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Lightweight design in the automotive industry is not always combined with the usage of alternative materials like composites. Even high strength steels have high potential for reducing the weight for lightweight design. For the forging industry a new steel is developed, which enables the TRIP-effect (Transformation Induced Plasticity) for forging parts. This material effect is already well known and used for steel sheet structures. The TRIP-effect is based on the structure of the TRIP-material containing retained austenite, which has the possibility to form residual stresses due to the austenite-martensite transformation under cyclic loading. Beside static properties, the dynamic and cyclic material behaviour has a high importance for parts in the automotive industry. So, for lightweight design, a focus has to be on fatigue behaviour under service loads including overloads for an optimal weight reduction.

The steel industry has been offering high-strength steel grades for decades to fulfil various customer demands. Our new approach is a high strength hot-dip galvanized steel aiming at a strength level of about 500 N/mm2. This material combines high corrosion resistance and high-strength with an increased potential for further material gauge reduction and hence weight savings. As an example, the designing, stamping and testing of a complicatedly shaped bumper bar are discussed. This features, specifically, the shape control technique used to overcome springback and sidewall curl effects. These springback effects are the result of an unbalanced bending and unbending process while the sheet metal passes over the draw radius. The appropriate balancing of the forming tools has contributed to an extremely robust stamping process, which is desensitised tremendously against the variation in yield strength.

The benefits of bake-hardening steels for body applications in the automotive industry are well known since several years. These steels offer the potential of weigth savings without major loss of formability. Thus this group of high-strength steels is the first to find broad application for exposed panels. This paper sums up the different concepts of producing cold-rolled electrogalvanized and hot-dip galvanized bake-hardening steels. These concepts are critically discussed from the point of view of stable production. Important aspects for batch annealed or continuously annealed steels are the control of grain size and temper rolling. New hot-dip galvanized bake-hardening steels have been developed; as a result of degassing to ultra low carbon contents in modern vacuum treatment facilities. Beside bake-hardening effects special emphasis is given to the strain-hardening behaviour and to the ageing resistance of bake-hardening steels.