Numerical and experimented study of UFG pure copper with high strength processed by Accumulative compound extrusion (ACE)

By the fast growing of electronic related industries, the demand for application of high strength with high conductivity materials is getting increased. In this paper, the accumulative compound extrusion is proposed as a severe plastic deformation method to produce UFG pure copper. An initial copper billet is placed in the die. In the first half- cycle the billet is pressed against the fixed mandrel by an upper punch which results in radial and forward flow of material. In the second half-cycle the billet is regained it's initial shape by pressing down punch. The accumulated plastic strain in each cycle of ACE processing is computed by analytical method and the obtained results showed significant amount of imposed plastic strain. The microstructure evolution during ACE processing was significant grain refinement of 110-240 nm from the initial grain size of 39µm at the end of second cycle. The microhardness examinations showed the increase of ACE processed Hardness to 98HV from the initial value of 57 HV. Also, the results of tensile tests showed the increase of yield and ultimate tensile strength by the factor of 2.07 and 1.13, respectively at the end of ACE second cycle. The flow behavior of material was simulated using FEM in DEFORM 2D software and the model predictions were in good agreement with the analytical results. The electrical conductivity examinations of the ACE processed samples showed the UFG pure copper with high strength and good conductivity in contrast with the alloyed copper parts.