DYNAMIC DUCTILITY OF METALS

The influence of strain rate on the stress strain curve of the impact tension test is discussed on the basis of the theory of imperfections. The temperature increase during the adiabatic process promotes deform ation localisation and instability. However, the stabilising effect of the strain rate sensitivity is dominating and leads to an increase of ductility with increasing strain rate similar to the super-plastic be haviour. On the other hand, increased strain rates reduce the local fr acture strain leading to an increased dynamic notch sensitivity.