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Why choose titanium alloy for 3D printing materials?

1. Excellent strength-to-weight ratio: The density of titanium alloy (about 4.5 g/cm³) is much lower than that of steel (about 7.8 g/cm³), but its strength is comparable or even higher. This is crucial for areas that need to reduce weight (such as aerospace).

2. Excellent corrosion resistance: Titanium has strong corrosion resistance in most natural environments and many chemical environments (including seawater and body fluids) without the need for additional coating.

3. Biocompatibility: Some titanium alloys (especially pure titanium and Ti-6Al-4V ELI) have excellent compatibility with human tissues, do not cause rejection or toxicity, and are ideal materials for orthopedic and dental implants.

4. Good high temperature performance: Titanium alloys can still maintain good strength and creep resistance at higher temperatures (300-600°C).

5. Non-magnetic: It is valuable in certain specific applications (such as medical devices, electronic devices).

Main 3D printing processes
The main metal 3D printing technologies used for titanium alloys all fall into two categories: powder bed fusion or directed energy deposition:
1. Powder bed fusion: This is the most widely used titanium alloy 3D printing technology.
o Selective laser melting: Use a high-power laser beam (usually a fiber laser or a disk laser) to selectively melt thin layers of metal powder. The powder works under the protection of an inert gas (argon, sometimes nitrogen).

o Electron beam melting: Use a high-energy electron beam to melt metal powder in a vacuum environment. The vacuum environment can effectively prevent titanium from oxidizing at high temperatures, and the electron beam has high energy density and fast scanning speed, which is particularly suitable for manufacturing large, dense, low residual stress titanium alloy parts. The EBM process usually requires preheating the powder bed to reduce residual stress, but may result in slightly higher surface roughness.

o Common features: The layer thickness is usually 20-100 microns, and extremely complex (such as topology optimization structure, lattice structure, internal flow channel) and high-precision parts can be manufactured. Post-processing usually requires the removal of support structures.

2. Directed Energy Deposition: This type of technology is usually used to manufacture or repair large parts and add features to existing parts.
o Laser Metal Deposition: Titanium metal powder (or wire) is fed into the molten pool through a nozzle and melted by the laser beam. The molten pool moves over the substrate or deposited material, and is built up layer by layer. It is usually carried out in an inert gas protection chamber.

o Electron Beam Additive Manufacturing: The principle is similar to LMD, but it uses an electron beam as a heat source and works in a vacuum environment.

o Common features: Fast deposition rate, large parts can be manufactured, functional gradient materials (composition changes) can be achieved, and it is particularly suitable for repair. The accuracy and surface finish are usually not as good as PBF.