ECA PRESSING UP TO FAILURE OF OXYGEN-FREE COPPER: STRUCTURE, PROPERTIES, EFFECT OF THE ROUTE

摘要

Structure and mechanical properties of oxygen-free copper depending on the route of ECA pressing at very high strain were studied. Deformation was performed at an angle of 90° between the channels. The maximum number of passes upon deformation by routes A, B_c, and C was N=25. The TEM and EBSD examinations revealed the appearance of subgrains and submicron grains. The average size of structure elements was ～200 nm (by TEM) and 230-460 nm (by EBSD). The fraction of high-angle boundaries at N=25 is between 69 and 77%. DSC analysis showed that the least equilibrium structure, including the structure of grain boundaries, is observed upon ECA pressing by route Bc All strength characteristics have the maximum values after route B_c. Elongation decreases at the early stage of ECA pressing, but then it is stabilized or grow. An increase in plasticity is most pronounced upon deformation by route B_c after sufficiently high strain.