Titanium Alloys – Ti6Al5Zr0.5Mo0.25Si Physical and Mechanical Properties, Fabrication and Applications

 

Chemical Formula

Ti6Al5Zr0.5Mo0.25Si

Background

Also known as Timetal 685, this is a well established alloy for high temperature use, and possesses good creep resistance up to 520°C (970°F). It was developed for aerospace applications. It is a near alpha alloy and combines good creep strength, weldability and ease of working. Forging temperatures above the beta transus can be used. It is widely used in gas turbine engines.

Composition

Table 1. The composition of Ti6Al5Zr0.5Mo0.25Si.

Content

Al

5.7-6.3%

Zr

4.5-6.0%

Mo

0.25-0.75%

Si

0.15-0.35%

Fe

<0.05%

C

<0.08%

O2

<0.20%

N2

<0.03%

H2

<100ppm

Others

<0.40%

Ti

Balance

Key Properties

Physical Properties

Table 2. Typical physical properties for Ti6Al5Zr0.5Mo0.25Si.

Property

Typical Value

Density g/cm3 (lb/ cu in)

4.45 (0.16)

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

9.3x10-6 (5.2)

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

9.8x10-6 (5.4)

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

10.1x10-6 (5.6)

Beta Transus °C±15°C (°F)

1020 (1868)

Mechanical Properties

Table 3. Typical mechanical properties for Ti6Al5Zr0.5Mo0.25Si rod.

Property

Typical

0.2% Proof Stress MPa (ksi)

914 (133)

Tensile Strength MPa (ksi) sheet

1020 (148)

Elongation on 5D %

11

Reduction in Area %

22

Notched Tensile Ratio (Kt3)

1:1.6

Table 4. Typical mechanical properties for Ti6Al5Zr0.5Mo0.25Si billet.

Property

Typical

0.2% Proof Stress MPa (ksi)

900 (130)

Tensile Strength MPa (ksi) sheet

1030 (149)

Elongation on 5D %

10

Reduction in Area %

20

Notched Tensile Ratio (Kt3)

1:1.6

Reduction in Area %

39.6

Hardness Hv

380

Fabrication

        Weldability – Good

        Forging – Beta 1030 - 1050°C (1886-1922°F), Alpha-beta 990-1010°C (1814-1850°F)

        Solution Treating - 1050°C (1922°F), 30 min OQ

        Ageing - 550°C (1022°F), 24 hr AC

Applications

As mentioned above Ti6Al5Zr0.5Mo0.25Si was designed for use in aerospace applications and has also been used in gas turbine engines.

Source: The Titanium Information Group

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

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