Titanium and its alloys are emerging materials with immense potential, widely used in aerospace, petroleum, chemical, pharmaceutical, and light industries. Over the past 30 years, China’s titanium industry has developed a complete system spanning raw materials, processing, manufacturing, R&D, and applications. The scale of titanium adoption reflects a nation’s technological advancement and military strength. Expanding titanium applications to drive large-scale production and prioritizing civilian uses while advancing military and high-tech sectors are critical strategies for China’s titanium industry in the 21st century.

Key Design and Manufacturing Characteristics of Titanium Equipment

1.High Chemical Reactivity

Titanium reacts with nitrogen and oxygen in air above 400°C, intensifying at 600°C. Reactions with hydrogen, oxygen, and carbon degrade its properties, increasing hardness and strength while reducing plasticity.

Design Considerations: Simplify structures to reduce weld stress concentration, ensure inert gas shielding for welds, and limit long-term use temperatures to ≤350°C (short-term ≤400°C).

2.Weldability and Compatibility

Commercially pure titanium and most titanium alloys are weldable. Corrosion-resistant alloys (e.g., Ti-Mo) can be used for localized reinforcement.

Limitations: Titanium cannot be fusion-welded to other metals due to brittle intermetallic compounds. Use methods like brazing, explosion welding, or threaded connections for hybrid joints.

3.Low Elastic Modulus and Thermal Expansion

Titanium’s elastic modulus is half that of carbon steel/stainless steel, requiring thicker sections for rigidity in bending-critical designs.

Thermal expansion coefficient is 2/3 of carbon steel and half of stainless steel. Account for thermal stress in titanium-lined equipment or mixed-material exchangers.

4.Temperature-Dependent Strength

Tensile strength decreases significantly at elevated temperatures (e.g., 50% reduction at 250°C). Use temperature-specific strength limits in design calculations.

5.Welding and Corrosion Avoidance

Joint Design: Minimize weld seams; avoid cross-joints. Use large titanium plates to reduce welds.

Corrosion Prevention: Eliminate gaps (e.g., replace bolts with welds) or use corrosion-resistant fillers. For unavoidable gaps (e.g., flange seals), select titanium alloys resistant to crevice corrosion.

6.High Yield-to-Tensile Ratio

Commercially pure titanium exhibits a yield strength close to its tensile strength. Yield-to-tensile ratios range from 0.75 (390 MPa) to 0.85 (680 MPa). Adjust safety factors accordingly.

7.Gallling Tendency

Untreated titanium surfaces are prone to galling in friction applications. Avoid using titanium for rotating components unless specially treated.

8.Machining Challenges

Threading titanium is difficult due to chip adhesion and tool breakage. Avoid blind holes or excessively long through-holes; relax tolerance grades in threaded designs.

Applications of Titanium Equipment

Aerospace: Lightweight structural components and engine parts.

Chemical/Petrochemical: Reactors, heat exchangers, and piping in corrosive environments (e.g., chlor-alkali plants, urea synthesis).

Pharmaceutical: Equipment resistant to acids and organic solvents.

Marine Engineering: Offshore platforms, desalination plants, and ship components.

Power Generation: Condenser tubes in coastal power stations.

Conclusion

Titanium’s unique properties drive its adoption across critical industries. Addressing design challenges (e.g., welding, thermal expansion) and leveraging its corrosion resistance ensure reliable performance in demanding applications.