Strain-Induced Superplastic Deformation Process of TC4 Titanium Alloy Based on Maximum m Value Method

The superplastic deformation characteristics of TC4 titanium alloy were investigated within temperature of 850-950 ℃ and pre-strain of 1.2-2.0 by the method of strain-induced superplastic deformation based on the maximum m value method. Then the optimum process parameters were determined. The results show that the elongation of the alloy decreased with the increase of the deformation temperature under the same pre-stain. Dynamic recrystallization obviously occurred in the alloys after superplastic deformation, the higher of the deformation temperature, the coarser the grains were. The best process parameters of the strain-induced superplastic deformation were the deformation temperature of 850 ℃ and pre-strain of 1.5, and the elongation ratio could reach 2 147%.