As a result of the electromobility trend, the demands placed on modern automotive lightweight construction are having an impact on material selection. With its consistent focus on research and development, and the networking of material and processing expertise across the Group, voestalpine is developing new material concepts on an ongoing basis.
Lightweight construction has been a key consideration in automotive manufacturing for over 20 years. The focus lies on achieving the optimum balance between vehicle weight and engine performance. Lighter components lower the vehicle weight, which in turn reduces the necessary drive power, and allow electric vehicles to run on smaller batteries—or to retain battery size but benefit from extended vehicle range. Consequently, there is demand for materials which weigh less while offering at least the same level of function, especially for safety-relevant components. That makes lightweight construction a key consideration in the automotive industry, both as a means of increasing the efficiency of conventionally powered vehicles and for electromobility.
Lightweight material combinations
One approach is multi-material solutions in which a variety of materials are optimally combined according to their properties. Such hybrid materials can combine the strength of steel with the lightness of another material, for example. Now, thanks to the production expertise of voestalpine specialists, one such combination is finding its way into vehicles designed for series production:
"To date the high-tech synthesis of high-strength steel and long-fiber-reinforced plastic has required several steps, as both plastic and metal had to be formed prior to being joined. Now we can form and combine in a single process step—a groundbreaking, cost-reducing achievement."
A hybrid part of this type has the same rigidity as a pure steel part whilst being 30% lighter.
Less than a decade ago, voestalpine introduced the steel-aluminium blank to the market, an innovation which demonstrated the potential offered by steel-based composites.
Share of high-strength steels growing
As a material, steel itself is constantly opening up new options in lightweight construction. According to the Handelsblatt Research Institute study commissioned by voestalpine into the role of steel in electromobility, of all the steel used in vehicle production, the proportion of high-strength steels will grow from its current level of 18 percent to 30 percent.
Researchers at voestalpine Stahl GmbH are also driving this trend with their materials expertise. AHSS, or Advanced High-Strength Steel, plays a key role in this field. For example, as their name suggests, dual and complex phase steels consist of different phases, i.e., tiny crystal lattices which can be created within the steel by means of targeted heat treatments. They give the material high and ultra-high levels of strength.
voestalpine high-ductility steels
“We have further improved conventional AHSS through changes to the microstructure design: in addition to extreme toughness and an excellent crash performance, the HD (High Ductility) versions have much better forming properties,” says Thomas Hebesberger, Head of Research at voestalpine Stahl GmbH, presenting these advances. This makes AHSS HD steels particularly suited to meeting the demands of vehicle manufacturers. “In order to better satisfy the demands of our automotive customers, one of our research focuses lies in improving the weldability of our AHSS high-ductility,” says Hebesberger, highlighting current developments.
Taken together, improved steel materials with strengths of up to 1,800 megapascals and the relevant advanced joining processes offer improved crash performance. But it’s not only these properties which are likely to please drivers; they also contribute to lowering vehicle costs, and improving recyclability.
Cost efficiency as a factor
All over the world, OEMs are looking for more lightweight construction solutions. Yet because of cost, aluminium, magnesium, titanium, and carbon-fiber-reinforced plastics (CFK) are usually limited to special edition models. But even here manufacturers are reconsidering: BMW, for example, will be constructing its model i5 in steel and light alloys from 2021, rather than using carbon as in the i3. With its innovative material concepts, voestalpine is excellently positioned to serve the dynamic automotive industry market.