Phase Transformation
Depending on the settings at the physics interface level and the space dimension where the physics interface is used, the phase transformation node will contain different sections.
Phase Transformation
The phase transformation defines how one phase forms (the destination phase) at the expense of another (the source phase). Select Source phase ξs and Destination phase ξd from the list of defined phases. Select a Phase transformation model — Leblond–Devaux, Johnson–Mehl–Avrami–Kolmogorov, Kirkaldy–Venugopalan, Koistinen–Marburger, Hyperbolic rate, or User defined.
Leblond–Devaux
Select a Formulation — Time and equilibrium, General coefficients, TTT diagram data, or Parameterized TTT diagram.
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For Time and equilibrium, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify a Time constant τs → d.
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For General coefficients, specify the expressions for Ks → d and Ls → d. For TTT diagram data, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Relative phase fraction X1, and the Transformation time t1.
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For Parameterized TTT diagram, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Relative phase fraction X1. In the TTT Curve 1 section, specify the transformation times tL, tN, and tU corresponding to points on the lower part, the “nose”, and the upper part of the TTT curve at the relative phase fraction X1. Specify the corresponding transformation temperatures TL, TN, and TU, and the TTT curve shape parameters qNL and qNU.
If applicable, select Define temperature limits, and select the Lower temperature limit Tl and the Upper temperature limit Tu from the respective lists. For the User defined options, specify, respectively, expressions for Tl and Tu.
The Equilibrium phase fraction, Lower temperature limit, and Upper temperature limit lists used by phase transformation nodes are populated by values calculated by the Steel Composition node.
Johnson–Mehl–Avrami–Kolmogorov
Select a Formulation — Time, equilibrium and exponent, TTT diagram data, TTT diagram data, fixed exponent, Parameterized TTT diagram, or Parameterized TTT diagram, fixed exponent.
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For Time, equilibrium and exponent, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Time constant τs → d, and the Avrami exponent ns → d.
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For TTT diagram data, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Relative phase fraction X1, the Transformation time t1, the Relative phase fraction X2, and the Transformation time t2.
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For TTT diagram data, fixed exponent, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Avrami exponent ns → d, the Relative phase fraction X1, and the Transformation time t1.
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For Parameterized TTT diagram, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Relative phase fraction X1, and the Relative phase fraction X2. In the TTT Curve 1 section, specify the transformation times tL, tN, and tU corresponding to points on the lower part, the “nose”, and the upper part of the TTT curve at the Relative phase fraction X1. Specify the corresponding transformation temperatures TL, TN, and TU, and the TTT curve shape parameters qNL and qNU. In the TTT Curve 2 section, specify the parameters for the TTT curve at the Relative phase fraction X2.
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For Parameterized TTT diagram, fixed exponent, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Avrami exponent ns → d, and the Relative phase fraction X1. In the TTT Curve 1 section, specify the transformation times tL, tN, and tU corresponding to points on the lower part, the “nose”, and the upper part of the TTT curve at the Relative phase fraction X1. Specify the corresponding transformation temperatures TL, TN, and TU, and the TTT curve shape parameters qNL and qNU.
If the rate term in the phase transformation model is to account for a nonzero initial phase fraction of the source phase, select Include effect of initial phase fraction. If applicable, select Define temperature limits, and select the Lower temperature limit Tl and the Upper temperature limit Tu from the respective lists. For the User defined options, specify, respectively, expressions for Tl and Tu.
Kirkaldy–Venugopalan
Select a Formulation — Rate coefficient, TTT diagram data, or Parameterized TTT diagram.
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For Rate coefficient, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Reference rate .
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For TTT diagram data, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Relative phase fraction X1, and the Transformation time t1.
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For Parameterized TTT diagram, select an Equilibrium phase fraction from the list. For User defined, specify an expression for . Specify the Relative phase fraction X1. In the TTT Curve 1 section, specify the transformation times tL, tN, and tU corresponding to points on the lower part, the “nose”, and the upper part of the TTT curve at the relative phase fraction X1. Specify the corresponding transformation temperatures TL, TN, and TU, and the TTT curve shape parameters qNL and qNU.
The rate term can be modified from its original form. If applicable, select Include retardation term, and specify the Retardation coefficient Cr. If applicable, select Define temperature limits, and select the Lower temperature limit Tl and the Upper temperature limit Tu from the respective lists. For the User defined options, specify, respectively, expressions for Tl and Tu.
Koistinen–Marburger
Select a Formulation — Koistinen–Marburger coefficient or Martensite finish temperature.
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For Koistinen–Marburger coefficient, specify the Martensite start temperature Ms and the Koistinen–Marburger coefficient β.
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For Martensite finish temperature, specify the Martensite start temperature Ms and the Martensite finish temperature M90.
Hyperbolic rate
Specify the Hyperbolic rate constant Ps → d and select an Equilibrium phase fraction from the list. For User defined, specify an expression for . If applicable, select Define temperature limits, and select the Lower temperature limit Tl and the Upper temperature limit Tu from the respective lists. For the User defined options, specify, respectively, expressions for Tl and Tu.
User defined
Specify the Phase transformation contribution As → d. The expression defines the rate at which the destination phase forms, at the expense of the source phase.
If applicable, select Define temperature limits, and select the Lower temperature limit Tl and the Upper temperature limit Tu from the respective lists. For the User defined options, specify, respectively, expressions for Tl and Tu.
Phase Transformation Latent Heat
This section is active if you have selected Enable phase transformation latent heat at the physics interface level. You can specify the latent heat ΔHs → d that is released during the phase transformation.
Phase Transformation Strain
The Transformation induced plasticity check box is available if you have selected Enable transformation induced plasticity at the physics interface level. In case of transformation induced plasticity, specify the Transformation induced plasticity parameter and the Saturation function Φ.
The Plastic recovery for destination phase check box is available if the Enable thermal strains has been selected at the physics interface level. If you have selected Plastic recovery for destination phase, you can specify the Plastic memory coefficient Θs → d. The default value is zero, which means that no plastic straining in the source phase will be carried over to the destination phase.
If you have selected Parameterized TTT Diagram or Parameterized TTT Diagram, Fixed Exponent, you can visualize the TTT curve corresponding to the entered parameters in the TTT curve 1 or TTT Curve 2 sections.
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Make a preview plot by selecting TTT curve preview.
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Generate a plot by selecting Create TTT curve plot.
Advanced
Numerical smoothing can be applied at temperatures that correspond to a sudden activation or deactivation of the phase transformation. If you select Advanced Physics Options, the Advanced section is used to assign smoothing:
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Transformation temperature smoothing, ΔT, in case you have used Define temperature limits.
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Martensite start temperature smoothing, ΔMs, in the case of the Koistinen–Marburger phase transformation model.
The smoothing parameters ΔT and ΔMs each defines a temperature span across which the phase transformation rate term is smoothly ramped. In the limit of a zero smoothing parameter value, the ramping reduces to a Heaviside step function.