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Challenges and difficulties of titanium materials in 3D printing

1. High cost:
o Titanium metal powder is expensive.
o Equipment purchase and maintenance costs are high.
o Process development, post-processing and verification costs are high.
o Inert/vacuum environment protection costs.

2. High process control requirements:
o Residual stress: Rapid melting and cooling lead to significant residual stress, which may cause deformation or even cracking. Scanning strategy, preheating (EBM) and support design need to be optimized.
o Porosity: Improper process parameters (laser power, scanning speed, layer thickness, overlap rate, etc.) will cause pores or unfused defects, affecting mechanical properties. Precise control is required.
o Contamination risk: Titanium is very easy to react with oxygen, nitrogen and hydrogen at high temperatures, resulting in embrittlement. Strict inert gas protection or vacuum environment is essential.

3. Microstructure and properties:
o Rapid solidification: Forms fine needle-shaped martensite α' phase (L-PBF) or lamellar α/β structure (EBM) that are different from traditional forgings. o Anisotropy: The mechanical properties (especially ductility) in the printing direction may be different from those in the perpendicular direction, which needs to be understood and controlled.
o Post-heat treatment: Hot isostatic pressing is usually required to eliminate internal micro-pores, and heat treatments such as annealing and solution aging are performed to adjust the microstructure and properties to reach or approach the level of forgings.
4. Surface quality: The surface of the printed part is usually rough ("step effect", powder adhesion), and post-treatment (sandblasting, machining, polishing, chemical polishing, electrolytic polishing) is required.
5. Support structure: Removing the support structure is time-consuming and labor-intensive, and may damage the surface of the part.
6. Certification and standardization: In strictly regulated fields such as aerospace and medical, establishing a reliable quality assurance system and obtaining certification is a long and complex process. Standards and specifications are still under development.