Steel Model Library

The Steel Model Library is available starting with Thermo-Calc 2019a. It includes martensite and pearlite models designed to help experts working in the steel industry to quickly and easily set up calculations using the Property Model Calculator.

The pre-built steel models currently include the Martensite Fractions, Martensite Temperatures and Pearlite models. A bainite model will also soon be available.  

The Steel Model Library is available for free to all users who have, or upgrade to, the thermodynamic (TCFE9) and mobility (MOBFE4) steel databases plus have a valid Maintenance and Support Subscription. 

Martensite Fractions Model 

The Martensite Fractions property model calculates fraction of athermal martensite based on an analytical equation derived in Huyan et al. (2016). It is assumed that the first forming martensite morphology is the only forming one. The first morphology is determined based on the Ms-temperatures of all morphologies.

See below for more information about the example (PM_Fe_01) demonstrating this model.

PM Fe 01 Transcurve 600Px
The transformation curves plot showing Fe-Cr-C martensite with intercritical annealing.
 

Martensite Temperatures Model 

The Martensite Temperatures property model calculates the martensite start temperature (Ms) based on modeling the transformation barrier with fitted analytical equations. The model is based on Stormvinter et al. (2012) with subsequent update and extension by Gulapura Hanumantharaju (2018) and Thermo-Calc internal assessment. The partitionless equilibrium temperature T0 is calculated using the thermodynamic database. The model also gives temperatures corresponding to 50%, 90%, and 99% transformations. Martensite fractions are calculated with the same algorithm as in the Martensite Fractions property model.

See below for more information about the examples (PM_Fe_01 and PM_Fe_02) demonstrating this model.

PM Fe 02 600Px 
A diagram showing all the Ms temperatures of different types of martensite morphologies (lath, plate and epsilon (hcp)) compared with experimental epsilon Ms values.
 

Pearlite Model

The Pearlite property model describes the thermodynamics and kinetics of pearlite formation from austenite during isothermal heat treatment. It is assumed that the overall composition of pearlite is the same as the austenite composition (system composition), and growth rate is constant over time. Growth rate and lamellar spacing of pearlite are determined by a criterion where either growth rate or Gibbs energy dissipation rate is maximized. The model considers Gibbs energy dissipation due to formation of ferrite-cementite interface in pearlite, finite austenite-pearlite interfacial mobility, solute drag, and diffusion of elements within austenite and along austenite-pearlite interface.

See below for more information about the example (PM_Fe_03) demonstrating this model.

PM Fe 03 TTT 400Px
The TTT (time-temperature-transformation) diagram showing times of start (2% transformation) and finish (98% transformation) as functions of isothermal heat treating temperature in an Fe-0.69C-1.80Mn alloy (mass %). 
 

Steel Model Examples Available in Thermo-Calc

The Steel Model Library includes examples to help get you started. These particular examples are available from within the software starting with Thermo-Calc 2019a: From the menu, choose Help > Example Files > Property models > Steel

  • PM_Fe_01: Fe-Cr-C Martensite with Intercritical Annealing: The example shows how to calculate martensite fractions and martensite temperatures (martensite start, Ms, and 90% transformation temperature M90). The example also shows how Cr content in the alloy influences Ms and M90 after intercritical annealing.
  • PM_Fe_02: Fe-Mn Martensite Morphologies: The example uses the Property Model Calculator with the Martensite Temperatures model. It shows the Ms temperatures of different types of martensites: lath, plate, and ε (hcp), compared with experimental ε Ms values.
  • PM_Fe_03: Fe-C-Mn Pearlite: The example shows how to calculate pearlite growth rate, lamellar spacing, and times of start (2% transformation) and finish (98% transformation) as functions of isothermal heat treating temperature in an Fe-0.69C-1.80Mn alloy (mass %). 

Tip! Search the Thermo-Calc Help
You can find more information about the examples and property models (and all the Thermo-Calc features) in the Help, which is also available with DEMO and Academic versions of the software.

From within Thermo-Calc, press F1 or from the menu select Help > Online Help and then search for Property Model Calculator or any other search term relevant to your query.  

Steel Models References

  1. Huyan, F., P. Hedström, L. Höglund, and A. Borgenstam. 2016. “A Thermodynamic-Based Model to Predict the Fraction of Martensite in Steels.” Met. Mat. Trans. A, 47 (9): 4404–10.
  2. Gulapura Hanumantharaju, A. K. 2018. "Thermodynamic Modelling of Martensite Start Temperature in Commercial Steels". Master's Thesis, KTH Royal Institute of Technology, Sweden.
  3. Stormvinter, A., A. Borgenstam, and J. Ågren. 2012. “Thermodynamically Based Prediction of the Martensite Start Temperature for Commercial Steels.” Met. Mat. Trans. A, A 43 (10): 3870–79. 

Learn More About

How To Get the Steel Model Library

The Steel Model Library is available for free to all users who have, or upgrade to, the thermodynamic (TCFE9) and mobility (MOBFE4) steel databases plus have a valid Maintenance and Support Subscription. 

Thermo-Calc Software is also developing Property Model Libraries for nickel, aluminium and titanium-based alloys. A bainite model is also soon available with the Steel Model Library.

Fill out the form belowy to find out more about the Steel Model Library or to inquire about getting a license.