Microstructure evolution and mechanical property of pure copper after multi-axial compression were investigated.Microstructure

evolution with the number of compressions was examined by scanning electron microscopy.The microhardness variation and distribution were investigated by measuring the Vickers microhardness on the middle section.The results show that dislocation division is the main mechanism of grain refinement.The subgrain misorientation increases by dislocation absorption and rearrangement with the increase of dislocation density and the rotation of compression axis,which leads to the grain refinement gradually.The ultra-fine grains are obtained in the most regions after 12 compressions.The microhardness is improved obviously, while its distribution on the middle plane is ununiform due to the friction between the billet and anvils, higher at the centeral portion and lower at the circumambience.