Heat treatment sintered gear


Ali Rajaei © Copyright: IWM


Ali Rajaei

Manager Research field Heat Treatment


+49 241 80 99544




The powder-metallurgical process chain for the production of gearwheels makes it possible to sustainably reduce the energy, resource and cost expenditure. Investigations show that the load bearing capacity of the pressed and sintered gears can be significantly increased by a subsequent local densification of the functional surfaces. However, the potential of powder metallurgy in gear production has not yet been fully utilized. In the future, comparable gears are to be produced by the conventional method ,because the PM-gears produced so far have a shorter service life. It is an open question as to how the density profile of the surface layer influences the hardening process and thus the load bearing capacity of the gear. The optimum combination of density and hardness profile in terms of load bearing capacity is not yet known. The discovery of the maximum performance through powder metallurgy produced components thus becomes the motivation of this project.

It was developed in cooperation with Research Association for Drive Technology (FVA) and the Machine Tool Laboratory WZL of RWTH Aachen University.


  • To use experimental investigations and numerical simulation as a tool to support the optimization of the process

  • Offer recommendation guidelines for heat treatment/case hardening of PM gears

  • To clarify optimum process control by comparing PM gears manufactured in different ways

Project contents

  • Modelling of carbon diffusion during "carburisation" as a function of porosity

  • Modelling of phase transformations during quenching

  • Investigation of the conversion behaviour as a function of carbon content

  • Prediction of residual stresses after heat treatment

  • Optimize process control parameters by simulating case hardening and predicting microstructure transformation and residual stresses.

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