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Taking steps towards lighter cars

Published: 15 April 2020

Requirements for lighter and stronger materials in the automotive industry opens the way for aluminum – though there are still problems in the hot forming process. Justine Decrozant-Triquenaux has brought science closer to a solution in her licentiate thesis.

In the process of electrification of cars, the issue of heavy structures becomes more and more relevant. Batteries are heavy and high weight makes them less effective. To compensate, a steady struggle to reduce weight throughout the design is fought.

"Like chewing gum"

Vehicle parts, including bearing beams, have traditionally consisted of hot pressed steel. Now that the industry wants to reduce weight and thus switch to aluminum alloys with high strength, other problems emerge. – When heating aluminum to the temperatures required for hot pressing, it becomes like chewing gum; it just sticks to everything in contact. Aluminum adheres to the tools used in hot stamping, which causes problems, says Justine Decrozant-Triquenaux. When the aluminum attaches to the pressing tools, the pressed mold geometry and tolerances gradually changes. To avoid it, time-consuming and expensive maintenance is required. – Today the production rate is so high, stopping for cleaning to the extent required is simply not possible, it will be too expensive, says Justine Decrozant-Triquenaux.

Lubricant and coating

To reduce the amount of aluminum that attaches to the press tools, Justine Decrozant-Triquenaux has investigated various lubricants in combination with surface coatings. The experiments were carried out so that a small cylinder of the same material type as the pressing tools was rubbed against an aluminum piece, then the cylinder was analyzed to see how much aluminum was attached to it. – The lubricants we thought would not work at all in the high temperatures in question has proved to give very low friction and prevented adhesion, which was very interesting. It has also been found that surface roughness plays a big role, it must neither be too smooth nor too uneven, says Justine Decrozant-Triquenaux.

Work continues

The industry has already shown interest to Justine Decrozant-Triquenaux's research, and now she is looking forward to continuing as a doctoral student in the same subject. In the next phase, she will leave the experimental stage behind, moving in to more real-life tests. – The licentiate is a small step on a long journey and the feeling of being done with something is rewarding. Now it will be interesting to continue, says Justine Decrozant-Triquenaux. If everything goes as planned, she hopes to finish her doctoral studies by the end of 2021.