The Structure and Mechanism of Convergence of a Cylindrical Shell Made of Low Carbon Steel Under Explosive Loading

An experiment was performed on the convergence of a thick-walled cylindrical shell made of steel 20 under the action of an explosion. The explosion was initiated from eight points evenly spaced along the ring on the cylindrical surface of the shell. It is established that convergence begins by a solid-state mechanism, with division into eight fragments according to the number of initiation points. In the process of convergence, the solid-state mechanism is replaced by a hydrodynamic one, in which the shell converges without collapsing, through the formation of ejections (cumulative jets), their expansion and closure in the center of the shell. The change in the convergence mechanism is explained by a decrease in strength and an increase in the ductility of the steel due to an increase in the temperature of the shell during the convergence process. The study of the microstructure showed that high-speed deformation during convergence occurs with the formation of extended bands of localized shear and vortex structures.