Solidification microsegregation and hot ductility of Fe-Mn-C-Al-xNb TWIP steels

Abstract

The influence of Nb addition on casting microstructures and high-temperature mechanical properties of Fe-Mn-C-Al-xNb TWIP steels was analyzed by phase-field modeling and experiments. Phase-field simulations showed that Mn, Nb, and C are enriched in inter-dendritic regions while Al is enriched in dendritic regions during solidification process of the investigated TWIP steels. Both phase-field simulations and microstructural characterization show that NbC precipitates are preferentially present near inter-dendritic boundaries. Nb addition slightly reduces hot ductility of the investigated steel at 1173 K (900 degrees C) while the Nb-added TWIP steels show better hot-ductility than the reference steel for deformation temperatures above 1373 K (1100 degrees C). NbC precipitates and inter-dendritic distances appear to be the most important variables that affect hot-ductility behavior of the investigated TWIP steels. (C) The Minerals, Metals & Materials Society and ASM International 2018.