To use designed materials for automotive steel sheet applications effectively, e.f., collision-absorption components, the detailed information of dynamic deformation should be obtained. This is because automotive steel sheets require high resistance to impact energy upon vehicle collision as well as high strength and fracture toughness for sustaining sufficient structural stability. However, phenomena under dynamic loading conditions are hardly investigated.
Accurate evaluation should also be performed on how safe the steel sheets are under worst conditions like vehicle collision. In vehicle-collision tests, actual vehicles are generally used, but restrictions remain in applying the evaluation data to the vehicle body safety itself and in styling new car designs. Accordingly, the vehicle body safety data are essentially needed before the evaluation of actual vehicle products.
We conduct dynamic and quasi-static tensile tests under strain rates of about 3000 /s and 0.001/sec using a split Hopkinson tensile bar and a universal testing machine, respectively. Detailed deformation mechanisms are examined by analyzing how the quasi-static deformation mechanisms vary under the dynamic loading. Finally, we correlate them with the microstructural evolution processes.