Jul 25 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Forging
Hot Working
Cold Working
Annealing
Other Designations
Applications
Introduction
Nicrofer 7016 TiAl alloy is a precipitation hardenable nickel-chromium-iron alloy that exhibits good corrosion resistance at high and low temperatures. The alloy also has excellent mechanical properties in cryogenic environments. The alloy is very similar to nicrofer 7016 TiNb alloy, except that its slightly modified composition imparts improved stress-rupture properties at 870°C (1600°F).
The following section will provide an overview of nicrofer 7016 TiAl alloy.
Chemical Composition
The chemical composition of nicrofer 7016 TiAl alloy is outlined in the following table.
|
Element |
Content (%) |
|
Chromium, Cr |
14 - 17 |
|
Iron, Fe |
5-9 |
|
Titanium, Ti |
2-2.6 |
|
Manganese, Mn |
1 |
|
Aluminum, Al |
0.9-1.5 |
|
Niobium+Tantalum, Nb+Ta |
0.7-1.2 |
|
Silicon, Si |
0.5 |
|
Carbon, C |
0.1 |
|
Sulfur, S |
0.01 |
|
Nickel |
Balance |
Physical Properties
The following table shows the physical properties of nicrofer 7016 TiAl alloy.
|
Properties |
Metric |
Imperial |
|
Density |
8.2 g/cm3 |
0.296 lb/in3 |
|
Melting point |
1390-1430°C |
2540-2600°F |
Mechanical Properties
The mechanical properties of nicrofer 7016 TiAl alloy are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile strength (Solution treated) |
782 MPa |
113 ksi |
|
Yield strength (Solution treated) |
391 MPa |
57 ksi |
|
Elongation at break (Solution treated) |
42% |
42% |
Thermal Properties
The thermal properties of nicrofer 7016 TiAl alloy are given in the following table.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@100°C/212°F) |
13.2 µm/m°C |
7.3 µin/in°F |
|
Thermal conductivity (@20°C/68°F) |
10.5 W/mK |
73 BTU.in/hrft².°F |
Fabrication and Heat Treatment
Machinability
Conventional machining techniques that are used for machining iron-based alloys can be used.
Forming
Nicrofer 7016 TiAl alloy has excellent ductility, and can be readily formed by all conventional techniques.
Welding
The alloy can be welded using commonly used welding techniques such as gas-tungsten arc welding, shielded metal-arc welding, gas metal-arc welding and submerged-arc welding.
Heat Treatment
Nicrofer 7016 TiAl alloy is heat treated at 1177°C (2150°F) for atleast 1 h and air cooled.
Forging
The alloy can be forged at the temperatures ranging from 1038 to 1204°C (1900 to 2200°F).
Hot Working
Hot working of nicrofer 7016 TiAl alloy can be accomplished in the temperature range of 982 to 1204°C (1800 to 2200°F).
Cold Working
Cold working may be performed using standard tooling.
Annealing
The alloy is annealed at 1177°C (2150°F) followed by air cooling.
Other Designations
An equivalent designation to nicrofer 7016 TiAl alloy includes DIN 2.4694.
Applications
Nicrofer 7016 TiAl alloy finds application in exhaust valves on heavy duty diesel engines.