Nov 26 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesThermal PropertiesFabrication and Heat Treatment Machinability Forming Welding Heat Treatment Forging Hot Working Cold Working Annealing AgingApplications
Introduction
Super alloys have good creep and oxidation resistance. They consist of a number of elements in different combinations to achieve the desired result. They are also known as high performance alloys, and are available in different shapes. They can be strengthened by work hardening, precipitation hardening, and solid-solution hardening.
Incoloy 907™ is a nickel-cobalt-iron alloy. It has high strength and low thermal expansion coefficient at temperatures up to 800°F. The datasheet given below will discuss about Incoloy 907™.
Chemical Composition
The following table shows the chemical composition of Incoloy 907™.
| Elements |
Content (%) |
| Iron, Fe |
42 |
| Nickel, Ni |
38 |
| Cobalt, Co |
13 |
| Niobium, Nb |
4.7 |
| Titanium, Ti |
1.5 |
| Silicon, Si |
0.15 |
| Aluminum, Al |
0.03 |
Physical Properties
The physical properties of Incoloy 907™ are given in the following table.
| Properties |
Metric |
Imperial |
| Density |
8.33 g/cm³ |
0.301 lb/in³ |
| Melting point |
1385°C |
2525°F |
Mechanical Properties
The mechanical properties of Incoloy 907™ are outlined in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength (precipitation hardened, value at room temperature) |
1350 MPa |
196000 psi |
| Yield strength (@ strain 0.200%, precipitation hardened, value at room temperature) |
1100 MPa |
160000 psi |
| Poisson’s ratio |
0.36 |
0.36 |
| Elongation at break (precipitation hardened) |
10% |
10% |
| Reduction of area |
36 |
36 |
Thermal Properties
The thermal properties of Incoloy 907™ are displayed in the following table.
| Properties |
Metric |
Imperial |
| Thermal expansion co-efficient (@ 20-427°C/68-801°F) |
7.70 µm/m°C |
4.28 µin/in°F |
| Thermal conductivity |
14.8 W/mK |
103 BTU in/hr. ft².°F |
Fabrication and Heat Treatment
Machinability
Incoloy 907™ can be machined using conventional machining methods which are used for iron-based alloys. Machining operations are performed using commercial coolants. High-speed operations such as grinding, milling or turning, are performed using water-base coolants.
Forming
Incoloy 907™ can be formed using all conventional techniques.
Welding
Incoloy 907™ is welded using gas-tungsten arc welding, shielded metal-arc welding, gas metal-arc welding, and submerged-arc welding methods.
Heat Treatment
Incoloy 907™ is heat treated by annealing at 983°C (1800°F).
Forging
Incoloy 907™ is forged at 927 to 1149°C (1700 to 2100°F).
Hot Working
Incoloy 907™ is hot worked at 885 to1149°C (1650 to 2100°F).
Cold Working
Incoloy 907™ is cold worked using standard tooling.
Annealing
Annealing of Incoloy 907™ is done at 983°C (1800°F) followed by cooling in air.
Aging
Incoloy 907™ is aged at 719°C (1325°F) for 8 h followed by cooling to attain maximum tensile properties. It is aged at 774°C (1425°F) for 12 h followed by cooling to attain maximum hot rupture strength.
Applications
Incoloy 907™ is used in the following applications:
- Gas turbine seals
- Casings
- Glass to metal sealing