|About this Abstract
||2016 TMS Annual Meeting & Exhibition
||Phase Transformations in Multi-component Systems: An MPMD Symposium Honoring Gary R. Purdy
||Evolution of Mn/Cr Composition Gradients in Cementite during Annealing of DP Steels
||Marc Moreno, Hugo Van Landeghem, Jaafar Ghanbaja, Julien Teixeira, Frédéric Bonnet, Sébastien Y.P. Allain
|On-Site Speaker (Planned)
The annealing process of cold-rolled Dual-Phase steels involves numerous mechanisms operating in highly coupled manners during heating as recovery/recrystallization of ferrite, globularisation/ripening/composition evolution of carbides and finally austenite transformation.
The microstructure evolutions of studied steel (90C-1800Mn-200Si-200Cr) have been investigated after interrupted annealing thermal cycles thanks to conventional SEM and analytical TEM (JEM-ARM200F). The local compositions in the cementite have been measured by EELS (EFTEM) and EDX with an excellent spatial resolution.
In the as rolled state, cementite particles already present Mn/Cr composition gradients inherited from the hot rolled processing schedule (coiling in particular). The U shape profiles are interpreted using current models of the pearlitic transformation. During heating, the gradient intensity decreases due to diffusion and varying partitioning mechanism between cementite and ferrite predicted by thermodynamics. Coupled interactions are observed with Rayleigh instabilities (fragmentation of cementite lamellae). The role of gradients in cementite on the austenite transformation will be discussed.
||Planned: A print-only volume