Influence of the metal microstructure on the jet formation process

Based on a review of the scientific and technical literature, an analysis is made of the influence of the material’s microstructure of the cumulative lining on the breakdown ability of cumulative charges: depending on the average diameter, strength of the boundaries, uniformity of shape, size and orientation of the grains of the metal. A model of the ideal metal structure of the cumulative cladding is advanced and substantiated. An assessment of the current level of development of technologies for the production of cumulative linings is carried out, promising technologies are considered, the possibility of creating cumulative linings with the required microstructure is evaluated. Based on the assumption of the indivisibility and integrity of the metal’s grain, based on the postulates of the mesomechanical phenomenon of grain-boundary sliding, the idea is put forward that it is possible to conduct numerical experiments on the formation of cumulative jets with a different set step of the computational grid. A numerical calculation of the functioning of the cumulative charges of a conical and complex conical-annular shape of the lining for the side of the grain cell of 500, 250 and 125 μm is carried out. The efficiency of the jet formation process is visually assessed depending on the grain size according to the parameters distinguished: the directions of the velocity vectors of the material grain cells, and also the parameter γ is introduced - the angle between the reduced velocity vector of the head of the jet and the axis of symmetry of the jet formation. The results correlate with existing knowledge about the physics of the cumulation process: as the size of the side of the cell-grain decreases, the direction of the metal flow increases, the shape of the head of the jet “stretches”. The proposed method for numerical studies of the relationship between the microstructure of the cumulative lining and the breakdown ability of the cumulative charge opens up wide opportunities for further research, including when modeling cumulative facings with finer grains and for the various modifications of the mathematical formulation of the problem.