SHAPE AND DIMENSIONS OF FRAGMENTED BANDS AFTER COLD DRAWING AND INTENSE PLASTIC DEFORMATION OF THE COPPER

Abstract

In this work, experimental methods were used to study the refinement of the structure of commercially pure copper (grade M 1) after double cold (at room temperature) plastic deformation by drawing and subsequent severe plastic deformation by equal channel angular pressing. The paper presents the results of measuring the structural components obtained on thin sections and foils cut from the cross-section of samples with a diameter of 20 mm after four and eight passes through the press channel with a 90° rotation after each pass (route Bc). A transmission electron microscope was used to study the structure. To compare changes in the microstructure at the mesolevel (less than we used the data obtained earlier in the study of copper samples using a scanning electron microscope. It is shown that after 4 passes and 8 passes, the deformation bands are formed – fragments (from in length), which alternate with transition bands – fragments with a dislocation structure. After 8 passes, the average size of the fragment was about 300 nm. As a result of crossing the shear bands in eight passes, diamond-shaped zones 1.5´1.5 mm was formed, in which fragmented deformation bands with less dislocation was surrounded by transition dislocation bands and fragments with dislocations. At the macro level, the copper structure obtained after 4 passes can have anisotropy of mechanical properties. The numerical characteristics of the structural components of copper after severe cold plastic deformation presented in the article make it possible to understand the structure refinement scheme at the mesoscale.