Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels
The duplex stainless steels, having a volumetric fraction of 50% ferrite and 50% austenite, conciliate high corrosion resistance with good mechanical properties. But, in many circumstances different phase transformations may occur, such as that responsible for sigma phase precipitation, which make t...
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| Format: | Article |
| Language: | English |
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Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
1999-10-01
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| Series: | Materials Research |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14391999000400002&tlng=en |
| _version_ | 1798015226630635520 |
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| author | Darlene Yuko Kobayashi Stephan Wolynec |
| author_facet | Darlene Yuko Kobayashi Stephan Wolynec |
| author_sort | Darlene Yuko Kobayashi |
| collection | DOAJ |
| description | The duplex stainless steels, having a volumetric fraction of 50% ferrite and 50% austenite, conciliate high corrosion resistance with good mechanical properties. But, in many circumstances different phase transformations may occur, such as that responsible for sigma phase precipitation, which make the steel susceptible to localized corrosion. During the sigma phase precipitation a new austenitic phase is formed with a very low corrosion resistance. In the present research the composition of this new austenitic phase was evaluated in four duplex stainless steels, with different Mo, N and Cu contents. After the solution anneal at 1050 °C, samples of these steels were aged at 850 °C during 1 h and 5 h for sigma phase precipitation. Using the ferritoscope and an image analyzer it was possible to determine the volumetric fractions of ferrite and sigma phase, respectively, while those of austenite and the new austenitic phase were determined by difference to 100% volume. Finally, by using mass balance it was possible to determine theoretically the composition of the new austenitic phase. This phase is poor in Cr and Mo free, which explains its poor corrosion resistance. |
| first_indexed | 2024-04-11T15:30:08Z |
| format | Article |
| id | doaj.art-2595bb12afe647f8b10b1df2c0934ef4 |
| institution | Directory Open Access Journal |
| issn | 1516-1439 |
| language | English |
| last_indexed | 2024-04-11T15:30:08Z |
| publishDate | 1999-10-01 |
| publisher | Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol) |
| record_format | Article |
| series | Materials Research |
| spelling | doaj.art-2595bb12afe647f8b10b1df2c0934ef42022-12-22T04:16:09ZengAssociação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)Materials Research1516-14391999-10-012423924710.1590/S1516-14391999000400002Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steelsDarlene Yuko Kobayashi0Stephan Wolynec1Centro Tecnológico da Marinha em São PauloUniversidade de São PauloThe duplex stainless steels, having a volumetric fraction of 50% ferrite and 50% austenite, conciliate high corrosion resistance with good mechanical properties. But, in many circumstances different phase transformations may occur, such as that responsible for sigma phase precipitation, which make the steel susceptible to localized corrosion. During the sigma phase precipitation a new austenitic phase is formed with a very low corrosion resistance. In the present research the composition of this new austenitic phase was evaluated in four duplex stainless steels, with different Mo, N and Cu contents. After the solution anneal at 1050 °C, samples of these steels were aged at 850 °C during 1 h and 5 h for sigma phase precipitation. Using the ferritoscope and an image analyzer it was possible to determine the volumetric fractions of ferrite and sigma phase, respectively, while those of austenite and the new austenitic phase were determined by difference to 100% volume. Finally, by using mass balance it was possible to determine theoretically the composition of the new austenitic phase. This phase is poor in Cr and Mo free, which explains its poor corrosion resistance.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14391999000400002&tlng=enduplex stainless steelssigma phaseselective corrosionlocalized corrosion |
| spellingShingle | Darlene Yuko Kobayashi Stephan Wolynec Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels Materials Research duplex stainless steels sigma phase selective corrosion localized corrosion |
| title | Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels |
| title_full | Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels |
| title_fullStr | Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels |
| title_full_unstemmed | Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels |
| title_short | Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels |
| title_sort | evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels |
| topic | duplex stainless steels sigma phase selective corrosion localized corrosion |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14391999000400002&tlng=en |
| work_keys_str_mv | AT darleneyukokobayashi evaluationofthelowcorrosionresistantphaseformedduringthesigmaphaseprecipitationinduplexstainlesssteels AT stephanwolynec evaluationofthelowcorrosionresistantphaseformedduringthesigmaphaseprecipitationinduplexstainlesssteels |