The mechanics of wave formation in impact welding

If two metal plates are brought together at a sufficiently high relative velocity, a jet may form which removes much of the surface impurities, and a strong bond occurs. The purpose of this paper is to decribe the formation of a wave interface, and to suggest why a bond often occurs without the appearance of such waves. It is assumed that for sufficiently high values of the shear strain rate, above about 107 sec-1, the metals act as inviscid fluids; a model of a two-dimensional, incompressible, inviscid jet impinging on a plane boundary is considered, and the wave formation is thought to be due to a Helmholtz instability. Below this critical strain rate, the metals act as viscid fluids, and the viscosity acts to remove the instability.