Effect of tempering temperature on expansion and fracture mechanism of 40CrMnSiB steel cylinder shell

The study on the fracture mechanism of steel cylindrical shells under different heat treatment conditions was helpful to understand the dynamic response of metal shell under high strain-rate loading. Therefore, the effect of tempering temperature on the expansion and fracture of metal cylinder shells and the regular pattern of fragmentation mass, size distribution fragments was analyzed by using a high speed photography technique and the recovery experiment of static explosion in well. The results revealed that fracture behavior changed from tensile-shear fracture to shear fracture occurring in a 40CrMnSiB steel cylinder shell internally filled with CL-20 based high explosives with the increasing of tempering temperature, and the different tempering temperature conditions on shell have a marked impact on behavior of fragments mass and size distribution. The radial expansion displacement of 40CrMnSiB steel cylinder shells tempered at 500°C and 600°C was increased by 39.43% and 21.46%, respectively, compared with that of the shell tempered at 350°C. Besides, the fragmentation degree of 40CrMnSiB steel shell decreases and the total number of fragments reduces gradually with increasing tempering temperature, but the fragments numbers which mass was more than 1.0 g increase from 105 to 159 gradually, which was increased by 77.4%, which could be helpful to improve the understanding of influence of material properties on the deformation, expansion and fragmentation of warhead, also could provide a constructive guidance for selecting heat treatment technology of warhead material.