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Titanium Alloys - Ti4Al4Mo2Sn Properties and Applications

Chemical Formula

Ti4Al4Mo2Sn

Background

Also called Ti-4-4-2, this high strength forging alloy is used primarily for engine compressor blades and discs, as well as various airframe forgings. The high silicon content extends its useful strength and creep resistance into the intermediate temperature ranges up to 400°C (750°F).

Composition

Table 1. The composition of Ti4Al4Mo2Sn.

Content

Al

3.0-5.0%

Sn

1.5-2.5%

Mo

3.0-5.0%

Si

0.3-0.7%

O2

0.16-0.2%

Fe

<0.2%

C

<0.05%

N2

<0.03%

H2

<0.015%

Ti

Balance

Designations

Other designations for Ti4Al4Mo2Sn include:

        BSTA 45 to 51

        BSTA 57

Key Properties

Physical Properties

Table 2. Typical physical properties for Ti4Al4Mo2Sn.

Property

Typical Value

Density g/cm3 (lb/ cu in)

4.60 (0.166)

Volume Electrical Resistivity µohm.cm (µohm.in)

160 (63)

Thermal Conductivity W/m.K (BTU.in/ft2.hr)

7.6 (53)

Mean Thermal Expansion Co-eff 20-100°C /°C (/°F)

8.8 (4.9)

Mean Thermal Expansion Co-eff 20-200°C /°C (/°F)

9.0 (5.0)

Mean Thermal Expansion Co-eff 20-300°C /°C (/°F)

9.2 (5.1)

Mean Thermal Expansion Co-eff 20-400°C /°C (/°F)

9.3 (5.2)

Mean Thermal Expansion Co-eff 20-500°C /°C (/°F)

9.7 (5.4)

Mean Thermal Expansion Co-eff 20-600°C /°C (/°F)

10.1 (5.6)

Beta Transus °C±15°C (°F)

975 (1787)

Mechanical Properties

Table 3. Typical mechanical properties for Ti4Al4Mo2Sn.

Property

Minimum

Typical

Tensile Strength MPa (ksi) sheet

1104 (160)

1138 (165)

0.2% Proof Stress MPa (ksi)

959 (139)

1035 (150)

Elongation over 2 inches %

9

12

Reduction in Area %

38

Elastic Modulus GPa (Msi)

114 (17)

Fabrication

        Annealing – 900°C (1650°F), 30 min AC

        Solution Treating - 900°C (1650°F), 30 min AC or fast AC

        Ageing - 500°C (900°F), 24 hr AC

        Stress Relief Annealing - 650°C (1200°F), 2hr AC

Applications

As mentioned above, Ti4Al4Mo2Sn is suited to engine compressor blades and discs, as well as various airframe forgings.

Source: The Titanium Information Group

For more information on this source please visit The Titanium Information Group

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