VTT recommends special steels for automotive industry

They are also easy to recycle, which reduces the vehicle’s life-cycle costs. Tests show that new steel structures reduce the risk of corrosion, and hence also the cost of superstructure maintenance. The safety requirements can be met at lower weight using these new stainless steels that offer the European automotive industry an enhanced competitive edge.

Tests carried out at VTT and at the Ford Research Center indicate that superstructures made from the new special steels retain their durability in varying, long-term stress situations and offer higher safety in crash collisions than structures made of current materials.

VTT studied and developed new spot welding, adhesive and hybrid joining processes for vehicle superstructure assembly. Using weldbonding, a combination of spot welding and adhesive bonding to join elements made from special steel helps delay the onset of potential corrosion. This also enhances vehicle safety in the long run, and reduces maintenance costs.

Utilization of the new stainless steels for manufacturing vehicle superstructures still requires completion of the development work on product manufacturing methods. Using the new steels will then also be more economically viable.

While the new steels initially yield most benefits when used in heavy-duty vehicles (ships, trains, trucks and buses), all of which have a long service life, they will also be gradually introduced to top-quality passenger cars. Superstructure elements made from the new steels will probably become common within a few years.

VTT’s research showed that these new stainless steels (extra formable austenitic steels) are highly potential to reduce vehicles’ life-cycle costs, since they extend the lifetime of the superstructures and provide them with added durability. They may also be more easily recycled for high-quality raw materials. The introduction of the new steels to other industrial sectors can be awaited in a near future thanks to their good mechanical properties, lower life-cycle costs and applied research on related benefits.

In addition to R&D organisations: VTT, Helsinki University of Technology (TKK) and OCAS belonging to the Arcelor group, the project involved car manufacturers Fiat, Ford, Volvo and PSA. Materials and moulding expertise was provided by steel constructors Outokumpu, Arcelor, Acerinox and Batz.