A TEST DETERMINING THE ABILITY OF DIFFERENT MATERIALS TO UNDERGO SIMULTANEOUS PLASTIC-DEFORMATION TO PRODUCE METAL COMPOSITES

Special kinds of metal composites may be produced in the course of simultaneous plastic deformation, e.g. extrusion processes of various materials. However, in this case, metal flow is very complicated because of the non-homogeneity of the deformed material. It is usually assumed that during the plastic deformation of composite materials components must undergo an identical degree of deformation for a "sound" metal forming process. However, various structures and properties of simultaneously deformed materials make homogeneous flow quite impossible. It is very difficult to determine the appropriate working conditions of the process and the optimum parameters for the required metal composite. In this paper plastic deformation during a special test determining materials' ability to undergo simultaneous plastic flow and co-extrusion is analysed. The results of experimental work dealing with the manner of flow, changes in macro- and microstructure and character of deformational nonhomogeneity indicate that it is inadmissible to assume the same degree of deformation for components of a composite during the design of simultaneous metal forming processes. For a more exact determination of the character of material flow under real conditions it is proposed to apply a simple test for obtaining the required metal composite. This test is a special combination of upsetting and extrusion of simple composite specimens. Geometry variations, differentiation of material features and types (lead, lead alloy, aluminium, aluminium alloy, copper), and differentiation of the degree of deformation and structure are all included in the analysis.