Jul 8 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Annealing
Forging
Hot Working
Cold Working
Aging
Applications
Introduction
Titanium mixed with other chemical elements such as aluminum, molybdenum and zirconium produces a wide range of titanium alloys.
Grade 6Al 2Sn 4Zr 6Mo titanium alloy possesses high strength at elevated temperatures, good hardenability and good weldability. It is heat-treatable alpha-beta alloy.
The following sections will discuss grade 6Al 2Sn 4Zr 6Mo titanium alloy in detail.
Chemical Composition
The chemical composition of grade 6Al 2Sn 4Zr 6Mo titanium alloy is outlined in the following table.
|
Element |
Content (%) |
|
Molybdenum, Mo |
6 |
|
Aluminum, Al |
6 |
|
Zirconium, Zr |
4 |
|
Tin, Sn |
2 |
|
Titanium, Ti |
Balance |
Physical Properties
The physical properties of grade 6Al 2Sn 4Zr 6Mo titanium alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
4.65 g/cm3 |
0.168 lb/in3 |
|
Melting point |
1595-1675°C |
2903-3047°F |
Mechanical Properties
The following table shows mechanical properties of grade 6Al 2Sn 4Zr 6Mo titanium alloy.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
1210 MPa |
175000 psi |
|
Yield strength |
1120 MPa |
162000 psi |
|
Poisson’s ratio |
0.33 |
0.33 |
|
Elastic modulus |
114 GPa |
16500 ksi |
|
Shear modulus |
42.9 GPa |
6220 ksi |
|
Elongation at break |
13 % |
13 % |
|
Hardness, Brinell |
360 |
360 |
|
Hardness, Knoop |
392 |
392 |
|
Hardness, Rockwell C |
39 |
39 |
|
Hardness, Vickers |
376 |
376 |
Thermal Properties
The thermal properties of grade 6Al 2Sn 4Zr 6Mo titanium alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@0.000-100°C/32-212°F) |
8.60 µm/m°C |
4.78 µin/in°F |
|
Thermal conductivity |
7.70 W/mK |
53.4 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to grade 6Al 2Sn 4Zr 6Mo titanium alloy are as follows:
-
AMS 4981
-
DIN 3.7164
-
MIL T-9046
-
PWA 1222
-
PWA 1223
-
PWA 1224
-
PWA 1225
Fabrication and Heat Treatment
Machinability
Grade 6Al 2Sn 4Zr 6Mo titanium 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 6Al 2Sn 4Zr 6Mo titanium alloy can be hot or cold formed.
Welding
Weldabilty of grade 6Al 2Sn 4Zr 6Mo titanium alloy is rated as limited.
Heat Treatment
The material can be solution treated at 843-913°C (1550-1675°F), and then air, oil or water quenched.
Annealing
For annealing grade 6Al 2Sn 4Zr 6Mo titanium alloy, the following process is used. Triplex-Beta minus 14°C (25°F), 1-2 h, air cool; 801-857°C (1490-1595°F), 1-4 h, air cool; 593°C (1100°F), 4-8 h, and air cool. To perform stress relief, heat the material to 482-649°C (900-1200°F), hold for 1-4 h and air cool.
Forging
In case of bar and billet, forge at 843-927°C (1565-1725°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.
Aging
Aging of grade 6Al 2Sn 4Zr 6Mo titanium alloy can be performed by holding the material at 579-607°C (1075-1125°F) for 8 h and then air cooling.
Applications
Grade 6Al 2Sn 4Zr 6Mo titanium alloy is used in the following application areas:
-
Intermediate-temperature jet engine components
-
Blades, discs, spacers and seals
-
In gas turbine discs and impellers
-
In deep sour well components.