This paper may help. N. Nakada et al, Difference in transformation behavior between ferrite

and austenite formations in medium manganese steel, http://dx.doi.org/10.1016/j.actamat.2013.10.067

Hi David,

you can assume martensite (alfa prime) as bcc.  It can be considered that martensite and ferrite has same thermodynamical properties. You may found an example by Nakada (2014) in Acta Materialia. However, Dmitrieva (2011) proposed that kinetic parameters should be revised due to the defect structure and distortion of the martensite.

There are few tricks to simulate the change in carbon solubillity in the martensite:

-the first is to change the carbon mobility in the BCC phase, as shown for Mn in Dmitrieva (2011) paper. 

-Use a labyrinth factor normally use in the homogenisation model to slow down the diffusion of carbon in BCC in order to simulate the "trapping effect" of the martensite.

These two ways may help, but of course it will remain a BCC phase, there is no way to accurate predict the martensite behaviour in DICTRA since the data are only available for thermodynamic stable phases. The only real solution will be to create a new database from scratch I guess.

Hope it will help.

/Alvise

Reply to Alvise;

Mobility can be changed, however not carbon solubility.

I am working on it to create a new database.