Introduction
Super alloys have the ability to function at very high temperatures and mechanical stress, and also where high surface stability is required. They have good creep and oxidation resistance, and can be produced in a variety of shapes. They can be strengthened by solid-solution hardening, work hardening, and precipitation hardening.
Super alloys consist of a number of elements in a variety of combinations to achieve the desired result. They are further classified into three groups such as cobalt-based, nickel-based, and iron-based alloys.
Incoloy(r) alloy 825 is an austenitic nickel-iron-chromium alloy which is added with other alloying elements in order to improve its chemical corrosion resistant property. The following datasheet will provide more details about Incoloy(r) alloy 825.
Chemical Composition
The following table shows the chemical composition of Incoloy(r) alloy 825
|
Element |
Content (%) |
|
Nickel, Ni |
38-46 |
|
Iron, Fe |
22 |
|
Chromium, Cr |
19.5-23.5 |
|
Molybdenum, Mo |
2.50-3.50 |
|
Copper, Cu |
1.50-3.0 |
|
Manganese, Mn |
1 |
|
Titanium, Ti |
0.60-1.20 |
|
Silicon, Si |
0.50 |
|
Aluminum, Al |
0.20 |
|
Carbon, C |
0.050 |
|
Sulfur, S |
0.030 |
Chemical Composition
The following table shows the chemical composition of Incoloy(r) alloy 825.
| Element | Content (%) |
| Nickel, Ni | 38-46 |
| Iron, Fe | 22 |
| Chromium, Cr | 19.5-23.5 |
| Molybdenum, Mo | 2.50-3.50 |
| Copper, Cu | 1.50-3.0 |
| Manganese, Mn | 1 |
| Titanium, Ti | 0.60-1.20 |
| Silicon, Si | 0.50 |
| Aluminum, Al | 0.20 |
| Carbon, C | 0.050 |
| Sulfur, S | 0.030 |
Physical Properties
The physical properties of Incoloy(r) alloy 825 are given in the following table.
|
Properties |
Metric |
Imperial |
|
Density |
8.14 g/cm³ |
0.294 lb/in³ |
|
Melting point |
1385°C |
2525°F |
Mechanical Properties
The mechanical properties of Incoloy(r) alloy 825 are highlighted in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile strength (annealed) |
690 MPa |
100000 psi |
|
Yield strength (annealed) |
310 MPa |
45000 psi |
|
Elongation at break (annealed prior to test) |
45% |
45% |
Thermal Properties
The thermal properties of Incoloy(r) alloy 825 are outlined in the following table.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (at 20-100°C/68-212°F) |
14 µm/m°C |
7.78 µin/in°F |
|
Thermal conductivity |
11.1 W/mK |
77 BTU in/hr.ft².°F |
Other Designations
Other designations that are equivalent to Incoloy(r) alloy 825 include:
- ASTM B163
- ASTM B423
- ASTM B424
- ASTM B425
- ASTM B564
- ASTM B704
- ASTM B705
- DIN 2.4858
Fabrication and Heat Treatment
Machinability
Incoloy(r) alloy 825 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-based coolants.
Forming
Incoloy(r) alloy 825 can be formed using all conventional techniques.
Welding
Incoloy(r) alloy 825 is welded using gas-tungsten arc welding, shielded metal-arc welding, gas metal-arc welding, and submerged-arc welding methods.
Heat Treatment
Incoloy(r) alloy 825 is heat treated by annealing at 955°C (1750°F) followed by cooling.
Forging
Incoloy(r) alloy 825 is forged at 983 to 1094°C (1800 to 2000°F).
Hot Working
Incoloy(r) alloy 825 is hot worked below 927°C (1700°F).
Cold Working
Standard tooling is used for cold working Incoloy(r) alloy 825.
Annealing
Incoloy(r) alloy 825 is annealed at 955°C (1750°F) followed by cooling.
Hardening
Incoloy(r) alloy 825 is hardened by cold working.
Applications
Incoloy(r) alloy 825 is used in the following applications:
- Acid production piping
- Vessels
- Pickling
- Chemical process equipment.