Characteristic Features in the Incremental Extrusion of Short Slugs of Composite Materials through Square Dies

Summary

An experimental investigation is made into forward extrusion of short length slugs of composite materials through square dies under both the plane strain and the axi-symmetric flow conditions at reductions of 25, 50 and 75 per cent in cross-sectional areas. Two types of composite specimens were made of copper and alumiminium, one type had either a strip of copper, a hard material, sandwiched between two aluminium strips as A1:Cu:A1,or a strip of aluminium, a soft material, sandwiched between two copper strips as Cu:A1:Cu, as plane strain flow, and in the other type, either a copper rod was inserted between an aluminium tube as A1:Cu, or a rod of aluminium was placed between a copper tube as Cu:A1 as in an axi-symmetric flow situation. The results of specific extrusion pressure, $$, are shown plotted against specific reduction in area, ℓ_n(1/_1−r) in each case and the results compared with a simple approximate analysis given. The mean equivalent yield stress, Y_e, of the composite was the total strength of the composite and calculated on the basis of relative volumetric proportion of each material in the composite. Some of the typical features of the process hitherto not reported are also presented and the results commented upon.