Simultaneous plastic deformation and joining of dissimilar sintered P/M preforms by cold extrusion

The present paper briefly describes the results obtained during investigation on a method to produce sound bimetallic tubes and transition joints between dissimilar metals by controlling the initial materials characteristics through powder metallurgy (P/M) and cold extrusion route. Simultaneous compression tests were carried out to obtain preliminary understanding on the simultaneous deformation of dissimilar sintered P/M preforms and also to generate plastic flow properties. These observations and data were used to optimize the process parameters for sound transition joining of dissimilar sintered P/M preform tubes and for co-extrusion of bimetallic tubes (steel-Cu and Cu-Al). Optimal post-joining heat treatment cycle was identified to enhance the weld strength of transition joints and bimetallic tubes. Significant information regarding the simultaneous deformation characteristics of dissimilar P/M preforms was inferred during compression and extrusion studies. Cold extrusion studies evinced the manufacturing flexibility and economy of current processing route.