Titanium Alloys – Ti5Al2.5Sn Grade 6

Chemical Formula

Ti5Al2.5Sn

Topics Covered

Mechanical Properties

Fabrication

Applications

Background

This alloy is most commonly used for airframe and jet engine applications requiring good weldability, stability and strength at elevated temperatures.

Ti5Al2.5Sn ELI

Ti5Al2.5Sn ELI has had extended use for liquid gas and propellant containment for rockets and space vehicles.

Composition

Table 1. The composition of Ti5Al2.5Sn Grade 6.

	Content
C	<0.08%
Fe	<0.5%
N₂	<0.05%
O₂	<0.2%
Al	4.0-6.0%
Sn	2.0-3.0%
H₂	<0.02%
Ti	Balance

Designations

Other designations for Ti5Al2.5Sn include:

· AMS 4910

· AMS 4926

· AMS 4966

· ASTM B265 Gr6

· ASTM B348 Gr6

· ASTM B381 Gr6

· MIL –T-9046 2A or ELI 2B

· MIL –T-9047 2A or ELI 2B

Key Properties

Physical Properties

Table 2. Typical physical properties for Ti5Al2.5Sn Grade 6.

Property	Typical Value
Density g/cm³ (lb/ cu in)	4.48 (0.161)
Melting Range °C±15°C (°F)	1571 (3860)
Specific Heat J/kg.°C (BTU/lb/°F)	540 (0.129)
Volume Electrical Resistivity ohm.cm (ohm.in)	157 (62)
Thermal Conductivity W/m.K (BTU/ft.h.°F)	7.7 (53)
Mean Co-Efficient of Thermal Expansion 0-100°C /°C (0-212°F /°F)	9.5x10^-6 (5.3)
Beta Transus °C±15°C (°F)	1038 (1900)

Mechanical Properties

Table 3. Typical mechanical properties for Ti5Al2.5Sn Grade 6.

Property	Minimum	Typical Value
Tensile Strength MPa (ksi)	828 (120)	972 (141)
0.2% Proof Stress MPa (ksi)	779 (113)	897 (130)
Elongation Over 2 Inches %	10	16
Reduction in Area %	25
Elastic Modulus GPa (Msi)		110 (16)
Hardness Rockwell C		36
Specified Bend Radius <0.070 in x Thickness		4.0
Specified Bend Radius >0.070 in x Thickness		4.5
Post-weld stress relieved Welded Bend Radius x Thickness	5.0
Charpy, V-Notch Impact J (ft.lbf)		26 (19)

Fabrication

· Weldability – Excellent

· Forging – Rough 1010-1030°C (1850-1900°F), finish 954-1010°C (1750-1850°F)

· Annealing – 718-843°C (1325-1550°F), 10 min-4hr, AC

· Stress Relief Annealing – 538-650°C (1000-1200°F), 15-60 mins, A.C.

Applications

As mentioned previously, this alloy is most commonly used for airframes and jet engines applications requiring good weldability, stability and strength at elevated temperatures.

The ELI grade has been used for liquid gas and propellant containment for rockets and space vehicles.