The paper analyses the influence of strain rate on the behaviour of un-alloyed steels with R(e) (yield strength) in the range of 210 ... 550 MPa in the deformation process. It analyses the results of the influence of strain rate ranging from 10(-3) to 2,5.10(2) s(-1) on the yield strength, the ultimate tensile strength (R(m)), the elongation (A) and the reduction of area (Z). Achieved results of strain rate in relationship on values of Erichsen number I(E) are also given. By increasing of strain rate ranging from 10(-3) to 2,5.10(2) s(-1) the ratio R(e)/R(m) is increased, whereas it was observed more intensively for steels with the lower value of R(e). By increasing of strain rate up to 1 s(-1) are I(E) values of tested steels increased, whereas the ratio R(e)/R(m) was equal 0,82. After exceeding of this strain rate was the ratio R(e)/R(m) increased and I(E) value is remarkable decreased.
