Aug 9 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
Machinability
Forming
Welding
Annealing
Forging
Hot Working
Cold Working
Applications
Introduction
Titanium mixed with other chemical elements such as aluminum, tin, molybdenum and zirconium produces a wide range of titanium alloys.
Grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy is an alpha-beta alloy. It is designed with high strength, intermediate creep strength, and fracture toughness. The following sections will discuss in detail about grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy.
Chemical Composition
The chemical composition of grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy is outlined in the following table.
|
Element |
Content (%) |
|
Titanium, Ti |
86 |
|
Aluminum, Al |
6 |
|
Chromium, Cr |
2 |
|
Tin, Sn |
2 |
|
Zirconium, Zr |
2 |
|
Molybdenum, Mo |
2 |
|
Iron, Fe |
≤ 0.25 |
|
Silicon, Si |
0.25 |
|
Oxygen, O |
≤ 0.14 |
|
Carbon, C |
≤ 0.040 |
|
Nitrogen, N |
≤ 0.030 |
Physical Properties
The physical properties of grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
4.65 g/cm3 |
0.168 lb/in3 |
|
Melting point |
≤ 1650 °C |
≤ 3000 °F |
Mechanical Properties
The following table shows mechanical properties of grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
1120 MPa |
162000 psi |
|
Yield strength |
1010 MPa |
146000 psi |
|
Poisson’s ratio |
0.33 |
0.33 |
|
Elastic modulus |
108 GPa |
15700 ksi |
|
Shear modulus |
46.0 GPa |
6670 ksi |
|
Elongation at break |
14% |
14% |
Thermal Properties
The thermal properties of grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@0.000-100°C/32-212°F) |
9.20 µm/m°C |
5.11 µin/in°F |
|
Thermal conductivity |
7.80 W/mK |
54.1 BTU in/hr.ft².°F |
Fabrication and Heat Treatment
Machinability
Grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy can be machined using slow speeds, right quantity of coolant flow and high feed rates. High-speed tools should be used for tooling this alloy and the recommended tool types are tungsten carbide designations C1-C4 or cobalt based.
Forming
Grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy can be hot or cold formed.
Welding
Weldabilty of grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy is rated as limited.
Annealing
For annealing grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy, the material has to be soaked at 704-815°C (1300-1500°F) for 2h, and then air cooled.
Forging
Rough forging can be performed at 899-954°C (1650-1750°F) and completed at 871-927°C (1600-1700°F).
Hot Working
Hot working enhances the overall ductility of the material.
Cold Working
Cold working features of this material is same as that of austenitic stainless steel. Post-work annealing is recommended to re-attain favorable performance properties.
Applications
Grade Ti 6Al 2Sn 2Zr 2Mo 2Cr 0.25Si alloy is chiefly used in airframe and jet engine components.