Electric car charging

Lightweight solutions for vehicles

Joanne McIntyre - 27 April 2017

Scientists from the renowned Fraunhofer Institute for Laser Technology (ILT) in Germany are working with material experts to develop future-oriented stainless steel solutions for the automotive industry.

About the author

Mrs Joanne McIntyre
Joanne McIntyre is the Editor in Chief of Stainless Steel World magazine, and Conference Coordinator for the Duplex Seminar & Summit.
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The latest innovation is a new battery pack that is specifically designed for electric vehicles. The battery pack combines several lightweight engineering technologies as well as new types of cooling and structural strategies.

The Forta H1000 austenitic, ultra-high-strength stainless steel from Outokumpu enables the implementation of structural lightweight engineering initiatives, while providing a high level of safety. Says Stefan Lindner, Senior Technical Manager for Automotive segment at Outokumpu: “A high capacity for energy absorption and increased stiffness with thinner wall thicknesses are crucial characteristics for the development of future lightweight designs in automotive engineering.” Because the batteries for electric vehicles are mainly installed in the underfloor area, their casings have very high requirements in terms of hardness and crash safety.

Batteries for electric vehicles have very high requirements in terms of hardness and crash safety Photo © Outokumpu

At the same time, the structures have to be as lightweight and compact as possible, which is where conventional materials such as aluminum and carbon steels reach their limits. “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 a weight reduction of about 20 percent,” comments Paul Heinen, Head of the FSEM II Project at the Aachenbased Fraunhofer Institute for Laser Technology ILT. 

Light weight and a good formability are crucial elements for vehicle seating components. Photo © Outokumpu

Light weight, formable seating components The Swedish manufacturer is also working with ILT to develop solutions for vehicle seats in conventional vehicles. Light weight and a good formability are crucial elements for the highly complex structural components of the vehicle seats.

Apart from being lighter than conventional materials, the company’s Forta H-series stainless steel products have the added benefit they absorb the impact energy making them safer for the passenger. Lighter weight and stronger materials also result in lower CO2 emissions. However the features most relevant for the design of vehicle seating include the realization of complex component geometries, suitability for welding and the options for thinner components.

Claire Heidecker, Senior Technical Manager, Outokumpu, explains: “Forta H-Series components weigh up to 50 percent less compared to parts made from deep-drawn steels. The material raises vehicle safety through the Twinning Induced Plasticity (TWIP) steel deformation mechanism. Twinning hardens the possible weak points of the component, such as welded areas. In the event of a crash they achieve the mechanical properties of the base material. This means that the Series can be hardened to a tensile strength of up to 2000 MPa. The material dissipates a substantial amount of impact energy in the process.”

Typical vehicle applications are crash-relevant structural parts such as B-pillars, crash boxes, tunnels or seat cross members. Forta H-Series is also suitable for demanding formed parts with reduced wall thicknesses and component integration – such as wheel arches and integrated seat frames.

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