To investigate the effect of the electropulsing on dislocation mobility,specimens cut from the cold-rolled titanium sheet were treated by high density electropulsing with the maximum current density of 7.22,7.64,7.96 kA/mm 2 ,pulse period 110μs.The internal friction and elastic modulus were measured by a dynamic mechanical analyzer（DMA）.When strain amplitude lowers a certain critical one,the damping of the electropulsed titanium sheet is lower than that of the cold-rolled one.When the strain amplitude exceeds the critical one,the damping of the electropulsed titanium sheet is extraordinarily higher than that of the cold-rolled or conventional annealed one.Furthermore,it is found that the damping peak of the electropulsed titanium sheet shifts to lower temperature compared with the conventional annealed one.It is demonstrated that the electropulsing treatment can decrease dislocation tangles and enhance dislocation mobility.
Specimens cut from the cold-rolled commercially pure （CP） Ti sheet were treated by high density electropulsing （the maximum current density 7.22 kA/mm2, pulse period 110 las）. The deformation behaviors of the CP Ti specimens at different states were determined by the uniaxial tensile test. The microstructure morphologies were observed by the optical microscopy. The results show that the electropulsing induced formation of f＇me equal-axial grains and lamellar microstructures, which leads to the strength of the electropulsed CP Ti higher than that of the conventional annealed CP Ti. After electropulsing, the tensile strength and yield strength are increased by 100 MPa. And the electropulsed CP Ti has a good plasticity. The experimental results demonstrate that the electropulsing provides an effective approach to enhance the strength of cold-rolled CP Ti sheet and retain the required high ductility.
In order to optimize the ductility of orthorhombic Ti2AlNb-based alloys sheet,Ti22Al27Nb sheet was treated by high density electropulsing（J max =6.80 7.09 kA/mm2,tp =110 μs） under ambient condition.Microstructures were observed by SEM,and the tensile properties were also studied using uniaxial tension tests.The experimental results show that electropulsing can refine the microstructures of Ti22Al27Nb sheets.The specimen with the fine and homogeneous microstructures has good plasticity,and its elongation reaches 19.4%.The mechanism about the effect of electropulsing treatment on the microstructure of Ti22Al27Nb sheets was discussed.It was thought that the increase in nucleation rate during phase transformation and a very short treating time were regarded as the main reasons of producing smaller grains and increase in the plasticity by electropulsing.
