Hot Compression Deformation Behavior Of TC11 Titanium Alloy

The processing parameters of deformation and microstructure of the materials are important to the plastic forming. To improve the deformability of TC11 titanium alloy, the effect of different annealing techniques on the microstructure of TC11 titanium alloy were investigated. And the compression behaviors of original TC11 titanium alloy and annealed TC11 titanium alloy above the transformation point temperature were studied and the corresponding microstructures were analyzed. An index, which evaluates the deformability of TC11 titanium alloy, was brought forward. The compression parameters were as follows: compression temperature:800~1050℃; strain rate: 0.001~1s-1; compression reduction: 70%.The microstructure of original and annealed TC11 alloy was analyzed by SEM. The Widmanstaten structure of original TC11 alloy couldn't be changed by conventional annealing, dual annealing and annealing at above the transformation point temperature. Though there is little difference between fraction ofαphase in TC11 alloy after conventional annealing and that of the original TC11 alloy, the thickness ofαlamellar structure of TC11 alloy after conventional annealing is thicker than that of original TC11 alloy, and becomes thicker and thicker with increasing annealing temperature. The thickness and fraction ofαphase in TC11 alloy after dual annealing is improved greatly. Owing to the different forming time and growing time during cooling, the microstructure in TC11 alloy annealed at above the transformation point temperature is non-uniform. The microstructure heterogenity is consisted of coarseαphase and reticularβphase, the coarseαβlaminas, fineαβlaminas which is nearly 60%.It can be seen from stress-strain curves that dynamic recrystallization occurred during hot compression for both original TC11 alloy and TC11 alloy annealed at above the transformation point temperature. Meanwhile, the flow stress decreases with increasing temperature and decreasing strain rate. Moreover, the strain-softening phenomenon decreases with increasing temperature. And the maximum was obtained at strain rate of 0.1s-1. The flow stress of alloy after above the transformation point temperature is lager than that of original alloy due...