Research On The Expansion And Fracture Mechanism Of Metal Shells Based On Freezing Recovery

Aiming at the expansion and fracture mechanism of metal cylindrical shell under the internal explosion loading,the two-dimensional dynamic response model of metal cylindrical shell under internal explosion loading,the recovery of the shell in different expansion phases and the influence of different tempering temperature on the fracture mechanism of the shell are studied.This research can lay a foundation for furtherly understanding the mechanism of expansion and fracture of metal cylindrical shells and the relationship between macroscopic fracture behavior and microstructure evolution process.Firstly,according to the dynamic response characteristics of the cylindrical shell under internal explosive loading,the theoretical model of the expansion response of the shell under the combined action of the shock wave and detonation product is obtained.Compared with the numerical simulation results,the calculation results are in good agreement.Secondly,an experimental method for recovering shells at different expansion and fracture phases is proposed by using computer simulation technology.The fracture development morphology of the shells in three different expansion and fracture states were obtained by the designed recovery experiments.The shell wreckage of which axial crack almost throughout the entire shell is recovered,and the measured shape and size agree well with the simulation results.Finally,the recovery experiment method was applied to study the effects of different tempering temperature on the dynamic process of expansion and fracture of metal cylindrical shells,and the recovery devices were redesigned.Then,through the recovery experiments,the fracture morphologies of metal cylindrical shells in the four tempered states of 200°C,350°C,500°C and 600°C was obtained.On this basis,the effects of different tempering temperatures on the fracture pattern,crack initiation,propagation and distribution are analyzed,and the influence rule of tempering temperatures on the macroscopic fracture characteristics of cylindrical 40 CrMnSiB steel shells is revealed.The microstructure of the fracture was analyzed by scanning electron microscopy,and the effect of tempering temperature on the micro-fracture characteristics of the shell was studied.