A model for the dynamic fracture toughness of ductile structural steel

We assume in this paper that the dynamic fracture toughness KId of ductile structural steels is dependent on void nucleation and void growth. The void nucleation-induced dynamic fracture toughness KId·n and the void growth-induced dynamic fracture toughness KId·g were obtained by modifying the void nucleation-induced and void growth-induced static fracture toughness models, respectively, considering the effect of strain rate and local temperature. By the relationship between the void nucleation-induced dynamic fracture toughness KId·n and the void growth-induced dynamic fracture toughness KId·g((KId)2=(KId·n)2+(KId·g)2) dynamic fracture toughness KId could be quantitatively evaluated. With this model the dynamic fracture toughness of two structural steels (X65 and SA440) was assessed, and the causes for the differences between the static and dynamic fracture toughness were also discussed.