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The authors consider the problem of the collision of two metal plates of identical thickness l at velocity v/sub 0/ in a vacuum and in the presence of an intervening layer of air of thickness l/sub 0/. They assume that the length of the plates is much greater than their thicknesses and accordingly study the wave interaction process in the one-dimensional approximation. The experiment used circular polished plates of copper and steel from which a container was prepared and which was placed in a vacuum furnace and heated to 1000/sup 0/C in a vacuum of up to 10 /sup -5/mm Hg. The specimens were then cooled to room temperature. By means of an explosive charge, a projective plate 3.9 mm thick, which accelerated one of the container plates, was projected against the container. The experimental dependence of the thickness of the spall plate on impact velocity is given; when an air gap was created between the colliding plates (nonhermetic container), spalling was not observed. It is determined that the presence of an intervening layer of air aubstantially modifies the wave pattern and spalling develops at one of the free surfaces of the plate.

In order to clarify the question of the effect of the hardness of materials on the position of the lower limit in explosive welding, the authors carried out experiments with materials of essentially different hardnesses. (The investigation of the processes that take place near the lower limit of the region of welding is important in helping us to understand the mechanism of the formation of the welded joint. The experiments permit these conclusions: The process of self-purification in the explosive welding of materials of different hardness can take place as a result of the formation of a flow of material from the softer plate alone; and, in calculating the lower limit of the welding region, the H /SUB V/ of the softer material should be substituted in the expression for calculating the critical angle..gamma.. *.

This paper focuses on the effects of shock waves on the electromagnetic characteristics particularly sensitive to structural changes in ferromagnetic: the higher harmonics in the signal from the secondary emf and the Barkhausen noise signal, which together provide a method of forecasting the mechanical parameters of St. 60 components in explosive working. Control specimens of St. 60 of size 8 X 8 X 100 mm and ones treated with shock waves were tested on an RM-102 tensile tester in accordance with GOST 1497-73, and also on an impact tester to determine the mechanical properties. Some of the specimens were also submitted for metallographic analysis. The authors conclude that mechanicalproperty forecasting for steels by nondestructive methods can be based on measuring the Barkhausen noise, this being the method most sensitive to the structure change in steel produced by shock waves.