The mechanical characteristic of new developed steel sheets.

The mechanical properties of new thin steel sheets used in automotive industry are the main object of this work. The influence of strain-rate on their mechanical properties has been studied using two methods of testing: tensile testing and impact testing on instrumented Charpy hammer. The tensile test provided known characteristics values such as the tensile strength Rm, the yield stress Rp0,2, the strain hardening exponent n and the flow curve for the uniaxial tensile stress. Behaviour of the material under dynamic load indicates different characteristics with respect to the static ones, and/or quasi-static, respectively. The Charpy instrumented hammer has been used to produce dynamic loading of materials. The dynamic strength RmD, which is used for evaluation of the impact resistance ability of sheet components, was established. Considering the structure sensitivity in plasticity the analytical and experimental expressions for n values of high strength steel sheets were deduced. The deformation of specimens at the level of microstructure has been evaluated after impact testing. The impact test was simulated using the ANSYS software. The deformation of samples after impact testing has been simulated. The dependence of strength on the strain-rate within the range of strain-rate=10-4s-1 to 102s-1 was expressed.Available from STL Prague, CZ / NTK - National Technical LibrarySIGLECZCzech Republi