Engenharia de Materiais
URI permanente desta comunidadehttps://repositorio.fei.edu.br/handle/FEI/17
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2 resultados
Resultados da Pesquisa
- Use of composition profiles near sigma phase for assessment of localized corrosion resistance in a duplex stainless steel(2019) Magnabosco R.; da Costa Morais L.; dos Santos D.C.© 2018 Elsevier LtdPitting corrosion potential of a UNS S31803 duplex stainless steel (DSS) heat treated between 750 °C and 850 °C at different aging times was related to the extent of the Cr- and Mo-depleted areas at sigma-ferrite and sigma-austenite interfaces, estimated using DICTRA® simulations. It is possible to describe the sigma formation kinetics using a model that assumes a spherical region of austenite, with radius equivalent to the mean intercept of austenite islands, surrounded by ferrite. Composition profiles at sigma-ferrite and sigma-austenite interfaces were calculated, allowing the evaluation of the degree of depletion in Cr and Mo at sigma interfaces. There is a reduction of pitting potential with increase of the degree of depletion, characterized as the weighted sum of depleted areas in Cr and Mo composition profiles, making possible the assessment of the localized corrosion resistance of aged DSS through simulation of sigma phase formation.
- Experimental investigations and DICTRA® simulation of sigma phase formation in a duplex stainless steel(2017) Morais L.D.C.; Magnabosco R.© 2017 Elsevier LtdSigma phase formation in an UNS S31803 duplex stainless steel aged at 940 °C was evaluated by computational simulation in DICTRA® software, using MOB2 diffusion database and TCFE8 thermodynamic database. Simulation results were compared to experimental tests. Two models were tested in DICTRA® software: in model 1 sigma phase are placed between ferrite and austenite, and in model 2 sigma is placed at one side of ferrite region, and austenite on the other. The volume fraction of sigma and ferrite phases obtained in model 1 showed adherence to the experimental results up to 7200 s (2 h) of simulation, indicating the ability of the model in the description of early stages of sigma formation. Model 2 showed good agreement with experimental data up to 86,400 s (24 h) of simulation. The composition profile obtained by the simulation of the model 1 represented better the impoverishment in Cr and Mo in ferrite/sigma and austenite/sigma interfaces, while the profiles obtained by the simulation of model 2 described better the partition of the chemical elements between austenite and ferrite during sigma formation.