Multiple Adiabatic Shear Fragmentation and Microstructure Evolution of Explosive-Driven TA2 Pure Titanium Cylinders

The fragmentation experiments of TA2 industrial pure titanium cylindrical under different explosion pressures were carried out. Through the analysis of macroscopic microscopic and fracture for the recovered fragments, the fracture mode and mechanism of explosively fragmentation of TA2 metal were discussed. The results show that though the fracture modes of TA2 cylinder are all shear fracture in explosive-driven cylinders expansion tests, the failure mechanism of shear mode is different for tests under different explosion pressures. It is observed that the shear failure is caused by the evolution of micro-voids in tests under relatively low pressure but controlled by multiple adiabatic shear under the higher explosion pressure. The microscopic metallography shows that the dynamic phase transition of alpha ->beta may occur during the high-speed deformation of the TA2. It is shown that the microstructure of the inner surface is converted to lath martensitic with a specific orientation and the grain size is apparently larger than the as-received grain size. Thus, it is necessary to consider the influence of the dynamic phase transition of material under the action of the shock waves when analyzing the fracture characteristics and mechanism of external explosive experiments. This work can provide a significant reference to the analysis of multiple failure modes of cylinders under external explosion loading conditions.