Effect Of Different Heat Treatment On The Properties And Fragment Formation Of Projectile Materials

The process of weapon structure exploit its performance in use is also the process of the structure damage, destruction, details of structure response in this process is directly related to operational performace of the weapons. Therefore, research on the expansion and fracture mechanism of destruction and fragmentation warhead under high explosive is necessary, find the influence discipline of the projectile material structural response such microscopic structure and macroscopic property fragment formed, provide theory and technology support for the design of missile in military application.Firstly, use the numerical simulation method, research the influence of the different heat treatment on mechanical property, composition of metal microstructure, establish the tempering equation, get the relate between the tempering time, tempering temperature and yield strength. Then, through use high speed camera, the process of different heat treatment shell case expand fracture under high explosive is researched, calculate the energy distribution at the fracture moment, establish the fragment velocity formula which consider the yield strength and aspect ratio of warhead, the result is coincide with experiment’s.Finally, through the fragment recovery well test, the regular pattern of fragmentation mass distribution of different heat treatment shell case is researched, obtain the mott distribution consider the fracture toughness base on the test data, select the typical fragment, use the devices such as SEM analysis the different microstructure that obtained from different heat treatment influence on the shell case’s fracture mechanism. The research shown that, with the tempering temperature increasing, the mechanical properties of 40CrMnSiB and 50SiMnVB changes, strength become lower and toughness increased, the shell cases fracture mechanism under high explosive changes from cleavage fracture to quasi-cleavage fracture, fracture mode changes from tensile shear mixing fracture to shear fracture, tensile crack and shear crack interweaved, expanded, result in the broken of shell case, as the tempering temperature increase, the nucleation time of shear crack in shell case gradually advanced compare to tensile cracks.