Pearlite Property Model Settings

The Pearlite Property Model, available with the Property Model Calculator and the Steel Model Library, calculates the thermodynamics and kinetics of pearlite formation from austenite during isothermal heat treatment.

The included elements in the Pearlite Property Model are Fe (dependent element), C, Mn, Cr, Mo, W, Si, Al, Ni, Co. Other elements are neglected by weight percent.

For the Ferrite, Bainite, and Pearlite Property Models, it is also useful to review the Recommended Composition Ranges for Steel Models.

About the Pearlite Property Model

For an example see PM_Fe_03: Fe-C-Mn Pearlite.

To run calculations with the Steel Models requires a valid maintenance license plus licenses for both the TCFE (version 9 and newer) and MOBFE (version 4 and newer) databases. Also see our website to learn more about the Steel Model Library and other related examples.

Configuration Settings

The settings are found on the Property Model Calculator when Pearlite is selected under Steel Models.

When working in the Configuration window, click the Description tab for more information about the Model.

For the details about the Condition Definitions, Calculation Type, Timeout in minutes, Parallel Calculation, and other calculation associated settings, see Property Model Calculator: Configuration Window Settings.

Select an option from the Austenite composition from list:

  • Nominal composition uses the system composition as austenite composition.
  • Equilibrium composition at austenizing temperature. Select to enter an Austenitizing temperature. The austenite composition is determined from an equilibrium calculation at the austenitizing temperature (if austenite is stable). This option is useful when austenite coexists with other phase(s), e.g. primary carbide, before the transformation(s) being calculated starts. But the Model only considers the effect of other phase(s) on austenite composition.

This setting is available when Equilibrium composition at austenitizing temperature is selected from the Austenite composition from list.

Enter an Austentizing temperature in the field. The unit is the same as that selected under Condition Definitions.

Enter the Grain size of the austenite in micrometers (μm). The default is 100 μm.

This setting is available when the Pearlite selected checkbox is selected.

Select an option from the Criterion list to determine the pearlite growth condition. This list is called Pearlite criterion for the CCT Diagram and TTT Diagram Property Models.

  • For Maximize growth rate, pearlite growth rate is maximized with respect to lamellar spacing (and for optimal pearlite, partition coefficients of substitutional alloying elements between ferrite and cementite). The calculation gives maximal growth rate and minimal lamellar spacing. This is the default criterion.
  • For Maximize Gibbs energy dissipation rate, Gibbs energy dissipation rate is maximized with respect to lamellar spacing (and for optimal pearlite, partition coefficients of substitutional alloying elements between ferrite and cementite). The calculation gives a smaller growth rate than the maximal, and a larger lamellar spacing than the minimal, which may better represent the average growth rate and lamellar spacing of all pearlite colonies in the material.

This setting is available when the Pearlite selected checkbox is selected. It is used to determine how substitutional alloying elements partition between ferrite and cementite in pearlite. Select an option from the Pearlite mode list.

  • For Optimal pearlite, the partitioning of substitutional alloying elements between ferrite and cementite is optimized according to the Criterion while keeping carbon equilibrium between the two phases. This is the default mode. This mode realizes a smooth transition between ortho-pearlite and para-pearlite.
  • For Para-pearlite, ferrite and cementite are in para-equilibrium where substitutional alloying elements do not partition and carbon reaches equilibrium.
  • For Ortho-pearlite, ferrite and cementite are in ortho-equilibrium.

Plot Renderer Settings

Plot Renderer, Plot Renderer: Configuration Settings, and Plot Type: TTT Mode

When setting up your calculation on the Plot Renderer and/or Table Renderer, the following axis variables are available for the conditions defined on the Property Model Calculator.

  • Temperature
  • Start time (2% pearlite)
  • Half time (50% pearlite)
  • Finish time (98% pearlite)
  • Growth rate [m/s]
  • Lamellar spacing [m]
  • Cementite molar fraction in pearlite
  • Driving force of pearlite formation [J/mol]