Two numerical models have been developed inorder to simulate the reaustenitisation from ferrite/pearlitemicrostructures in Fe-C steels. The first one describes thedissolution of pearlite which takes place just above the eutectoidtemperature. It is based upon a two-dimensional finite elementmethod and an adaptive mesh. The diffusion equation is solved inaustenite (#gamma#) for a typical domain representative of theperiodic structure of ferrite (#alpha#) and cementite (theta#)lamellae. The #alpha#/#gamma# and #theta#/#gamma# interfacesare allowed to move with respect to the local equilibriumcondition including curvature effects via the Gibbs-Thomsoncoefficient. The model is able to predict the dissolution rate, theconcentration field and the shape of the interface at different stagesof the pearlite dissolution. The second model describes thetransformation of proeutectoid ferrite into austenite which followsthe pearlite dissolution in hypoeutectoid steels. The diffusionequation is solved for a domain representative of the #alpha#-#gamma# grain structures, using a finite volume method basedupon a hexagonal grid. The discrete #alpha#/#gamma# boundary isrepresented by special interfacial elements which separate #alpha#-elements from #gamma#-elements. This technique allows tohandle the displacement of the interface while respecting the fluxcondition at the interface. Simulated microstructures showing thedissolution of ferrite regions in the austenite matrix are presentedat different stages of the phase transformation. A reverse TTT-diagram calculated with this 2D model is compared withdilatometric measurements performed at the same heating rates.
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