Microstructure and Mechanical Properties of Ti-6Al-6V-2Sn Alloy Bars Processed by High Temperature Thermomechanical Treatment

The forged bars of Ti-6Al-6V-2Sn dual phase titanium alloy were processed by high temperature thermomechanical treatment (HTTT). The treatment process including 880℃/1.5 h heating, fast cooling after 50% hot deformation and aging treatment at three temperatures. The microstructure, phase composition, tensile properties and fracture morphology of the alloys with different temperature aging treatment were analyzed by optical microscope (OM), scanning electron microscope (SEM), energy disperse spectroscopy (EDS) and electron universal testing machine. The results showed that the microstructure of the alloys after HTTT was primary α p phase, the secondary α s phase and residual β phase. With the increase of the aging temperature, the difference in Al content of α stability element was not that big and stable in α phase, but the content of β stability element in β phase increased gradually, especially the increase of V content was obvious. Meanwhile, the secondary α phase was gradually roughened, and the strengthening effect was gradually reduced. The tensile fracture of different temperature aging treatment was the typical cup fracture and the necking was obvious. After 50% hot deformation and aging at 580℃/4 h, the tensile strength, yield strength and elongation of the alloys reached 1209 MPa, 1143 MPa and 15.5% respectively, which achieved optimal match of plasticity and strength. © Editorial Office of Chinese Journal of Rare Metals. All right reserved.