About solute drag
Posted: Fri Nov 01, 2013 7:35 am
Dear Bernd
Long time no question about MICRESS
Today i came back to ask about solute drag model in the MICRESS.
First of all, I want to ask about the meaning of each line in the dri file as given below.
...
# Options: constant temp_dependent dg_dependent
temp_dependent
# File for kinetic coefficient between phases 1 and 2?
Mobility_ag.txt
# critical velocity [micrometer/s]
6.00000E-07
# transition range deltaV [micrometer/s]
1.00000E-07
# Drag factor (real) < 1.
0.50000
...
In this case, I use temperature dependence of mobility data and give "solute drag" assumption to the boundary between phase 1 (Ferrite) and phase 2(Austenite). I want to know the meaning of last three lines such as "critical velocity", "transition range..." and "Darg factor".
Secondly, as known that the solute drag force is proportional to the solute amount in the boundaries which means that if the solute content is high in the vicinity of boundaries the velocity of the boundary will get slower. And i experimentally observed that the solute (in this case Mn) is strongly segregated at the interphase boundary of Ferrite and Austenite. In my simulation, i solidify the system first from 1760K to 746K and reheated to 1550K holding there for 1 hour. I directly use diffusion data from thermo_calc and "multi" option is used in the dri file for all alloying elements such as Fe, Al, Si, Mn and C. And i do not use the enhanced diffusion assumption such as boundary diffusion. The result gives me quite nice Mn partitioning in the Ferrite and Austenite as seen above. However, boundary segregation of Mn does not appear in the simulation result. I will attach one of the experimental and simulation result of Mn content.
Do you have any way to simulate boundary segregation that is closed to real situation? What about using enhanced diffusion assumption along grain boundary? To get the above simulation result, i put the initial Ferrite grain at the both bottom of domain and assumed "ssii" for the both of boundary condition. I found that there is only large segregation of Mn at the very middle part of domain where the region becomes austenite during cooling.
Thank you
Seawoong Lee
Long time no question about MICRESS
Today i came back to ask about solute drag model in the MICRESS.
First of all, I want to ask about the meaning of each line in the dri file as given below.
...
# Options: constant temp_dependent dg_dependent
temp_dependent
# File for kinetic coefficient between phases 1 and 2?
Mobility_ag.txt
# critical velocity [micrometer/s]
6.00000E-07
# transition range deltaV [micrometer/s]
1.00000E-07
# Drag factor (real) < 1.
0.50000
...
In this case, I use temperature dependence of mobility data and give "solute drag" assumption to the boundary between phase 1 (Ferrite) and phase 2(Austenite). I want to know the meaning of last three lines such as "critical velocity", "transition range..." and "Darg factor".
Secondly, as known that the solute drag force is proportional to the solute amount in the boundaries which means that if the solute content is high in the vicinity of boundaries the velocity of the boundary will get slower. And i experimentally observed that the solute (in this case Mn) is strongly segregated at the interphase boundary of Ferrite and Austenite. In my simulation, i solidify the system first from 1760K to 746K and reheated to 1550K holding there for 1 hour. I directly use diffusion data from thermo_calc and "multi" option is used in the dri file for all alloying elements such as Fe, Al, Si, Mn and C. And i do not use the enhanced diffusion assumption such as boundary diffusion. The result gives me quite nice Mn partitioning in the Ferrite and Austenite as seen above. However, boundary segregation of Mn does not appear in the simulation result. I will attach one of the experimental and simulation result of Mn content.
Do you have any way to simulate boundary segregation that is closed to real situation? What about using enhanced diffusion assumption along grain boundary? To get the above simulation result, i put the initial Ferrite grain at the both bottom of domain and assumed "ssii" for the both of boundary condition. I found that there is only large segregation of Mn at the very middle part of domain where the region becomes austenite during cooling.
Thank you
Seawoong Lee