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FEM modelling of heat treatment process
The finite element method (FEM) can be used to model and simulate heat treatment processes, which
involve heating and cooling of materials to alter their mechanical and physical properties. FEM
provides a powerful tool to analyse and optimize heat treatment processes by predicting temperature
distributions, phase transformations, and residual stresses in the material.

Heat treatment of materials is a fundamental metallurgical process. Materials are subjected to heat
treatment to relieve internal stresses, reduce brittleness and to improve machinability. The properties
of materials can also be altered such as hardness, strength, toughness, and wear resistance to suit
particular applications. Nevertheless, heat treatment can generate unwanted stresses and
deformations, a fact that has to be taken into consideration when designing or changing the sequence
of manufacturing for a given component. One way to decrease cost and reduce time in product
development can be to use simulation tools that can reliably predict the final properties and shape of
a component caused by the used manufacturing process. A decrease in cost and better knowledge of
final properties already in product development can give the company a better market position and
competitiveness.

The objective of heat treatment simulation studies is to establish a predictive theory that would enable
us to predict residual stresses, distortion, and material properties such as microstructure of material
and hardness after a heat treatment process. To be able to improve a heat treatment process it is
important to understand the material behavior and to control the process parameters. One frequently
used numerical method to simulate thermo-mechanical behavior is the Finite Element Method (FEM).

Heat Treatment of Metals
Heat treatment is a collection of many processes such as annealing, stress relief, quenching, tempering,
and ageing. All the different heat treatment processes consist the following three stages 1) heating of
the material, 2) holding the temperature for a time, and 3) cooling, usually to room. However, the
temperature and time for the various processes is dependent on the material mechanism controlling
the wanted effect. For example, if the driving mechanism is diffusional the time must be long enough
to allow any necessary transformation reaction. During heating and cooling, there exist temperature
gradients between the outside and interior portion of the material; their magnitudes depend on the
size and geometry of the workpiece. If the rate of temperature change in the surrounding is too high,
large temperature gradients may develop in the component. This creates internal stresses that may
lead to plastic deformations and even to cracking (Fig. 6. 22).

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