Characterization of the austenite reformation mechanisms as a function of the initial ferritic state in a UNS S32304 duplex stainless steel.
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2017
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Aiming to better understand the effects of heat treatment parameters on Ferrite-Austenite phase
transformation in a 2304 duplex stainless steel different thermal cycles were applied to this steel in
a quenching dilatometer. The obtained microstructures were characterized by optical microscopy,
transmission electron microscopy and electron backscatter diffraction. It was noticed that the austenite
formation mechanism is strongly dependent on initial ferritized state. If the initial structure is completely
ferritized, the nitrogen supersaturated solid solution leads to chromium nitrides precipitation and the
rate of austenite nucleation decreases. For higher cooling rates, the ferrite grain boundaries control
the austenite nucleation rate. The higher the ferrite grain size, the lower the final austenite fraction.
If the steel is cooled from a partial ferritized state, the ferrite-austenite phase boundaries work as
austenite nucleation site and the austenite growth rate is favored due to the high interfacial energy
and the austenitic structures becomes coarser.
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Duplex stainless steel, Ferrite austenite, Phase transformation
Citação
MAGALHÃES, C. H. X. M. et al. Characterization of the austenite reformation mechanisms as a function of the initial ferritic state in a UNS S32304 duplex stainless steel. Materials Research-Ibero-american Journal of Materials, v. 21, p. 1-10, 2017. Disponível em: <http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392017005043108&lng=es&nrm=iso>. Acesso em: 29 set. 2017.