Effect of high-dense electropulsing with different energies on the structure and strength of nickel cryorolled to different strains

The effect of thermomechanical treatment, based on combination of isothermal cryorolling at liquid nitrogen temperature to strains ranging from 30 to 90 % and subsequent single electric pulsing with an integral current density Kj up to 1.6 ×104 A2 s / mm4, on the structure and hardness of an initially coarse-grained pure nickel was studied. It is shown that the considered treatment is quite a powerful method to control the Ni structure and strength through grain and grain boundary design. The right chose of conditions of cryogenic straining and electro-heat action give ability to high efficient production of abnormally and partially work-hardened sheets with light tuning of crystallite size and fractions of recrystallized grains and high angle boundaries, in particular, the fine-grained sheet with a grain size of about 3 μm and 50 % fraction of the twin boundaries.