Decarburization of Fe-C Matrix

Purpose: Learn to perform decarburization simulation at constant temperature with a fixed activity at boundary.

Module: PanDiffusion

Thermodynamic and Mobility Database: Fe-Si-C.tdb

Batch file: Example_#4.14.pbfx

Create a workspace and select the PanDiffusion module following Pandat User's Guide: Workspace;
Load Fe-Si-C.tdb following the procedure in Pandat User's Guide: Load Database , and select all three components;
Click on the menu "PanDiffusion → Diffusion Simulation" or click the icon and set up the calculation condition as shown in Figure 1.
First click the red “X” above Regions to delete Region_2 and leave one Region only.
Click on Region_1 and set the composition as 0.5C-99.5Fe (at%), The length (Diff. Length) as 100 mm, and the # of Grids as 100.
The Thermal History is a period of 10 seconds with a constant temperature at 1000 °C;
Click on Lower Boundary Condition (left edge of Region_1) and select fixed “activity”, and set the Value as “a(C:graphite[*])=0.01”;
In the settings shown in Figure 1, composition profiles at the initial and final stages will be outputted. Click OK to perform calculations.
By default, dissolution simulation gives time-evolution of particle size as output. In order to display composition profile at desired moments, click the blue “+” button next to the “Moments for Profile Outputs” and input a time value. As shown in Figure 1, profiles at 1 second and 5 second will be outputted. Click OK to start calculation;
Details on these options can be found in Pandat User's Guide: Settings in Particle Dissolution Simulation.

Set the scale of the Y axis to be 0.1-0.6 (at%). Remove composition profile of Fe. The calculated composition profiles are displayed in Figure 2Change graph appearance and add text following the procedure in Pandat User's Guide: Property.

Decarburization process in Fcc phase in the Fe-C system. Lower boundary condition is a fixed carbon activity (0.01, Graphite as the reference state).

Figure 1: Setting of the simulation condition

Figure 2: Simulation result of carbon composition profile