The trend towards lightweight construction has helped materials such as aluminium and plastic to become established in the automotive industry, and they will remain legitimate alternatives to steel during the shift from the combustion engine to the electric motor. Even so, in the growing global industrial sector of electromobility, demand for steel is predicted to remain high or even to increase.
This is the conclusion of a study by the German Handelsblatt Research Institute (HRI), commissioned by voestalpine. The development of innovative high and ultra high-tensile steel grades also secures the long-term future of steel in the automotive industry, because not only is the material both lightweight and tough, it is also easy to process, can be recycled, and is cost-efficient. Therefore, with its unique combination of materials expertise and processing competence, the technology group voestalpine is also excellently equipped to meet the future demands of the automotive industry, while with its comprehensive expertise it can actively help shape the future of electromobility.
Tomorrow’s electromobility will feature an ‘intelligent materials mix’ in which steel plays a crucial role. That is the conclusion of a study into the role of steel in electromobility, which was presented during the 2019 Handelsblatt Annual Conference in Düsseldorf on the future of steel. The trend in electric vehicle development of reducing weight at any price is now over. The carbon-fibre reinforced plastics, in particular, which are lighter and tougher, but also significantly more expensive than steel, appear to be losing ground in this area. The reasons behind this shift are the costs and the difficulty of recycling carbon compared to steel on the one hand, and the permanent innovations in steel toughness and weight on the other.
Share of high strength steels in vehicle construction grows to 30%
According to the study, BMW, for example, will be constructing its model i5 in steel and light alloys from 2021, rather than using carbon which dominated in the i3. Tesla, too, is reducing the share of aluminium and titanium in its model 3 in favour of steel. The European steel industry is now able to supply ultra high-tensile yet light and formable steels. They score with their ease of processing, the homogenous surface for painting, higher raw material availability, and their ability to be combined with other materials.
“The share of high strength steels amongst the steel grades used in vehicle construction will rise from its current level of 18% to 30%,” says Jan Kleibrink of the Handelsblatt Research Institute, citing preliminary work by the Posco Research Institute. According to the World Steel Association (worldsteel), this would allow vehicle weights to be reduced by between 25% and 39%, leading to potential savings of 3 tonnes to 4.5 tonnes of greenhouse gas emissions over a vehicle’s service life. Rather than disproportionately expensive weight reduction, the trend is now towards achieving a balance between weight and costs by using a mix of different steel grades with aluminium and plastic surfaces.
Irrespective of the material used, absolute priority is given to the safety of a car body in the event of an accident. That’s why, to date, a combination of aluminium and steel has been used. New steel grades have 3 to 4 times the tensile strength of conventional steels, making them particularly suitable for use in safety relevant areas, as the study shows. voestalpine is regarded as a technology leader in the production of ultra high strength yet increasingly lightweight body parts which ensure passenger safety while helping to significantly extend the electric vehicle range by reducing the overall weight.
Steel components in the electric motor and drive
The HRI study examined the choice of materials in the electric motor as well. The outcome is that steel also plays a crucial role in the motor and drive. Between 40kg and 100kg of so called non-grain-oriented electrical steel are used in the construction of a purely electric vehicle. That could increa