Heat treating is the controlled application of time, temperature and atmosphere to produce a predictable change in the microstructure of a material to achieve desired material properties. However, alloys are complex systems where the microstructure and properties depend on both the processing conditions and chemical composition. Variations in heat-to-heat composition, particularly in terms of minor elements, or the extent of inhomogeneity arising from solidification affect properties and processing windows. When these data are not available, Thermo-Calc can be used to fill the gaps and make predictions of material behavior throughout the material’s life cycle as a function of composition, temperature and time.

## Predict a Wide Range of Materials Property Data

*Thermophysical properties: *Specific heat, enthalpy, heat capacity, heat of formation, density, coefficient of thermal expansion, viscosity (of liquid), surface tension (of liquid), interfacial energy, thermal conductivity and electric resistivity

*Kinetic properties:* Diffusion coefficients, atomic mobility

*Mechanical properties:* Yield strength, hardness

*Properties related to equilibrium and non-equilibrium solidification:* Liquidus, solidus, incipient melt temperatures, freezing range, fraction solid curves, solidification path, fraction eutectic, microsegregation, partition coefficients, latent heat, shrinkage, susceptibility to hot tearing and more

*Properties specific to steel:* A1 and A3 temperatures, martensite start temperature, martensite fractions, and kinetics of pearlite and bainite formation.

## Gain Insight into Materials Processing

Thermo-Calc can simulate the effects of different types of heat treatment – such as homogenization, aging, quenching, surface hardening, stress relief and post-weld heat treatment – to predict the phases/microstructure that form.

*Solidification and homogenization*

- Determine homogenization temperature
- Predict time needed to homogenize

*Aging and precipitation*

- Generate TTT diagrams for specific chemistries
- Determine solvus temperatures of precipitates (i.e., gamma prime)
- Predict critical phase transformation temperatures (i.e., beta transus, A1, A3)
- Calculate precipitate volume fraction and size distribution as a function of time
- Predict stable/metastable precipitation

*Surface hardening*

- Calculating furnace activities and chemical potentials based on gas ratios
- Predict case-depth profiles and precipitate formation during carburization, nitridation, carbonitriding
- Determine type and amount of carbides