Influence of interface migration during annealing of martensite/austenite mixtures

Abstract

Tempering of martensite in the absence of carbide precipitation leads to carbon partitioning into retained austenite. If the martensite/austenite interface is assumed to remain stationary during this process, the phase compositions reach a condition that has recently been called constrained carbon equilibrium. If iron atoms are sufficiently mobile at the interface, longer partitioning times may lead to migration of the ferrite/austenite interface. The interface may be expected to move in either direction, depending on the specific details of the phase fractions and compositions controlling the chemical potential of iron at the interface. If interface migration occurs during carbon partitioning, the situation is more complicated and conditions could exist where the interface moves first in one direction and then the other.

Acknowledgements

This work was supported by the NSF through award DMR-0303510, the Laboratory for Iron and Steelmaking at Ghent University, and the sponsors of the Advanced Steel Processing and Products Research Center, an NSF Industry/University Cooperative Research Center. REH acknowledges support from the US Department of Energy (contract DE-AC52-06NA25396).

Notes

†It should be recognized that any interface movement that occurs will create a need for subsequent carbon redistribution, even if carbon partitioning was complete prior to such movement.