For making an alloy design for rail steel I am looking for software that can be used to generate the CCT and TTT diagrams and predict the material properties. Came across ThermoCalc as a software, but unable to gather information whether it can be used to make CCT diagrams of Steel Alloys. Looking for answer from researchers who have experience in this field
Thermocalc alone cant give you TTT or CCT for an alloy.... Dictra (thermocalc + diffusion kinetics incorporated) or TC PRISMA software are generally used for extract those phase transformation kinetics information....
Thermo Calc plus CFD can provide an outline of the changes of phases. TC PRISM and Dictra, that would be the best
Themocacalc plus CFD would give you some idea of phase changes, some basic dynamics of the flux crystallization, but RC PRISMA and DICTRA give the complete picture.
Could use this - http://calculations.ewi.org/vjp/secure/TTTCCTPlots.asp
But it depends how highly alloyed your steel is
Try
https://steelnavigator.ovako.com/steel-navigator/heat-treatment
Hi Rajeev Kumar Singh ,
Thermo-Calc is for forming thermodynamic calculations (Phase prediction/ Scheil solidification etc.). While for Calculation of CCT/ TTT diagram, Kinetic/ mobility data is required. ThermoCalc in conjunction with TC-Prisma/Dictra modules which use mobility and diffusion data can help in probing into the phase transformation behavior and kinetic aspect.
Hope this will be of help.
Regards,
GM
ThermoCalc works on the thermodynamic database and relies wholly upon metallurgical thermodynamics. For the calculation of CCT or TTT diagram, one must have a tool considering kinetic energy as well for any transformation or precipitation reaction. You can say if ThermoCalc does not tell a phase to be formed it won't form, but if it says yes then kinetics is the deciding factor whether that phase will form or not. You can try with the phase fraction diagram and decide the temperature which you are getting your desired phase fraction at. Like others said Prisma (only for precipitation study) or Dictra are some modules by ThermoCalc. But you have to buy these modules separately to get started and these are not cheap. I personally attended a course offered by Prof. K. C. Hari Kumar at IIT Chennai. Dictra is not easy and requires coding (and needs a lot of practice too). Gleeble or Dilatometry is the best to simulate the process, however, it necessitates large sample volume, time, and effort. I used a software called JMatPro (which is again a paid one) to calculate the precipitation kinetics in duplex stainless steel and it performed well. However, the database is not as comprehensive as Dictra's. Another option is a free fortran code made by Prof. H. K. D. H. Bhadeshia available online (link: https://www.phase-trans.msm.cam.ac.uk/map/steel/programs/mucg83.html) where you can predict TTT by providing the chemical composition.
Thermo-Calc is a software that minimizes the Gibbs energy allowing the calculation of phase diagrams. It requires thermodynamic CALPHAD type databases that contain the Gibbs energy of all phases in function of temperature and composition to do so. It has a Diffusion Add-On Modules to calculate multicomponent Diffusion including concurrent phase transformation (DICTRA = DIffusionControlledTRAnsformation) and the Precipitation Calculation Module (PRISMA) to calculate Nucleation and Growth of precipitates. Both these modules require an additional Mobility Database to run. (and no: DICTRA does NOT require scripting, it can be easily set up in the Graphical User Interface).
TTT and CCT (only available in the latest release of Thermo-Calc) Diagrams for steels can be calculated using Thermo-Calc's Steel Model Library. The model currently includes martensite, pearlite and bainite growth. The pearlite model is described here: Article Pearlite in Multicomponent Steels: Phenomenological Steady-S...
The martenstite model is based on these publications:
https://link.springer.com/article/10.1007%2Fs11669-018-0660-1
and
Article Thermodynamically Based Prediction of the Martensite Start T...
A publication on the bainite model is currently in preparation.
Sometimes "TTT Diagram" also means what we would call a time-temperature-precipitation (so TTP) diagram. Such a diagram describes the growth of any precipitate in any matrix phase (could be for example the growth of MC carbide in austenite, but could also be the growth of Gamma' in a Gamma Matrix of a Nickel Superalloy, or growth of Theta phase in FCC Al matrix. Such diagrams can be calculated in Thermo-Calc using the Precipitation Add-On Module.
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