Automakers will stick with steel

In the year 2000, steel will remain the main material worldwide for automobiles, a spokesman for German steel producer Thyssen recently told the annual conference of the International Iron and Steel Institute.

“Steel offers key advantages in meeting demands of the automobile of the future, namely a fully developed manufacturing technique, high surface quality, safety, repair and recyclability, as well as lower materials cost,” Dr.-Ing. Ekkehard D. Schulz said.

Allowing that plastics and aluminum producers have made strides in working with automakers, Dr Schulz believes the principle of a basic body frame in which styling is varied by attaching parts runs counter to the customer’s desire for an individualized vehicle.

German steelmakers have been working closely with automakers on the processing behavior of steels, Dr Schulz said. An industry-wide experimental vehicle program with Porsche, for example, demonstrated how extensive use of high strength steels produced both weight savings and increased safety without changing the existing automobile construction system, he said.

Automation and new production techniques, he said, have set stricter requirements for steel in terms of tolerances, quality consistency and surface properties. In response, steelmakers have developed a range of new steels, use of which can be optimized according to specific parts of the car body.

New grades of cold rolled steels with higher yield points, for example, were developed to provide better ductility and easier forming. Dual phase steels, which change metallurgical structure during forming, have been introduced to provide hardness and tensile strength in addition to ductility. Bake hardened steels, another innovation, are ductile when they are drawn, then are hardened on heating in the automotive paint line. Additionally, micro-alloyed special deep drawing grades, known as IF steels, are increasingly available for extremely demanding drawn components and can be used advantageously with hot-dip galvanized sheet.

Formability of certain grades has been so improved, Dr Schulz said, that several components can now be replaced by a single integral piece. Even complex structural elements can be formed from high strength steels, he said.

In his speech, Dr Schulz also mentioned composites which combine the properties of steel and other materials, including thin steel sheet bonded to fibreglass reinforced plastic for lightness and high paintability in applications such as the automobile roof, and vibration damping laminates with a plastic core for noise reduction.

Additional possibilities to increase cost effectiveness lie in prefabrication of components by the steel supplier, he said. One example is production of automotive floor pans of hot dip galvanized steel by laser welding of steel sheets.