Structure and properties of Cu-37%Zn alloy during quasi-spherical explosive loading

Abstract

The relations between the parameters of loading by powerful convergent shock waves (such as high pressure 40-300 GPa, high-speed deformation 106-107 с-1, tensile stress 0.25-1.75 GPa at unloading and temperature 100-2500°С ) and structural changes (main of which are effects of localized deformation, beta–alpha–beta transformation, the melting and crystallization) in alloy Cu-37%Zn were investi-gated. The investigations were performed with ball samples with diameter 60 and 40 mm. The balls were subjected to the explosion of a spherical explosive charge 10 и 20 mm thick from the surface at twelve points spread uniformly over the charge’s surface. The calculated pressure was 40 и 70 GPa on a ball’s surface and 180 и 300 GPa at its center. A correlation between macrostructural and microstructural changes and the geometrical conditions of shock-wave loading according to various schemes has been found. Effects of the interaction of converging shock waves at loading by and the related phenomena of localization of plastic deformation and the fracture were studied. The initiation of the radial cracks in the spherical samples occurs where the tensile stresses at unloading begin to exceeds the dynamic yield strength of the material. It is determined, that in the spherical sample of brass this distance corresponds to a half of radius of the sample, and the value of the tensile stress is approximately 1.3 GPa, that is close to the spall dynamic strength of brass - 1.75 GPa and exceeds the ultimate static strength of brass by a factor of 5.