Local Heat Treatment for Complex Die-Cast Components

Selina Freygang is now pursuing a PhD in the field of die casting. She received the EUROGUSS Talent Award 2026 in January for her master’s thesis, “Innovative Heat Treatment Boosts Performance of Complex Structural Cast Components”, which was carried out in cooperation with Friedrich-Alexander University Erlangen-Nuremberg, the Chair of General Materials Properties, and AUDI AG. The research investigated how complex aluminium die-cast components can be heat-treated in a more targeted manner.

What does receiving the EUROGUSS Talent Award mean to you?

Selina Freygang: The award means a great deal to me and I was particularly pleased to receive it. For me, it is a significant recognition of the work I invested in my master’s thesis. It is especially meaningful because I am now pursuing a PhD and have remained committed to the field of die casting. That gives the award an even greater significance for me and serves as a source of motivation.

Your award-winning work focuses on the heat treatment of complex aluminium die-cast components. What was the central research question?

Selina Freygang: The key question was whether the lightweight potential of a component could be further exploited through an adapted, contour-specific heat treatment. The aim was to improve material properties in a targeted way and ideally achieve higher strength within the component. This would make it possible to reduce wall thicknesses and further decrease overall component weight.

The first step, however, was to achieve a more homogeneous property distribution. Heat-treated components often exhibit local variations in material properties due to differing wall thicknesses. We therefore first wanted to determine whether more uniform properties could be achieved. In the next stage, we pursued a targeted optimisation of material properties tailored to the specific requirements of the component.

What challenge gave rise to this research question, and how does your approach differ from the conventional process?

Selina Freygang: Conventionally, these components are quenched by exposing the entire part to an airflow. The basic heat-treatment sequence remains identical to the state of the art: solution heat treatment, quenching and artificial ageing. The key difference lies in the design of the quenching process.
 

You investigated the process using a shock tower for the Audi Q6 e-tron. Why was this component a suitable case study?

Selina Freygang: The shock tower is a typical die-cast component. It is characterised by a complex geometry and varying wall thicknesses. Geometry plays a crucial role in the developed process because it strongly influences how the quenching acts locally and how effectively material properties can be tailored.

How much effort is required to adapt such a nozzle field to a specific component?

Selina Freygang: If you start from scratch, as I did, adapting the test setup initially requires considerable effort. In my case, it was an iterative process involving a great deal of trial and error. I measured component temperatures during quenching using thermocouples, adjusted the airflow rates accordingly, and then evaluated the resulting mechanical properties. These results then had to be consolidated and assessed. Once the nozzle field has been optimised for a specific component, however, the quenching process can be repeated consistently.

You mentioned that your work went a step further after achieving homogenisation: towards the targeted adjustment of individual component areas.

Selina Freygang: Exactly. Once homogenisation had been successfully achieved, we were able to move on to application-specific tailoring. I referred to this as “Local Tailoring of Mechanical Properties”. Areas relevant for crash performance or requiring high strength could be specifically adjusted through heat treatment.

In other areas, such as joining flanges, higher ductility is required to ensure subsequent joining capability. In those regions, ductility was increased while strength was deliberately reduced. Overall, the heat treatment enables component properties to be adapted to local requirements.

In addition to property tailoring, distortion reduction was an important result. What made this particularly significant?

Selina Freygang: That was actually quite surprising. We were able to reduce distortion significantly and effectively integrate a straightening process into the heat treatment itself. Normally, components have to be straightened after heat treatment, which is both costly and time-consuming.

Distortion occurs as a result of the intensive quenching following solution heat treatment. I utilised the force of the compressed air and was therefore able to work against the direction of distortion. This allowed us to reduce distortion considerably in specific areas – for example, from 0.7 mm to 0.1 mm, or from 0.65 mm to 0.01 mm. These areas were then within the permitted tolerances, potentially reducing the need for a separate straightening operation.

How close is the process to industrial application?

Selina Freygang: At this stage, it was primarily a research project. The results are promising, but further investigations are required before the process can be implemented reliably in an industrial environment.