Increasing strength and performance properties of bimetallic rods during severe plastic deformation

This study describes the evolution of the microstructure and mechanical properties of bimetallic aluminum-copper rods during straining by Equal channel angular pressing-drawing (ECAP-drawing). The study was conducted by means of a transmission electron microscope, EBSD analysis, tensile tests and determination of microhardness. The paper shows that an ultrafine-grained copper-aluminum composite with a gradient structure is formed during straining by ECAP-drawing. Microhardness of copper shell during 4 cycles of straining by ECAP-drawing increased from 57 to 165, and hardness of aluminum rod increased from 25 to 75 HV. This is associated with grain refinement and hardening of their boundaries by increasing the density of dislocations. Tensile test diagrams analysis has shown that straining leads to an increase in strength properties of bimetallic wire by 2 times, and as a result the plastic properties are also reduced by almost 2 times, but remain at a level applicable for further use. Application of such bimetallic rods in construction will allow reducing specific quantity of metal per structures without reduction of strength properties.