Determination of initial compression stresses when extruding bimetallic tubes with porous internal layer

This paper presents an analytical approach of the extrusion process applied to biomaterial tubes made of two prebonded metallic materials. The outer component of the bimetallic is a pore-free layer, whilst the internal one is a porous sintered tube. A generalized “slab method” of analysis, properly modified to describe the plastic behaviour of a porous-sintered material, developed in combination with the theory of thin shells, in order to investigate the initial stage of plastic deformation in the cylindrical chamber of the extrusion die. Numerical solution of the formulation suggested is conducted for components made of sintered and pore-free steel, respectively, and the effect of porosity on the stress–strain state of the bimetal is examined, allowing, in this manner, application of the method in relevant practical problems in the field of bimetallics