One of important resistance parameters introduced into engineering calculations for selection of materials and evaluation of their operating properties is material crack resistance. Contrary to the stationary fracture toughness K1c, J," the dynamic fracture toughness K,d, J,d, ~ is also an important parameter. In this paper, the authors have evaluated the relation between the parameters of the dynamical fractures toughness and the structure as well as impact resistance in chosen frictionally welded joints. The above-mentioned joints are made of the following steel parts: N9E-45, 18G2A-St3S, St3S-45, 40H-45, 18G2A-40H. In this experiment, the instrumented bending impact test was used.