Jul 9 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
Machinability
Hot Forming
Heat Treatment
Applications
Introduction
Super alloys are also known as high performance alloys specially designed to cater to environments with very high temperature of above 540°C (1000°F) where deformation resistance and high surface stability are essential.
Super alloy INCONEL 783 is a nickel-cobalt-iron alloy with chromium, aluminum, and niobium additions. It has oxidation-resistance, low coefficient of thermal expansion.
This alloy can be strengthened by a precipitation-hardening heat treatment. The presence of aluminum provides this alloy excellent resistance to oxidation at high temperature.
The following section explains in detail about super alloy INCONEL 783.
Chemical Composition
The chemical composition of INCONEL 783 is outlined in the following table.
|
Element |
Content (%) |
|
Nickel, Ni |
26-30 |
|
Iron, Fe |
24-27 |
|
Aluminum, Al |
5-6 |
|
Chromium, Cr |
2.5-3.5 |
|
Niobium, Nb |
2.5-3.5 |
|
Copper, Cu |
0.50 max |
|
Manganese, Mn |
0.50 max |
|
Silicon, Si |
0.50 max |
|
Titanium, Ti |
0.10-0.40 |
|
Carbon, C |
0.03 max |
|
Boron, B |
0.003-0.012 |
|
Phosphorus, P |
0.015 max |
|
Sulfur, S |
0.005 max |
|
Cobalt, Co |
Balance |
Physical Properties
The physical properties of INCONEL 783 are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
7.81 g/cm3 |
0.282 lb/in3 |
|
Melting point |
1336-1407 °C |
2437-2565 °F |
Mechanical Properties
The following table shows mechanical properties of INCONEL 783.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
1194 MPa |
171 ksi |
|
Yield strength |
779 MPa |
113 ksi |
|
Poisson’s ratio |
0.31 |
0.31 |
|
Elastic modulus |
177.3 GPA |
25.72 ksi |
|
Elongation at break |
24% |
24% |
Thermal Properties
The thermal properties of INCONEL 783 are tabulated below.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@93°C/200°F) |
10.08 µm/m°C |
5.60 µin/in°F |
|
Thermal conductivity (@21°C/70°F) |
10.1 W/m-°C |
71 BTU in/hr.ft².°F |
Fabrication and Heat Treatment
INCONEL 783 has good fabricability and can be formed, machined, and welded using all the traditional procedures for nickel alloys. This alloy’s reactions are similar to that of INCONEL 718.
Machinability
INCONEL 783 can be readily machined using the conventional practices for high-strength nickel alloys. In case of rough machining, the material has to be machined in the annealed condition.
Hot Forming
The temperature range for hot forming of INCONEL 783 is from 927°C to 1121°C (1700°F to 2050°F).
Heat Treatment
To heat treat this super alloy, the material has to solution annealed at 1121°C (2050°F) for 1 h, and air cooled. This should be followed by beta aging at 845°C (1550°F) for 4 h and air cooled to room temperature. Next the material is age hardened at 720°C (1325°F) for 8 h, furnace cooled at 55°C (100°F) for 1 hr to 620°C (1150°F) for 8 h and air cooled.
Applications
INCONEL 783 is widely used in gas turbine applications.