Some technological aspects of cold plug drawing of implosively welded duplex tubing

Abstract

The demand for composite, structurally strong, components has been growing steadily in the atomic energy, chemical, electrical and electronic, and aircraft industries. In addition to multimetallic sandwich plates, duplex tubular components have gained in importance, particularly where heat exchangers, pressure vessels, insulating systems and remote control rods are of importance. Bimetallic tubing is normally produced by co-extrusion or axial co-drawing and although these techniques are often satisfactory, they are likely to be inadequate in more sophisticated heat-exchange etc. systems where integral composites are required, or where more unusual combinations of, possibly, refractory metals are needed. The integrity of such systems or, indeed, their availability, can be assured however, if explosive welding is adopted. Although implosive welding of long tubes is feasible, the levels of energy required to produce them and the quality of the weld obtained may not be acceptable in industrial situations. Consequently, relatively short, large diameter, tubing is welded and is then conventionally processed. In the absence of any lubricant, grease, grit or other impurities on the weld interfaces, heat flow and, of course, mechanical properties, are substantially improved. This paper is concerned with an experimental assessment of the quality and mechanical properties of cold drawn, originally implosively welded, bimetallic tubing, and with the methods of testing.