Process Metallurgy Calculator: Options Tab

These settings are for the Process Metallurgy Calculator and are located on the Configuration window → Options tab. Only unique settings are described below.

You can change these settings locally for a specific Calculator or globally for some defaults in the Options window (a different location than the tab).

To open the Options window:

  • Windows: Select Tools → Options menu icon Options.
  • Mac: Select Thermo-Calc <version> → Preferences or Settings or press <⌘> on the keyboard.

then click the Graphical Mode tab and the Process Metallurgy node in the tree.

Equilibrium Simulation: Conditions Tab

Material Manager

Use the Material group and Material lists to create and delete material groups, as well as delete material compositions that are saved from the Process Metallurgy Calculator. It is useful for frequently used materials.

See Working with the Material Manager for details.

  • Material group: To create or delete a group, choose it from this list, e.g. Steel, Slag, or Gas. The Steel group is simply a generic Metal group. You can create other user-defined metal groups and then these are listed. Click Create group or Delete group as required to manage the list.
  • Material: To delete a material, choose the group type then select the material composition to delete. For example, select the Slag material group, then choose the Example Slag material and click Delete material to remove it from all lists.

Process Material Equilibrium and Grid

Under Process Material Equilibrium and Grid, the default uses the Global test preferred option for Equilibrium simulations and the Local minimization preferred option for Process simulations.

The Minimization Strategy setting is used to ensure that the most stable minimum under the specified conditions is computed.

With either the Global test preferred or Local minimization preferred setting, the program cycles through options before it gives up:

  • For Global test preferred the minimization starts with a global test and if that fails it runs full global minimization.
  • For Local minimization preferred the minimization starts with a local minimization, in case of failure it tries a global test and finally a full global minimization.

If you choose Local minimization only or Global minimization only, the program just tries the one setting and gives up if it fails.

For general information about global minimization, see the topic related to the Console Mode command, GLOBAL_MINIMIZATION.

Under Process Material Equilibrium and Grid, the default for the Max no. of iterations is that the program tries 2000 iterations before it gives up.

The default Required accuracy is 1.0E-6. This is a relative accuracy, and the program requires that the relative difference in each variable must be lower than this value before it has converged. A larger value normally means fewer iterations but less accurate solutions. The value should be at least one order of magnitude larger than the machine precision.

Under Process Material Equilibrium and Grid, the default Smallest fraction is 1.0E-16. If this value fails, the program tries other values. This is the value assigned to constituents that are unstable.

The default value is for all phases except for the IDEAL phase with one sublattice site (such as the GAS mixture phase in many databases) where the default value is always as 1E-30.

Under Process Material Equilibrium and Grid, from the Max grid points list choose:

  • Coarse for 2000 grid points, the default,
  • Medium for 20,000 grid points,
  • Fine for 200,000 grid points, or
  • Custom to set your own number of grid points.

Under Process Material Equilibrium and Grid, the Approximate driving force for metastable phases checkbox is selected by default, which means the metastable phases are included in all iterations. However, these may not have reached their most favorable composition and thus these driving forces may be only approximate.

Under Process Material Equilibrium and Grid, the Force positive definite phase Hessian checkbox is selected by default and this setting determines how to reach the minimum of an equilibrium state.

Under Process Material Equilibrium and Grid, the Control step size checkbox is selected by default and this setting determines how to reach the minimum of an equilibrium state.

Timestep Control

This section is used with the Process simulation calculations. Read About Dynamic Time Stepping to better understand these settings.

Under Timestep control, enter numerical values in the fields for the Timestep:

  • Initial %
  • Smallest allowed in seconds (s)
  • Max % of duration

Under Timestep control, in the field enter the Max temperature change per time step in Kelvin (K).