EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Electro-magnetic induction heating is a challenge to model, due to the nonlinear nature of the magnetic hysteresis curve and the temperature dependency of this curve and several other electro-physical properties, which lead to a recursive cycle of influence between the electro-magnetic and thermal physics domains. Further intricacies arise once phases and stresses are considered. The heating scheme, transformation kinetics and strain evolution form a stack of dependencies, where it is important to be aware of the underlying assumptions and knock-on effects of errors or inaccuracies throughout the simulation chain. Here it is of great use to have a sample process for which there is a broad variety of data that can be used to verify the process simulation.
This presentation focuses on the local through hardening of a 50CrMo4 steel rod by inductive heating and water quenching. The experiment was conducted on an instrumented scientific induction oven and samples from quenched and tempered rods were analyzed for their planar phase, hardness and stress distributions using metallographic methods and synchrotron HE-XRD. For the simulation, a permeability-linearizing algorithm was implemented to allow for a harmonic-transient leapfrog scheme that would weakly couple electro-magnetic and thermal physics, followed by a mechanical stress simulation of the resulting temperature evolution. The residual stress field was then cut and relaxed to account for the machining of the plate samples from the cylindrical rod. Finally the simulated sample was compared to the real measurements and the accuracy of the model was assessed.