Optimization on microstructure and mechanical properties of powder metallurgy TA15 titanium plates by annealing treatment

Hot rolling with powder metallurgy (PM) is one of the effective methods to prepare higher-alloying and lower cost titanium alloys plates. In this study, the PM-TA15 sintered billets were hot rolled at 1100 degrees C under 2 passes with 80 % rolling reduction within 60 % reduction rate in each pass without annealing among passes, and the asrolled plates were annealed at 900-1100 degrees C for 2-4 h. The effects of annealing temperature and time on the microstructure and properties of PM-TA15 plates and their evolution mechanisms were investigated. The results indicated that the anisotropy of the microstructure and properties, plasticity and toughness of the plates was significantly improved. The plates presented finer and more uniform basketweave or bimodal structure, and the grains were controlled within {0001}, {0110} and {1210} misorientation, and the maximum texture strength was reduced to less than 1.5. After annealing at 900-1000 degrees C for 4 h, the tensile strength, yield strength and elongation of the plates were 1041-1051 MPa, 953-963 MPa and 15.5-17.5 %, respectively, and the strength difference between different orientations was only 10-15 MPa. The deformation and optimization of the plates depended on the synergistic effects of different slip systems, and texture weakening and microstructure optimization were the key to improving the performance of the PM-TA15 plates.