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Titanium Alloys – Ti6Al2Sn4Zr6Mo (6-2-4-2) – Properties and Applications

Chemical Formula

Ti6Al2Sn4Zr6Mo

Background

Ti6Al2Sn4Zr6Mo  is a heat treatable alpha-beta alloy designed to combine the elevated temperature characteristics of Ti6Al2Sn4Zr2Mo with high strength levels. The alloy is thus competitive over Ti6Al2Sn4Zr2Mo up to approximately 454°C (850°F). It is used extensively in gas turbine applications such as discs and impellers. The alloy is also used for deep sour well piping and tooling and is listed in the MR0175 series of alloys suitable for this application.

Composition

Table 1. The composition of Ti6Al2Sn4Zr6Mo.

Content

C

<0.10%

Fe

<0.25%

N2

<0.5%

O2

<0.15%

Al

5.5-6.5%

Sn

1.8-2.2%

Zr

3.6-4.4%

Mo

1.8-2.2%

Si

0.06-0.1%

H2(bar)

<0.125%

H2(forging)

<0.150%

Ti

Balance

Designations

Other designations for Ti6Al2Sn4Zr6Mo include:

        AMS 4981

        MIL –T-9047

        UNS 56260

Key Properties

Physical Properties

Table 2. Typical physical properties for Ti6Al2Sn4Zr6Mo.

Property

Typical Value

Density g/cm3 (lb/ cu in)

4.65 (0.167)

Melting Range °C±15°C (°F)

1635 (2975)

Thermal Conductivity W/m.K (BTU/ft.h.°F)

6.9 (4.1)

Mean Co-Efficient of Thermal Expansion 20-100°C /°C (68-212°F /°F)

9.4x10-6 (5.2)

Mean Co-Efficient of Thermal Expansion 20-400°C /°C (68-752°F /°F)

10.3x10-6 (5.7)

Mean Co-Efficient of Thermal Expansion 20-600°C /°C (68-1112°F /°F)

10.4x10-6 (5.8)

Beta Transus °C±15°C (°F)

937 (1720)

Mechanical Properties

Table 3. Typical mechanical properties for Ti6Al2Sn4Zr6Mo.

Property

Minimum

Typical Value

Tensile Strength MPa (ksi)

1104 (160)

1310 (190)

0.2% Proof Stress MPa (ksi)

1035 (150)

1200 (174)

Elongation Over 2 Inches %

6

11

Reduction in Area %

12

Elastic Modulus GPa (Msi)

114 (17)

Hardness Rockwell C

42

Specified Bend Radius <0.070 in x Thickness (Annealed 857°C (1575°F), 5 min, FAC)

4.0

Table 4. Guaranteed minimum properties at 427°C (800°F).

Property

Value

Tensile Strength MPa (ksi)

931 (135)

0.2% Proof Stress MPa (ksi)

724 (105)

Elongation Over 2 Inches %

10

Reduction in Area %

30

Fabrication

        Weldability – Limited

        Forging – Rough 871-899°C (1600-1650°F), finish 843-899°C (1550-1650°F)

        Annealing – Duplex – 816-913°C, 1-2hr, AC or faster + 593°C 4-8hrs, AC.

        Solution Treating – 843-913°C (1550-1675°F), AC, OQ or WQ.

        Ageing – 579-607°C (1075-1125°F), 8hr, AC.

        Stress Relief Annealing – 482-649°C (900-1200°F), 1-4 hrs.

Applications

As mentioned previously, this alloy is most commonly used for gas turbine components such as impellers and discs as well as piping and tooling.

Source: Titanium Information Group.

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

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