Outokumpu and Fraunhofer ILT work together on lightweight solutions for electric vehicles

The battery pack combines several lightweight engineering technologies as well as new types of cooling and structural strategies. Outokumpu supported the project with the ultra-high-strength stainless steel material Forta H1000 for lightweight construction and crash safety.

Lightweight and safety for future electric vehicles
“A high capacity for energy absorption and increased stiffness with thinner wall thicknesses are crucial for automotive lightweight designs. The Forta H-series fulfills these requirements,” explains Stefan Lindner, Senior Technical Manager for Automotive segment at Outokumpu.

“Our stainless steel ensures an improved crash performance thanks to its special composition. In terms of direct lightweight design, Forta H1000 allows complex components paired with reduced wall thickness. In addition, the H-series can facilitate thinning down of neighboring components. These properties enable new lightweight potential in vehicle design, especially in the field of electro mobility.”

Battery packs require special material properties
Since batteries for electric vehicles are mainly installed in the underfloor area, their casings not only have to be light and compact, but also need to meet high requirements in terms of hardness and crash safety.

“With Forta H1000, we were able to engineer a safer casing despite its leaner structure and thus save a considerable amount of weight. Using 1.2 mm thick sheets instead of 1.5 mm wall thickness allows reducing weight about 20%,” comments Dipl.-Ing. Paul Heinen, Head of the FSEM II Project at Fraunhofer ILT.

A special modular framework with integrated stiffening panels ensures easy access to the components. The stainless steel elements were welded in a penetration-welding process with CO2 laser beams. Internal stress and warpage were reduced through careful configuration of the joints, meaning that only localized annealing is required post-welding.