Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels
Abstract Duplex stainless steels (DSS) are used in off-shore platforms due to their good properties resulting from the combination of two phases, namely austenite and ferrite. Secondary intermetallic phases, such as alpha prime (α´) and sigma (σ), which are harmful, can be formed at temperatures abo...
| Main Authors: | , , , |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Associação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)
2020-10-01
|
| Series: | Materials Research |
| Subjects: | |
| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392020000500208&tlng=en |
| _version_ | 1798019932027355136 |
|---|---|
| author | Elki C. Souza Raiched F. Bueno Carlos A. Fortulan João M. D. A. Rollo |
| author_facet | Elki C. Souza Raiched F. Bueno Carlos A. Fortulan João M. D. A. Rollo |
| author_sort | Elki C. Souza |
| collection | DOAJ |
| description | Abstract Duplex stainless steels (DSS) are used in off-shore platforms due to their good properties resulting from the combination of two phases, namely austenite and ferrite. Secondary intermetallic phases, such as alpha prime (α´) and sigma (σ), which are harmful, can be formed at temperatures above 400 °C, or by a casting process. This study investigates the formation of sigma phase by thermal cycles running in a dilatometer (800 °C, 850 °C, 900 °C and 1,000 °C) for 1h, and at 850 °C for 3h and 7h. The optical microscopy of the DSS microstructure subjected to 800, 850 and 900 °C for one hour revealed a small fraction of σ phase with nucleation in the contour of ferrite/austenite phases, and tests by ferritoscope indicated a decrease (~4%) in a magnetic fraction (ferrite). However, samples subjected to dilatometric cycles at 850 °C for 3 hours showed an 18% decrease in the magnetic phase and quantitative metallography revealed a 33% fraction of σ phase precipitated in the ferrite phase. Tests conducted at 850 ºC for 7 hours indicated a high fraction of σ phase precipitated (approximately 50%), starting in the grain boundary, austenite/ferrite, and advancing in ferrite grain. |
| first_indexed | 2024-04-11T16:49:26Z |
| format | Article |
| id | doaj.art-e9e5ef161adb466695defd2b3ace9300 |
| institution | Directory Open Access Journal |
| issn | 1516-1439 |
| language | English |
| last_indexed | 2024-04-11T16:49:26Z |
| publishDate | 2020-10-01 |
| 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-e9e5ef161adb466695defd2b3ace93002022-12-22T04:13:29ZengAssociação Brasileira de Metalurgia e Materiais (ABM); Associação Brasileira de Cerâmica (ABC); Associação Brasileira de Polímeros (ABPol)Materials Research1516-14392020-10-0123510.1590/1980-5373-mr-2020-0252Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless SteelsElki C. Souzahttps://orcid.org/0000-0003-2063-7423Raiched F. Buenohttps://orcid.org/0000-0002-5888-254XCarlos A. Fortulanhttps://orcid.org/0000-0002-2259-9910João M. D. A. Rollohttps://orcid.org/0000-0003-0768-644XAbstract Duplex stainless steels (DSS) are used in off-shore platforms due to their good properties resulting from the combination of two phases, namely austenite and ferrite. Secondary intermetallic phases, such as alpha prime (α´) and sigma (σ), which are harmful, can be formed at temperatures above 400 °C, or by a casting process. This study investigates the formation of sigma phase by thermal cycles running in a dilatometer (800 °C, 850 °C, 900 °C and 1,000 °C) for 1h, and at 850 °C for 3h and 7h. The optical microscopy of the DSS microstructure subjected to 800, 850 and 900 °C for one hour revealed a small fraction of σ phase with nucleation in the contour of ferrite/austenite phases, and tests by ferritoscope indicated a decrease (~4%) in a magnetic fraction (ferrite). However, samples subjected to dilatometric cycles at 850 °C for 3 hours showed an 18% decrease in the magnetic phase and quantitative metallography revealed a 33% fraction of σ phase precipitated in the ferrite phase. Tests conducted at 850 ºC for 7 hours indicated a high fraction of σ phase precipitated (approximately 50%), starting in the grain boundary, austenite/ferrite, and advancing in ferrite grain.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392020000500208&tlng=enDuplex Stainless Steel (DSS)DilatometerSigma PhaseQuantitative MetallographyFerristoscopeIntermetallic Phases |
| spellingShingle | Elki C. Souza Raiched F. Bueno Carlos A. Fortulan João M. D. A. Rollo Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels Materials Research Duplex Stainless Steel (DSS) Dilatometer Sigma Phase Quantitative Metallography Ferristoscope Intermetallic Phases |
| title | Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels |
| title_full | Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels |
| title_fullStr | Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels |
| title_full_unstemmed | Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels |
| title_short | Dilatometric Cycles in the Study of Precipitation of Intermetallic Phases in Duplex Stainless Steels |
| title_sort | dilatometric cycles in the study of precipitation of intermetallic phases in duplex stainless steels |
| topic | Duplex Stainless Steel (DSS) Dilatometer Sigma Phase Quantitative Metallography Ferristoscope Intermetallic Phases |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392020000500208&tlng=en |
| work_keys_str_mv | AT elkicsouza dilatometriccyclesinthestudyofprecipitationofintermetallicphasesinduplexstainlesssteels AT raichedfbueno dilatometriccyclesinthestudyofprecipitationofintermetallicphasesinduplexstainlesssteels AT carlosafortulan dilatometriccyclesinthestudyofprecipitationofintermetallicphasesinduplexstainlesssteels AT joaomdarollo dilatometriccyclesinthestudyofprecipitationofintermetallicphasesinduplexstainlesssteels |