Microcrack healing and local recrystallization in pre-deformed sheet by high density electropulsing

The microcracks in the titanium alloy sheet are produced by plastic deformation. The damaged sheet is treated by high density electropulsing (maximum current density J(max) = (4.75-5.32) x 10(3) A/mm(2), period t(p) =110 mu s) under ambient conditions. The optical microscope (OM) and scanning electron microscope (SEM) are used to examine the changes of the microstructure before and after the electropulsing treatment. The plasticity recovery degree of the titanium alloy sheet is studied using uniaxial tensile tests. Experimental results indicate that the plasticity of the specimens with 8% of pre-plastic deformation is nearly recovered completely by electropulsing treatment under certain conditions. Microcracks resulted from plastic deformation are healed, the local recrystallization occurs in the sheet metal after the electropulsing treatment. The research results show that the electropulsing treatment is an effective method to increase the forming limit of titanium alloy sheet. (c) 2007 Elsevier B.V. All rights reserved.