Effect of aging temperature on microstructure, texture and tensile properties of Ti662 titanium alloy

In order to study the effect of aging temperature on the microstructure, texture and tensile properties of Ti662 titanium alloy, the hot-rolled Ti662 titanium alloy sheet was solution treated at 920 °C (2 h, water cooling) and aged at different temperatures (500 °C, 530 °C, 560 °C) (6 h, air cooling). The microstructure, phase composition, texture characteristics and mechanical properties of the alloy were systematically analyzed by means of optical microscope, scanning electron microscope, electron backscatter diffraction, X-ray diffraction, transmission electron microscope and room temperature tensile test. The results show that the microstructure of the alloy after solution treatment is composed of primary α phase, acicular α′ martensite and orthorhombic α martensite. The texture is R type and the texture strength is 3.04. After aging treatment, the metastable martensite phase is decomposed into secondary α phase and a small amount of residual β phase (as indicated by XRD and TEM analyses), and the texture type remains unchanged, but the texture strength increases from 4.58 to 6.63 with the increase of aging temperature. In terms of mechanical properties, aging treatment significantly improves the tensile strength and yield strength of the alloy but reduces the elongation after fracture. With the increase of aging temperature from 500 °C to 560 °C, the tensile strength increases from 1,431 ± 14.14 MPa to 1,472 ± 14.09 MPa, the yield strength increases from 1,172 ± 13.11 MPa to 1,211 ± 13.18 MPa, and the elongation decreases from 8% ± 1.41%–5% ± 1.40%. These results demonstrate a clear trade-off between strength and ductility with varying aging temperature. For engineering applications, aging at 530 °C is recommended as a preferred condition for components requiring a combination of strength and sufficient formability or fracture safety, whereas aging at 560 °C is more suitable for load-bearing components where maximizing strength is the primary design objective.