Quantitative Analysis Of The Effect Of Deformation Temperature On Microstructure Evolution And Mechanical Property Of Isothermally Forged Bt25y Titanium Alloy

In order to confirm the optimal isothermal forging process for BT25y titanium alloy, the effect of deformation temperature ranging from 880 degrees C to 1005 degrees C on the microstructures and mechanical properties was studied. Quantitative relationships between microstructure characteristics and mechanical properties were obtained. The deformation mechanisms were researched by the analysis of dislocation morphologies. Result shows that with elevated deformation temperature, the microstructure varies from equiaxed structure to bimodal structure, then basket-weave structure, and fmally Widmanstatten structure. Grain boundary a layer forms and secondary lamellar alpha coarsens gradually when deformed above 960 degrees C. As the forging temperature increases, the tensile strength shows a trend of first decrease and then rise, the elongation and reduction of area present an opposite tendency. Fracture mechanism changes from dominated ductile fracture to completely brittle cleavage fracture. The fracture toughness is well improved after beta-forging. The microstructure can achieve favorable thermal stability while deformed at the temperatures of 940 degrees C and 960 degrees C. (C) 2017 The Authors. Published by Elsevier Ltd. Peer-review under responsibility of the scientific committee of the International Conference on the Technology of Plasticity.