|About this Abstract
||2017 TMS Annual Meeting & Exhibition
||Advanced High-Strength Steels
||Austenite Formation along Dislocations in Medium Manganese Steels
||Margarita Kuzmina, Dirk Ponge, Stefanie Sandl÷bes, Michael Herbig, Dierk Raabe
|On-Site Speaker (Planned)
In a binary martensitic Fe-9wt%Mn alloy with very low carbon content (75 wt ppm) we observe a serrated appearance of the stress-strain curve at 450 ░C and discontinuous yielding after tempering at 450░C. These phenomena have so far mainly been observed in the Fe-C system, where they are referred to as dynamic and static strain ageing, respectively. Correlative TEM/atom probe tomography experiments give direct evidence for pronounced equilibrium segregation of Mn (up to a factor of 3) and the absence of C at dislocations. The tubular-like Mn enriched zone has the chemical composition of austenite when in thermodynamic equilibrium with the present ferrite phase (partitioning). In conjunction with the thermodynamically calculated radius of a subcritical metastable particle of the second phase, we hence suggest that some of the dislocation segments might have undergone segregation-induced phase transformation to austenite.
||Planned: Supplemental Proceedings volume