High strain rate tensile testing of modern car body steels

Abstract

Crash behaviour and light weight have become the major design criteria for car bodies. Modern high strength steels offer appropriate solutions for these demands. The prediction of the crash behaviour in simulation programs requires the information on materials behaviour during dynamic testing. The reduction of the signal waviness and the inertia effects at strain rates above 50s{sup -1} are major issues in dynamic tensile tests. Different techniques for load and strain measurement are compared and evaluated with regard to accuracy and testing effort. Advantages and drawbacks of those various measurement techniques are presented and recommendations for different test purposes are provided. Various modern steels for car body applications have been intensively investigated by high strain rate tensile tests. Significant differences in the materials behaviour could be detected between mild steels and other HSS steel grades like dual phase steels, TRIP, and CP steels with regard to their strain rate and temperature sensitivity. Possible explanations based on microstructural features are discussed. (orig.)