Innovative lightweight construction for the mobility of tomorrow

CO₂ emissions must be reduced. This challenge is also in focus in the automotive industry. To support auto manufacturers on the road to climate neutrality, our colleagues at thyssenkrupp Steel have set themselves the task of developing economical and safe lightweight solutions to reduce CO₂. From design and production processes to the manufacture of innovative materials.

Steel is now the most successful lightweight material in the auto industry. Nine out of ten vehicles in Europe are currently manufactured using a lightweight design dominated by steel. The innovative material is also gaining ground in electrically powered vehicles. In the long term, the material can make a significant contribution to reducing CO₂ emissions.

Cars without steel - it won't work

Steel is the core material of the automotive industry - even in the age of electromobility. Steel is used in drive motors and in the structures of current e-cars and plug-in hybrids. The structure of a current e-car, for example the VW ID.4, weighs around 440 kilograms including the battery box. Doors and flaps weigh another 120 kilograms or so. Since aluminum has no or only a very small weight advantage in the structure, steel is generally preferred here. In addition, all drive motors for electric vehicles require a larger quantity of electrical steel. Depending on the model and whether it is a purely electric car or a plug-in hybrid vehicle - each motor contains between 20 and 90 kilograms of electrical steel, which cannot be replaced by other materials. Thus, the car in our example calculation consists of more than 600 kilograms of steel - and that's just in the basic structure.

Dual-phase steel - lightweight and higher strength

Why steel, and above all lightweight steel, is a preferred material for auto manufacturers becomes clear when looking at CO₂ emissions. Because unlike solutions made from aluminum, lightweight steel is significantly more sustainable and cost-effective.

Dual-phase steels can be used, for example, to produce very thin, lightweight and higher-strength body parts for cars. Significant weight reductions are possible by reducing the thickness. The dual-phase steel DP-K® 290Y490T from thyssenkrupp Steel, for example, makes it possible to produce an outer skin with a thickness of just 0.55 millimeters. A protective layer of hot-dip galvanizing or zinc-magnesium is included.

Hot forming

Furthermore, hot stamping as a leading manufacturing technology offers great potential for cost and weight reduction in automotive construction. Press-hardenable manganese-boron steels (MnB) are particularly suitable for safety-relevant structural components in the auto body due to their high strength combined with good forming properties.

Hot-stamped body components such as the A-pillar, the B-pillar, the longitudinal and cross members and the inner and outer door entry, meet the requirements in terms of weight reduction with the same stiffness, high strength and good dimensional stability as well as improved crash behavior. The MBW-K® 1900 product in particular offers maximum potential for weight reduction. The grade impresses with high deformation resistance in the event of a crash and is used in bumpers, side impact beams or laterally loaded cross members.

Lower emissions thanks to lightweight steel

Although electric cars no longer emit any emissions, the production of an electric car does generate production-related emissions. It is therefore important to consider production-related environmental impact when selecting materials. And this is where new steel concepts for battery housing come out on top. Compared with aluminum-based solutions used today, they produce up to 50 percent less climate-damaging CO₂ at significantly lower cost despite a slight increase in weight. In addition, steel is a very sustainable material that can be recycled while maintaining the same quality.

Clean mobility thanks to CO₂-free steel

However, if the goal of green mobility is to be achieved in the future, it is of course also important for steel to become CO₂-free. thyssenkrupp Steel has developed its own innovative technology for this and set itself ambitious targets. As early as 2030, considerable quantities of CO₂-reduced steel are to be offered and around 30 percent of CO₂ emissions eliminated. By 2045, steel production is to be climate-neutral. One point that is really important is that there are stable framework conditions for these steps, not only here but also worldwide: here, in China, India, Russia, all over the world. Another important point is that environmental protection and zero emissions don't come for free.