Jun 20 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Annealing
Heat Treatment
Forging
Hot Working
Cold Working
Aging
Applications
Introduction
Titanium alloys are known to be light weight alloys with excellent corrosion resistance, very high tensile strength and toughness.
Grade 5 Ti-6Al-4V alloy is the most widely used of all the titanium grades. It is a medium to high strength general-purpose alloy. It is also referred to as an alpha-beta alloy. This alloy is fully heat treatable in sections measuring up to 15mm. It can be heated up to 400°C (750°F), and has good tensile properties at room temperature, creep resistance up to 325°C and very good fatigue strength. It is also known to be highly resistant to general corrosion in sea water.
The following sections will discuss in detail about grade 5 Ti-6Al-4V alloy.
Chemical Composition
The chemical composition of grade 5 Ti-6Al-4V alloy is outlined in the following table.
|
Element |
Content (%) |
|
Titanium, Ti |
87.6 - 91 |
|
Aluminum, Al |
5.5 - 6.75 |
|
Vanadium, V |
3.5 - 4.5 |
|
Iron, Fe |
≤ 0.40 |
|
Oxygen, O |
≤ 0.20 |
|
Carbon, C |
≤ 0.080 |
|
Nitrogen, N |
≤ 0.050 |
|
Hydrogen, H |
≤ 0.015 |
Physical Properties
The physical properties of grade 5 Ti-6Al-4V alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
4.43 g/cm3 |
0.160 lb/in3 |
|
Melting point |
1674 °C |
3045 °F |
Mechanical Properties
The following table shows mechanical properties of grade 5 Ti-6Al-4V alloy.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
≥ 895 MPa |
≥ 130000 psi |
|
Yield strength |
≥ 828 MPa |
≥ 120000 psi |
|
Poisson’s ratio |
0.31 |
0.31 |
|
Elastic modulus |
105-120 GPa |
15200-17400 ksi |
|
Shear modulus |
41-45 GPa |
5950-6530 ksi |
|
Elongation at break |
≥ 10 % |
≥ 10 % |
Thermal Properties
The thermal properties of grade 5 Ti-6Al-4V alloy are tabulated below.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@0.000-100°C/32-212°F) |
9 µm/m°C |
5 µin/in°F |
|
Thermal conductivity |
6.60W/mK |
45.8 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to grade 5 Ti-6Al-4V alloy are as follows:
|
AMS 4928 |
AMS 4965 |
AMS 4967 |
MIL T-81915 |
MIL T-9046 |
|
AMS 4920 |
AMS 4954 |
ASTM B265 |
MIL T-81556 |
MIL T-9047 |
|
AMS 4911 |
AMS 4935 |
ASTM B348 |
MIL F-83142 |
SPS M618 |
|
AMS 4906 |
AMS 4934 |
ASTM B381 |
GE C50TF12 |
DMS 1570 |
|
AMS 4905 |
AMS 4930 |
DIN 3.7164 |
|
|
Fabrication and Heat Treatment
Machinability
Although tough, grade 5 Ti-6Al-4V alloy can be machined using the right quantity of coolant flow, slow speeds 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 5 Ti-6Al-4V alloy can be hot or cold formed. The forming techniques include hydropress, stretch or drop-hammer.
Welding
Weldability of grade 5 Ti-6Al-4V alloy is rated as fair.
Annealing
Annealing can be performed by holding at 732°C (1350°F) between 1/4 and 4 h, then furnace cooled to 566°C (1050°F) followed by air cooling. In case of forgings and bars, furnace cooling is not required.
Heat Treatment
Solution treatment of the material is done at 904-954°C (1660-1750° F) for 2 h, which is followed by water quench process.
Forging
Rough forging of grade 5 Ti-6Al-4V alloy should be performed at 982°C(1800°F), and finished at 968°C (1750°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 a moderately tempered austenitic stainless steel. Post-work annealing is recommended to re- attain favorable performance properties.
Aging
Aging of grade 5 Ti-6Al-4V alloy can be performed at 538°C (1000°F) for 4 h, and then air cooled.
Applications
Grade 5 Ti-6Al-4V alloy is a popular titanium alloy and is widely used in several industries including aerospace, power generation, marine, and offshore industries.