Co-extrusion of dissimilar sintered P/M preforms - An explored route to produce bimetallic tubes

The present article reports the results of preliminary studies, carried out for the first time, related to the production of bimetallic tubes by tailoring the initial materials characteristics through powder metallurgy (P/M) and cold extrusion route. It is shown that the domination of consolidation (volume change) during simultaneous deformation of P/M preforms reduces the differential velocity between the core and the sleeve as indicated by lower failure propensity of extrudes. High interfacial friction at the dissimilar P/M preform interface and in turn the high interfacial bond aids the sound flow over a wide range of processing conditions. In addition, the non-uniformities of deformation would be accommodated by the softer preform near the interface through micro-mechanical interactions. It is believed that the current approach of producing the bimetals greatly enhances the manufacturing flexibility and reduces the tool cost. (c) 2005 Elsevier B.V. All rights reserved.