Abstract:
The TC4 titanium alloy powders prepared by hydrogenation-dehydrogenation (HDH) were used as the raw materials. The sintered TC4 titanium alloys were fabricated via cold isostatic pressing (CIP) followed by pressureless vacuum sintering. The TC4 sintered compacts were subjected to β single-phase region forging and subsequent solution-aging heat treatment. The effects of β forging and solution-aging heat treatment on the microstructure and mechanical properties of TC4 titanium alloys were investigated. The results show that the β forging drastically reduces the pore size inside the TC4 sintered compacts and remarkably increases the relative density of the alloys. The forged alloys exhibit the excellent room-temperature tensile properties with the ultimate tensile strength of 972 MPa and the elongation after fracture of 16.0%. After the solution and aging treatment, both the strength and the ductility of TC4 alloys change significantly. Compared with the forged alloys, the strength of heat-treated alloys increases by more than 200 MPa, while the elongation decreases from 16.0% to 8.2%. The strengthening effect induced by solution and aging treatment mainly originates from the precipitation of secondary α phases within the quenched matrix. The reduction in residual pore size greatly improves the fatigue properties of the sintered alloys. Under the maximum stress of 480 MPa and stress ratio of 0.1, the cycle fatigue life of β-forged TC4 alloys exceeds 7×10
6 cycles, and that of solution-aged TC4 alloys surpasses 10
7 cycles.