Carburization of austenitic and ferritic stainless steels in liquid sodium: Comparison between experimental observations and simulations. (October 2019)

• Record Type: Journal Article
• Authors: Romedenne, M.; Rouillard, F.; Hamon, D.; Malard, B.; Monceau, D.
• Is Part Of: Corrosion science. Volume 159(2019)
• Publication Date: 2019-10
• Subjects: Stainless steels -- Carburization -- EPMA -- X-ray diffraction -- Modelling studies; Corrosion and anti-corrosives -- Periodicals; 620.11223
• DOI: 10.1016/j.corsci.2019.108147
• Languages: English
• ISSNs: 0010-938X

Abstract

Highlights: Different precipitation behaviors were identified between three stainless steel grades using X-ray transmission synchrotron diffraction. The specimens were heavily carburized in grains and at grain boundaries. However, equilibrium of precipitation was not reached. The blocking effect of carbides had to be considered and was observed to evolve with time and microstructure. Precipitation at grain boundaries could not be simulated with the used model. Abstract: Three steels were exposed in carburizing sodium at 600 and 650 °C. The kinetics and extent of carburization were characterized. Numerical simulations using the coupled thermodynamic-kinetic modeling software DICTRA were performed. It was proposed that the observed carbon diffusion profiles were induced by the combined diffusion of carbon in the grains and at grain boundaries coupled with the slow formation of carbides. The blocking effect of carbides on the carbon diffusion was observed to evolve as a function of time and microstructure. Acceptable agreement between experimental and simulated intragranular carbon profiles was achieved by optimizing the labyrinth factor and phases.