Re: Recrystallisation
Posted: Thu Mar 25, 2021 8:01 pm
Dear Kamran,
Unfortunately, I am not so much experienced in recrystallisation in general. Thus, I don't know what are typical values of critical reX-energy or dislocation density for nucleation, and also not for the energy threshold for recrystallisation model. Clear is that the latter should be much smaller than typical deformation energies, while the critical reX-energy for nucleation should be somewhere inside the range of deformation energies in order to be somehow selective. The only way of determining these input values is probably by calibration with experimental results...
For calculation of the driving force for phase transformations in MICRESS, the reX-energy difference is added to the chemical driving force. However, for nucleation, you currently can only chose either reX-energy or undercooling. However, as far as I understand, adding strain energy to the driving force for nucleation of austenite would favor nucleation on deformed grains rather than on recrystallized grains. Thus, your observations cannot be explained from an energetic view but must have another reason.
Of course, you can do recrystallisation simulations during isothermal holding. You can also start from a microstructure which has been simulated earlier by using "initial microstructure from restart file" (or "restart structure_only" in earlier MICRESS versions 6.xx).
When creating initial microstructures using the Voronoi construction, only the center positions and the ratio of the radii are important for the outcome. The absolute values of the radii or radii ranges do not enter.
I recommend using an interface thickness of 3-4 cells.
Bernd
Unfortunately, I am not so much experienced in recrystallisation in general. Thus, I don't know what are typical values of critical reX-energy or dislocation density for nucleation, and also not for the energy threshold for recrystallisation model. Clear is that the latter should be much smaller than typical deformation energies, while the critical reX-energy for nucleation should be somewhere inside the range of deformation energies in order to be somehow selective. The only way of determining these input values is probably by calibration with experimental results...
For calculation of the driving force for phase transformations in MICRESS, the reX-energy difference is added to the chemical driving force. However, for nucleation, you currently can only chose either reX-energy or undercooling. However, as far as I understand, adding strain energy to the driving force for nucleation of austenite would favor nucleation on deformed grains rather than on recrystallized grains. Thus, your observations cannot be explained from an energetic view but must have another reason.
Of course, you can do recrystallisation simulations during isothermal holding. You can also start from a microstructure which has been simulated earlier by using "initial microstructure from restart file" (or "restart structure_only" in earlier MICRESS versions 6.xx).
When creating initial microstructures using the Voronoi construction, only the center positions and the ratio of the radii are important for the outcome. The absolute values of the radii or radii ranges do not enter.
I recommend using an interface thickness of 3-4 cells.
Bernd