Pequliarities of metal balls deformation by quasi-spherical shock waves

The paper presents results of experimental researches of deformation of balls from Cu, Pb, Ó Ñ-type uranium, aluminum alloys AMg6 and D16, steels St.3, St.10, and stainless steel 12X18H10T with diameter from 55 to 42 mm by quasi-static waves. In the tests the shock waves converging to the ball center were caused by synchronous initiation of the detonation process in the great number of points of a thin spherical layer of heterogeneous solid explosive placed on the ball surface. The final result of shock-wave loading of balls is determined by the level of applied loading (HE layer thickness) and physical-mechanical properties of balls material, among which the yield strength is very important. For the all tested metals the average radius of a cavity, formed in the ball center, grows in progression as thickness of the spherical HE layer increases. With use of sequential increase of HE layer thickness for copper and lead balls continuous initially we recorded the loading regimes corresponding to various extent of damage: saving of material continuity, cavity formation, and ball fragmentation. In comparison with other metals, balls from Cu and Pb save their intactness having abnormally large sizes of cavity. These sizes reach in diameter a half of the same parameter of the ball due to high plastic properties of these metals. For aluminum alloys and steels one can observe influence of anisotropy of mechanical properties on the cavity geometry: the cavity shape is close to ellipsoidal. The paper presents discussion of results of metallographic analysis of the balls material after testing. The analysis results testify to irreversible structural changes in metals. The work was partially supported by RFFI funding (Grant #97-01-00344).