Mechanism based modelling of tempering

  Simulation tempering Copyright: IWM

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Ali Rajaei © Copyright: IWM

Name

Ali Rajaei

Group Manager Wärmebehandlung

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+49 241 80 99544

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Motivation

Existing thermomechanical-metallurgical models used for the heat treatment simulation consider the basic effects, such as heat transfer, phase transformations, plasticity etc. during the process and allow the determination of residual stresses and the distortion especially after hardening. However, the quantitative prediction is not accurate enough yet to dispense with prototypes and test cycles by the production. Since the functionality and the properties, i.a. residual stresses and material characteristics, of a heat-treated component are essentially determined by the process parameters during tempering, basic mechanisms such as the formation of secondary carbides and the transformation of the retained austenite must be taken into account in order to further improve the predictability of the simulation. Until now the development of properties during tempering is taken into account by suitable material models only scarcely. This aspect, however, is of crucial importance to model the interaction of structural and property changes. Moreover, it is not yet possible to dispense with complex tests for determining the mechanical properties of the material as input parameters for the simulation in order to take account of the property changes during the heat treatment. The modeling of the mechanical properties by physics-based approaches reduces the dependency of the simulation model on the experimental investigations. The quantitative description of the distortion and the residual stress state after the heat treatment enables to decrease the post-machining efforts and to predict the component’s service life.

Goal

  • This study aims at realistic prediction of the evolution of the microstructure, residual stresses and distortion during the entire heat treatment cycle including tempering by means of FE‑modeling and simulation.

Project contents

  • Quantification of microstructure evolution, phase transformations and precipitations, during quenching and tempering by means of dilatometry and Differential Scanning Calorimetry (DSC)
  • Microstructural analysis and characterization of the karbide precipitates by Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM)
  • Investigation of the mechanical behavior, elasto-plastic and visco-plastic effects, during tempering
  • Modelling the exposed themomechanical and metallurgical load collective during the entire heat treatment cycle

Publications

  • Eser, A.; Bezold, A.; Broeckmann, C.; Schruff, I.; Greeb, T. (2014): Tempering-Simulation of a thick-walled Workpiece made of X40CrMoV5-1 Steel. In: HTM 69 (3), S. 127–137. DOI: 10.3139/105.110225.
  • Eser, A.; Broeckmann, C.; Simsir, C.: Multiscale modeling of tempering of AISI H13 hot-work-tool steel – Part 1: Prediction of microstruture evolution and coupling with mechanical properties; Computational Material Science; 113(2015) S. 280-291
  • Eser, A.; Broeckmann, C.; Simsir, C.: Multiscale modeling of tempering of AISI H13 hot-work-tool steel – Part 2: Coupling predicted mechanical properties with FEM simulations; Computational Material Science; 113(2016) S. 292-300
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