Abstract: To understand the influence of tempering temperature on the dynamic process of expansion and fracture of cylindrical metal shell, a recovery experiment is designed to recover the fracture morphologies of metal shells at the intermediate phase of explosion. The 40CrMnSiB steels tempered at 200 ℃, 350 ℃, 500 ℃, and 600 ℃ are used as the research objects. The intermediate states of fractures of cylindrical metal shells at four different tempering temperatures were obtained through the recovery experiment. 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 40CrMnSiB steel shells is revealed. The result shows that, as the tempering temperature is increased from 200 ℃ to 600 ℃, the fracture characteristic parameters of shell are influenced by the improvement in dynamic plasticity and fracture toughness and change significantly at the initial stage; at the later stage, the effect caused by the decrease in the dynamic strength of material is more prominent, so these parameters are essentially constant. The fracture strain of metal shell tempered at 500 ℃ is maximal, which is increased by 48.1% compared with that tempered at 200 ℃. Key

Key words: cylindricalmetalshell, expandingfracture, temperingtemperature, fracturestrain, recoveryexperiment