Institute for Applied Materials – Materials Science and Engineering

Material Modelling and Process Simulation

Heat Treatment

In the context of the constant further development of heat treatment processes, the multiphysical mechanisms that occur must be mapped with increasing precision. For this purpose, simulation routines developed at the IAM are used to calculate the mechanical, electromagnetic, thermal and metallurgical models as a function of time and temperature and composition. Special focus is put on the description of the resulting microstructural constituents and the resulting component properties. Simulation models serve as the basis for the process design in order to be able to set contour-shaped properties. For this purpose, the institute has models for thermochemical diffusion simulation, metallurgical phase transformation during heating and quenching as well as prediction models for surface states in context of hardness and residual stress profiles. Those models are suitable for further optimization procedures, leading to potential performance increases by optimizing the heat treatment procedure.

The simulation of possible problems ranges from the classical furnace heat treatment with subsequent quenching, through the induction hardening of gears, to the simulative representation of special applications such as the internal quenching system for hardening hard-to-reach regions of components.

We are currently working on the following topics:

Mechanical Surface Treatment

For the process simulation of mechanical surface treatments, a series of dynamic finite element models (FE) has been developed in the department of production and component behaviour, which is continuously maintained and extended. In various projects, the processes shot peening, ultrasonic shot peening and machine hammer peening could be simulated. The general objective of FE simulation of mechanical surface treatments is the prediction of various surface layer characteristics, such as the residual stress state and surface roughness, in order to be able to make statements about the expected component behaviour. However, more specific goals of the simulation of mechanical surface treatments can also concern the prediction of local damage (e.g. by too intensive machining) or of cutting processes (e.g. during abrasive blasting). The suitability of the model and the prediction quality are always checked by combined parameter and sensitivity analyses.

Due to the high dynamics of the processes, the simulations are carried out with explicit equation solvers. The input data are created with the help of Python scripts and allow the fast adaptation of process and model parameters. For the actual simulation the commercially available FE software Abaqus is used. Due to the high strain rates inherent to the process (e.g. in shot peening), special material models must be used to adequately model the material behavior. For this purpose we use viscoplastic material models with combined isotropic-kinematic hardening under consideration of adiabatic heating, such as the consistent viscoplastic material model of Abed & Voyadjis. The calibration of these models is performed with a number of different experiments such as high speed tensile tests, high and low temperature tensile tests and cyclic tests.

We are currently working on the following topic:

Additive Manufacturing

In the department Manufacturing and Component Behavior several finite element models on different size scales are developed and coupled with each other to simulate laser-based additive manufacturing. The primary goal is the prediction of the residual stresses prevailing in additively manufactured components and the resulting component distortions.

In addition, models are being developed to depict the microstructural components that form as a result of the temperature history, in order to be able to describe the resulting component properties.

We are currently working on the following topic: