Effect of short-time overheating in the morphology of primary carbides network in Nb and NbTi-modified HP stainless steels steam reforming tubes
Commercial bulk hydrogen is mainly produced in petrochemical steam reforming furnaces inside centrifugally cast Nb-modified HP austenitic stainless steels tubes, which operate at temperatures above 900 °C. In-service aging causes well known microstructural modifications such as the transformation of...
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| Format: | Article |
| Language: | English |
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Elsevier
2023-01-01
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| Series: | Journal of Materials Research and Technology |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2238785422018348 |
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| author | Mario Luiz Cruz Nascimento Flávia da Cruz Gallo Fábio dos Santos Queiroz Matheus Campolina Mendes Carlos Bruno Eckstein Laudemiro Nogueira, Jr. Iain Le May Gabriela Ribeiro Pereira Luiz Henrique de Almeida |
| author_facet | Mario Luiz Cruz Nascimento Flávia da Cruz Gallo Fábio dos Santos Queiroz Matheus Campolina Mendes Carlos Bruno Eckstein Laudemiro Nogueira, Jr. Iain Le May Gabriela Ribeiro Pereira Luiz Henrique de Almeida |
| author_sort | Mario Luiz Cruz Nascimento |
| collection | DOAJ |
| description | Commercial bulk hydrogen is mainly produced in petrochemical steam reforming furnaces inside centrifugally cast Nb-modified HP austenitic stainless steels tubes, which operate at temperatures above 900 °C. In-service aging causes well known microstructural modifications such as the transformation of primary niobium carbides, NbC, into the G-phase (Ni16Nb6Si7). Unexpected operational problems, such as reduced feedstock flow may, in a few minutes, cause severe overheating. These short-time temperature surges, can lead tubes to premature failure often through the formation of large longitudinal cracks. Little is known about the integrity of the tubes that undergo a temperature surge without cracking. Thus, understanding the microstructural changes brought upon by these events becomes extremely important when assessing the reuse of these tubes. In the present work, by means of optical microscopy, scanning electron microscopy and transmission electron microscopy with energy dispersive X-ray spectroscopy, two Nb and NbTi-modified HP steels tubes, which cracked due to high temperature surges, were analyzed. Results show that insitu dissolution of the G-phase in the thermally affected regions causes this phase to be replaced by fine NbC or (NbTi)C precipitates. These microstructural transformations suffered by the tubes during the short-time overheating and cooling cycles are thus presented and discussed in terms of their practical consequences. |
| first_indexed | 2024-04-10T20:18:21Z |
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| id | doaj.art-eee0b75a70df4306beb87e2a21ebdde2 |
| institution | Directory Open Access Journal |
| issn | 2238-7854 |
| language | English |
| last_indexed | 2024-04-10T20:18:21Z |
| publishDate | 2023-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Materials Research and Technology |
| spelling | doaj.art-eee0b75a70df4306beb87e2a21ebdde22023-01-26T04:45:37ZengElsevierJournal of Materials Research and Technology2238-78542023-01-0122382392Effect of short-time overheating in the morphology of primary carbides network in Nb and NbTi-modified HP stainless steels steam reforming tubesMario Luiz Cruz Nascimento0Flávia da Cruz Gallo1Fábio dos Santos Queiroz2Matheus Campolina Mendes3Carlos Bruno Eckstein4Laudemiro Nogueira, Jr.5Iain Le May6Gabriela Ribeiro Pereira7Luiz Henrique de Almeida8Programa de Engenharia Metalúrgica e de Materiais, Universidade Federal Do Rio de Janeiro, Rio de Janeiro/RJ – BrazilPrograma de Engenharia Metalúrgica e de Materiais, Universidade Federal Do Rio de Janeiro, Rio de Janeiro/RJ – Brazil; Corresponding author.Programa de Engenharia Metalúrgica e de Materiais, Universidade Federal Do Rio de Janeiro, Rio de Janeiro/RJ – BrazilCentro Federal de Educação Tecnológica Celso Suckow da Fonseca, Rio de Janeiro/RJ – BrazilPETROBRAS Edisen, Rio de Janeiro/RJ – BrazilPETROBRAS Edisen, Rio de Janeiro/RJ – BrazilMetallurgical Consulting Services Limited, Saskatoon – CanadaPrograma de Engenharia Metalúrgica e de Materiais, Universidade Federal Do Rio de Janeiro, Rio de Janeiro/RJ – BrazilPrograma de Engenharia Metalúrgica e de Materiais, Universidade Federal Do Rio de Janeiro, Rio de Janeiro/RJ – BrazilCommercial bulk hydrogen is mainly produced in petrochemical steam reforming furnaces inside centrifugally cast Nb-modified HP austenitic stainless steels tubes, which operate at temperatures above 900 °C. In-service aging causes well known microstructural modifications such as the transformation of primary niobium carbides, NbC, into the G-phase (Ni16Nb6Si7). Unexpected operational problems, such as reduced feedstock flow may, in a few minutes, cause severe overheating. These short-time temperature surges, can lead tubes to premature failure often through the formation of large longitudinal cracks. Little is known about the integrity of the tubes that undergo a temperature surge without cracking. Thus, understanding the microstructural changes brought upon by these events becomes extremely important when assessing the reuse of these tubes. In the present work, by means of optical microscopy, scanning electron microscopy and transmission electron microscopy with energy dispersive X-ray spectroscopy, two Nb and NbTi-modified HP steels tubes, which cracked due to high temperature surges, were analyzed. Results show that insitu dissolution of the G-phase in the thermally affected regions causes this phase to be replaced by fine NbC or (NbTi)C precipitates. These microstructural transformations suffered by the tubes during the short-time overheating and cooling cycles are thus presented and discussed in terms of their practical consequences.http://www.sciencedirect.com/science/article/pii/S2238785422018348Nb modified HP austenitic stainless steelsSteam reformer tubesTemperature surgesMicrostructural evolutionNiobium carbideG-phase |
| spellingShingle | Mario Luiz Cruz Nascimento Flávia da Cruz Gallo Fábio dos Santos Queiroz Matheus Campolina Mendes Carlos Bruno Eckstein Laudemiro Nogueira, Jr. Iain Le May Gabriela Ribeiro Pereira Luiz Henrique de Almeida Effect of short-time overheating in the morphology of primary carbides network in Nb and NbTi-modified HP stainless steels steam reforming tubes Journal of Materials Research and Technology Nb modified HP austenitic stainless steels Steam reformer tubes Temperature surges Microstructural evolution Niobium carbide G-phase |
| title | Effect of short-time overheating in the morphology of primary carbides network in Nb and NbTi-modified HP stainless steels steam reforming tubes |
| title_full | Effect of short-time overheating in the morphology of primary carbides network in Nb and NbTi-modified HP stainless steels steam reforming tubes |
| title_fullStr | Effect of short-time overheating in the morphology of primary carbides network in Nb and NbTi-modified HP stainless steels steam reforming tubes |
| title_full_unstemmed | Effect of short-time overheating in the morphology of primary carbides network in Nb and NbTi-modified HP stainless steels steam reforming tubes |
| title_short | Effect of short-time overheating in the morphology of primary carbides network in Nb and NbTi-modified HP stainless steels steam reforming tubes |
| title_sort | effect of short time overheating in the morphology of primary carbides network in nb and nbti modified hp stainless steels steam reforming tubes |
| topic | Nb modified HP austenitic stainless steels Steam reformer tubes Temperature surges Microstructural evolution Niobium carbide G-phase |
| url | http://www.sciencedirect.com/science/article/pii/S2238785422018348 |
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