Owing to excellent high-temperature mechanical properties, i.e., high heat resistance, high strength, and high corrosion resistance, Ti alloys can be widely used as structural components, such as blades and wafers, in aero-engines. Due to the complex shapes, however, it is difficult to fabricate these components via traditional casting or plastic forming. It has been proved that additive manufacturing (AM) is an effective method of manufacturing such complex components. In this study, four main additive manufacturing processes for Ti alloy components were reviewed, including laser powder bed melting (SLM), electron beam powder bed melting (EBM), wire arc additive manufacturing (WAAM), and cold spraying additive manufacturing (CSAM). Meanwhile, the technological process and mechanical properties at high temperature were summarized. It is proposed that the additive manufacturing of titanium alloys follows a progressive path comprising four key developmental stages and research directions: investigating printing mechanisms, optimizing process parameters, in situ addition of trace elements, and layered material design. It is crucial to consider the development stage of each specific additive manufacturing process in order to select appropriate research directions. Moreover, the corresponding post-treatment was also analyzed to tailor the microstructure and high-temperature mechanical properties of AMed Ti alloys. Thereafter, to improve the mechanical properties of the product, it is necessary to match the post-treatment method with an appropriate additive manufacturing process. The additive manufacturing and the following post-treatment are expected to gradually meet the high-temperature mechanical requirements of all kinds of high-temperature structural components of Ti alloys.

In this work, laser powder bed fusion (LPBF) was explored to fabricate TA15 (Ti-6Al-2Zr-1Mo-1V) titanium alloy based on the experimental design obtained by using the Taguchi method. The impact of processing parameters (including laser power, scanning speed, and scanning interval) on the density and microhardness of the as-LPBFed TA15 titanium alloy was analyzed using the Taguchi method and analysis of variance (ANOVA). The interaction among parameters on the density of the as-LPBFed TA15 titanium alloy was indicated by a response surface graph (RSR). When the laser energy density was adjusted to 100 J/mm³, the highest relative density could reach 99.7%. The further increase in the energy input led to the reduction in relative density, due to the formation of tiny holes caused by the vaporization of material at a high absorption of heat. Furthermore, in order to better reveal the correlation between relative density and processing parameters, the regression analysis was carried out for relative density. The results showed that the experimental and predicted values obtained by the regression equation were nearly the same.

In this study, TA15 titanium alloys were successfully prepared using selective laser melting (SLM). The results show that the microstructure of each TA15 specimen is composed of a large number of acicular α’ martensite crystals accompanied by a lot of dislocations and twin structures in the martensite due to non-equilibrium heating and cooling via SLM. After solution treatment and aging treatment, the martensite structure is successfully transformed into a typical duplex structure and an equiaxial structure. When there is an increase in the solution temperature, the size of the equiaxed primary α phase and the elongation of the specimen gradually increases, while the thickness of the layered secondary α phase and the tensile strength of the specimen decreases accordingly. After solution treatment at 1000 °C, the specimens show the best comprehensive mechanical properties, i.e., a high-temperature tensile strength of 715 MPa and a corresponding elongation of 24.5%. Subsequently, an appropriate solution–aging treatment is proposed to improve the high-temperature mechanical properties of SLMed TA15 titanium alloys in aerospace.