INFLUENCE OF STRAIN-RATE ON DUCTILITY OF METALLIC MATERIALS

The flow behaviour of iron and steel X 2 CrNiMo 18 10 is studied in im pact tension tests with strain rates between 1000 and 7000 s(-1) on sm ooth specimens and on notched bars. The neck formation is discussed on the basis of the theory of imperfections. The temperature increase du ring the adiabatic process promotes deformation localisation and insta bility. However, the stabilising effect of the strain rate sensitivity is dominating and leads to an increase in ductility. On the other han d, increased strain rates reduce the local fracture strain leading to an increased dynamic notch sensitivity. Through combination of experim ent and simulation, the location of void initiation could be estimated and the influence of strain rate on the local failure strain could be determined.