Titanium Grade 6 (Ti-5Al-2.5Sn) is a near-alpha titanium alloy engineered for excellent strength retention at elevated temperatures, superior creep resistance, and long-term structural stability. It is widely used in aerospace and high-temperature industrial applications where thermal reliability is more critical than peak room-temperature strength.
Material Classification
| UNS | R55250 |
|---|---|
| ASTM | B265, B348 |
| AMS | 4918, 4919 |
| Alloy Type | Near-Alpha Titanium Alloy |
| Strength Level | Medium-High |
| Key Feature | Elevated-Temperature Performance |
Metallurgical Behavior & Strengthening
Titanium Grade 6 is not heat-treatable for significant strengthening. Strength is achieved through solid-solution strengthening from aluminum and tin, combined with controlled grain size.
✔ Predominantly alpha-phase microstructure
✔ Excellent resistance to creep and thermal fatigue
✔ Superior oxidation resistance compared to alpha-beta alloys
✔ Long-term microstructural stability
High-Temperature & Oxidation Performance
Grade 6 is optimized for continuous elevated-temperature service:
✔ Retains strength at 350–450 °C
✔ Better creep resistance than Ti-6Al-4V (Grade 5)
✔ Good oxidation resistance in air
✔ Stable under prolonged thermal exposure
Fabrication & Processing
Weldability: Excellent, with no complex post-weld heat treatment
Formability: Good (hot forming preferred)
Machinability: Moderate, easier than Ti-6Al-4V
Applications
✈️ Aerospace: engine casings, compressor components, hot-section airframe parts
🚀 Defense & Space: missile components, thermal structures
🏭 Industrial & Power: high-temperature pressure vessels, heat shields
⚙️ Automotive & Performance: exhaust systems, racing applications
Advantages
✔ Excellent elevated-temperature strength
✔ Superior creep resistance
✔ Good weldability
✔ Thermal stability over long service life
✔ Lightweight with high performance
Limitations
⚠ Lower room-temperature strength than Grade 5
⚠ Not suitable for extreme mechanical loads
⚠ Limited availability compared to Ti-6Al-4V
High-Temperature Titanium Comparison
| Grade | Temperature Capability | Strength | Typical Use |
|---|---|---|---|
| Grade 5 | ~300 °C | High | Structural aerospace |
| Grade 6 | ~450 °C | Medium-High | Hot-section parts |
| Grade 9 | ~300 °C | Medium | Tubing |
| Ti-8Al-1Mo-1V | ~500 °C | Medium-High | Supersonic aircraft |
Summary:
Titanium Grade 6 (Ti-5Al-2.5Sn) is a proven near-alpha titanium alloy optimized for
elevated-temperature service. Its excellent creep resistance, oxidation resistance,
weldability, and thermal stability make it ideal for aerospace, defense, and industrial
applications where continuous heat exposure is a primary concern.