Abstract
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To investigate the superplastic deformation behavior of cryorolled Ti-6Al-4V titanium alloy, tensile tests were carried out at 760 ��� and 830 ��� with different strain rate. The evolution of grain and microstructure has been studied using transmission electron microscopy and electron backscatter diffraction. When the tensile temperature was 760 ��� (< 0.5Tm, Tm��is absolute melting point of alloy.) and the strain rate was 5 �� 10���4��s���1, the fracture elongation of the sample reached 385%, showing good low-temperature superplasticity. Compared with the tensile temperature of 760 ���, the fracture elongation of the sample at 830 ��� was lower due to grain coarsening and oxidation. The strain rate sensitivity value m of all samples was larger than 0.3, which confirmed that the cryorolled Ti-6Al-4V titanium alloy with a non-equiaxed grains structure can achieve high superplasticity at a temperature lower than 0.5Tm, and indicated that the main deformation mechanisms in the tensile test at 760���830 ��� were grain rotation and grain boundary sliding. After the tensile test, the average grain size of all samples was less than 5����m, in which significant dynamic recrystallization and recovery occurred.