Titanium alloys are widely used in aerospace, biomedical, chemical engineering, and other fields due to their high specific strength, excellent corrosion resistance, and biocompatibility. However, their forming and processing face significant challenges, including high reactivity at elevated temperatures, substantial deformation resistance, and poor thermal conductivity, which lead to high manufacturing costs. This article provides a systematic overview of the main forming processes for titanium alloys and their respective application scenarios.

1. Casting

Casting is a process in which molten titanium alloy is poured into a mold cavity and, after cooling, yields a part.

• Principle and Features It is primarily carried out under vacuum or in the protection of an inert gas (such as argon) to prevent the titanium melt from reacting with air. This method is well-suited for producing parts with complex shapes and offers high material utilization.

• Limitation Castings are prone to defects such as shrinkage cavities and porosity, and their mechanical properties generally lag behind those of forgings.

• Typical Processes and Applications ： Vacuum Investment Casting (The lost-wax process) is the mainstream technique, often used to manufacture components such as aircraft engine casings, turbine blades, and medical implants like artificial joints.

2. Plastic Forming/Pressure Processing

This is the most commonly used titanium alloy forming method, typically carried out at high temperatures to reduce deformation resistance.

• Forging ：

  • Free forging Used for billet preparation of titanium ingots, producing semi-finished products such as disc billets and bar billets.

  • Forging Molding within the cavity of a die allows for the production of parts with intact flow lines and high mechanical performance, making it the primary manufacturing method for critical load-bearing components such as aircraft landing gear and engine disks. Isothermal forging (Mold and billet at the same temperature) is suitable for precision forgings with more complex shapes.

• Rolling It is used to produce profiles such as plates, strips, foils, bars, and tubes. Titanium plates serve as the foundation for manufacturing skins and heat exchangers.

• Compression and Tension Extrusion is used to produce pipes and profiled materials; drawing, on the other hand, is used to enhance the dimensional accuracy of wire and thin-walled tubes.

3. Powder Metallurgy

Parts are manufactured by compacting titanium alloy powder and then sintering it to achieve densification.

• Principle and Features It is a near-net-shape forming technology with a material utilization rate exceeding 95%. It can also produce composite materials that are difficult to achieve using conventional casting methods, resulting in a uniform microstructure.

• Limitation Metal powders are expensive, and the resulting products may contain residual pores.

• Typical Processes and Applications Including traditional pressing-sintering, Metal Injection Molding (Applicable to small, complex parts) and Hot isostatic pressing Additive manufacturing, in a broad sense, also falls under the category of powder metallurgy technology.

4. Additive Manufacturing (3D Printing)

Based on 3D model data, physical parts are manufactured by layer-by-layer accumulation of materials.

• Principle and Features This technology offers extremely high design freedom, enabling the fabrication of complex geometries—such as internal flow channels and lattice structures—that cannot be produced by conventional methods. It features high material utilization and eliminates the need for molds.

• Limitation The equipment and material costs are high, component dimensions are limited, surfaces usually require post-processing, and mechanical properties may exhibit anisotropy.

• Typical Technologies and Applications ： Laser Selective Melting (SLM) and Electron Beam Selective Melting (EBM) is a mainstream technology that directly manufactures parts with a density exceeding 99%. It has already been used for aerospace engine fuel nozzles and orthopedic implants with porous structures.

5. Special forming processes

• Superplastic forming By leveraging the property of titanium alloys, which exhibit extremely high elongation (exceeding 500%) under specific temperature conditions (around 900°C) and low-strain-rate deformation, the material can be shaped into complex curved components by using air pressure to conform it closely to the mold. The drawback is low production efficiency.

• Superplastic Forming/Diffusion Bonding Combined Process While performing superplastic forming, diffusion bonding of multilayer sheets can create integral, lightweight structures with cavities—this is an advanced technology in the aerospace field.

• Spinning It is suitable for manufacturing thin-walled rotating parts, such as nozzles and end caps, and offers the advantages of low tooling costs and excellent product performance.

Summary and Process Selection

The selection of a titanium alloy forming process depends on a comprehensive trade-off among part performance, shape complexity, production batch size, and cost.

In modern manufacturing, combined processes are often employed. For example, high-performance blanks are obtained through forging, and then local features are machined using a combination of mechanical machining and additive manufacturing to achieve comprehensive benefits.

References

1. Leyens, C., & Peters, M. (Eds.). (2003). Titanium and Titanium Alloys: Fundamentals and Applications Wiley-VCH.

2. Chinese Society of Mechanical Engineering. (2018). The Additive Manufacturing Technology Series. China Machine Press.

3. Boyer, R., et al. (2015). Materials Properties Handbook: Titanium Alloys (2nd ed.). ASM International.

4. Zhang Xiyuan, et al. (2009). Titanium Alloys and Their Applications. Chemical Industry Press.

5. Wang Huaming. (2015). Additive Manufacturing Technology for High-Performance Metal Components. Aerospace Manufacturing Technology .
   (Note: The above is a sample reference; in actual writing, please list the specific academic or industry sources accurately according to your citations.)

This answer was generated by AI and is for reference only. Please verify the information carefully.