Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels



Título del documento: Evaluation of the low corrosion resistant phase formed during the sigma phase precipitation in duplex stainless steels
Revista: Materials research
Base de datos: PERIÓDICA
Número de sistema: 000312403
ISSN: 1516-1439
Autores: 1
1
Instituciones: 1Universidade de Sao Paulo, Escola Politecnica, Sao Paulo. Brasil
Año:
Periodo: Oct
Volumen: 2
Número: 4
Paginación: 239-247
País: Brasil
Idioma: Inglés
Tipo de documento: Artículo
Enfoque: Descriptivo
Resumen en inglés 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
Disciplinas: Ingeniería,
Física y astronomía
Palabras clave: Ingeniería de control,
Mecánica, elasticidad y reología,
Acero inoxidable,
Corrosión
Keyword: Engineering,
Physics and astronomy,
Control engineering,
Mechanics, elasticity and rheology,
Stainless steel,
Corrosion
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