9% Cr tempered martensitic steels alloyed with nitrogen has a detrimental effect on creep performance, as relatively large boron nitride phases are formed and can act as the preferred sites for cavity nucleation. In the current research, a systematic investigation has been performed documenting details of creep damage in the heat affected zone of a weld joint constructed by using a 9% Cr Grade 92 steel. A combination of correlative characterisation techniques has been applied to monitor and quantify the evolution of creep damage within the heat affected zone through the entire creep life. The utilisation of cryo-fractography, two-dimensional electron-based microscopic characterisation and three-dimensional tomography based on focused ion beam microscopy have confirmed the close association between creep cavities and boron nitride phases from the initial stage of creep. It is revealed that the thermal transients imposed during welding result in the decohesion at the interface of boron nitrides with the surrounding matrix. This decohesion is a result of significant thermo-mechanical mismatch between boron nitrides and the tempered martensitic matrix. The voids initiated at these locations grow and eventually link-up during creep exposure, leading to cracking and fracture. |
topic |
9% Cr tempered martensitic steel High temperature creep Localised cavitation Boron nitride Heat affected zone |
url |
http://www.sciencedirect.com/science/article/pii/S0264127520305815 |
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