Ti-15V-3Cr-3Sn-3Al, commonly known as Ti-15-3, is a metastable beta titanium alloy developed to combine excellent cold formability in the solution-treated condition with high strength after ageing.
Its ability to be formed at relatively low strength and subsequently strengthened by heat treatment makes Ti-15-3 particularly useful for complex aerospace sheet and strip components.
The conventional alloy designation is Ti-15V-3Cr-3Sn-3Al, rather than Ti-15V-3Al-3Sn-3Cr.
Ti-15-3 Chemical Composition
| Element | Weight % |
|---|---|
| Titanium (Ti) | Remainder |
| Vanadium (V) | 14.0–16.0 |
| Chromium (Cr) | 2.5–3.5 |
| Tin (Sn) | 2.5–3.5 |
| Aluminium (Al) | 2.5–3.5 |
| Oxygen (O) | ≤ 0.13 |
| Nitrogen (N) | ≤ 0.05 |
| Carbon (C) | ≤ 0.05 |
| Hydrogen (H) | ≤ 0.015 |
| Iron (Fe) | ≤ 0.25 |
Applicable specifications may also control individual and total residual elements.
Physical Properties
Representative values include:
| Property | Value |
|---|---|
| Density | approximately 4.78 g/cm³ |
| Beta transus | approximately 750–770°C |
| Solution-treated tensile modulus | approximately 82 GPa |
| Aged tensile modulus | approximately 107–111 GPa |
Mechanical Properties and Heat Treatment
The strength of Ti-15-3 depends strongly on heat treatment, so a single tensile-strength figure should not be presented as a universal property.
Examples of specified minimum properties for solution-treated strip after ageing include:
| Ageing Treatment | UTS | 0.2% YS | Elongation |
|---|---|---|---|
| 538°C / 8 h | 1,000 MPa | 965 MPa | 7% |
| 496°C / 8 h | 1,172 MPa | 1,103 MPa | 5% |
| 482°C / 16 h | 1,241 MPa | 1,172 MPa | 5% |
This illustrates the alloy’s major advantage: strength can be tailored through ageing treatment.
Formability
Ti-15-3 has excellent cold formability in the solution-treated condition, substantially exceeding Ti-6Al-4V for many sheet-forming operations.
Components can therefore be formed before ageing to achieve their final strength.
Typical Applications
- Airframe structures
- Aerospace ducting
- Fire extinguishers
- Propellant tanks
- Fasteners
- Springs
Operating Temperature
Ti-15-3 is generally suitable for use at temperatures up to approximately 288°C (550°F). The allowable temperature for an actual component will depend on stress, duration, environment and design requirements.
Technical Note
Chemical and mechanical properties shown are representative of commonly referenced specifications. Requirements can vary by product form, thickness, heat treatment and governing standard. Material should be ordered to the required specification, and the supplied material test report (MTR) should be used to verify compliance.
