Nov 22 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Cold Working
Annealing
Applications
Introduction
Super alloys are also called high performance alloys. They contain a number of elements in a variety of combinations to reach the desired result. These alloys can function in environments with high temperatures and severe mechanical stress, and also in cases where high surface stability is needed. Super alloys have good creep and oxidation resistance.
Strengthening of super alloys is performed by work hardening, solid-solution hardening, and precipitation hardening methods.
Nimonic Alloy 263™ is a British nickel-chromium-cobalt-molybdenum alloy specially meant for use in high temperature and high strength applications. This alloy can be precipitation-hardened.
The following datasheet will provide more details about Nimonic Alloy 263™.
Chemical Composition
The following table shows the chemical composition of Nimonic Alloy 263™.
|
Element |
Content (%) |
|
Nickel, Ni |
49 |
|
Cobalt, Co |
19-21 |
|
Chromium, Cr |
19-21 |
|
Molybdenum, Mo |
5.60-6.10 |
|
Titanium, Ti |
1.90-2.40 |
|
Iron, Fe |
0.70 |
|
Manganese, Mn |
0.60 |
|
Aluminum, Al |
0.60 |
|
Silicon, Si |
0.40 |
|
Copper, Cu |
0.20 |
|
Carbon, C |
0.040 - 0.080 |
|
Boron, B |
0.0050 |
|
Sulfur, S |
0.0070 |
Physical Properties
The physical properties of Nimonic Alloy 263™ are outlined in the following table.
|
Properties |
Metric |
Imperial |
|
Density |
8.36 g/cm³ |
0.302 lb/in³ |
|
Melting point |
1300-1355°C |
2370-2471°F |
Mechanical Properties
The mechanical properties of Nimonic Alloy 263™ are provided below.
|
Properties |
Metric |
Imperial |
|
Tensile strength (precipitation hardened, value at room temperature) |
940 MPa |
136000 psi |
|
Yield strength (@strain 0.200%, precipitation hardened, value at room temperature) |
550 MPa |
79800 psi |
|
Elongation at break (precipitation hardened) |
39% |
39% |
Thermal Properties
The thermal properties of Nimonic Alloy 263™ are given below.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@21-100°C/69.8-212°F) |
10.3 µm/m°C |
5.72 µin/in°F |
|
Thermal conductivity |
11.7 W/mK |
81.2 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to Nimonic Alloy 263™ are listed below:
-
AMS 5872
-
AMS 5886
-
DIN 2.4650
Fabrication and Heat Treatment
Machinability
Traditional machining methods that are used for iron-based alloys can be used for Nimonic Alloy 263™. Before cutting is performed, it is recommended that heavy duty machining equipment and tooling be used so as to reduce chatter or work-hardening of the alloy. During high speed operations such as grinding, turning, or milling, water-base coolants are preferred. The use of heavy lubricants while drilling, tapping, broaching or boring is recommended.
Forming
Nimonic Alloy 263™ has good ductility and can be easily formed using all the conventional methods. This alloy is stronger than regular steel; hence it requires a more powerful equipment to complete the forming process. It is recommended that heavy-duty lubricants should be used while cold forming. At the end of this process, all traces of lubricant has to be cleaned off to prevent embrittlement.
Welding
Nimonic Alloy 263™ can be welded using the traditional welding methods. Some of the commonly used methods are shielded metal-arc welding, gas metal-arc welding, submerged-arc welding, and gas-tungsten arc welding. It is recommended that matching alloy filler metal should be used. Before the welding process begins, the surface to be welded should be cleaned and should be free from oil, paint or crayon stains.
Heat Treatment
Nimonic Alloy 263™ can be solution annealed at 1149°C (2100°F) and rapidly cooled by using the water quench method. It can then be precipitation-hardened at 799°C (1470°F) for 24 h, which can be followed by air cooling.
Cold Working
Cold working can be performed using standard tooling. It is better to avoid using plain carbon tool steels for forming as they cause galling. To minimize galling and provide a neat finish, soft die materials containing bronze and zinc alloys are recommended. However, the life of the die is short. Likewise, heavy duty lubricants should be used to reduce galling in all forming operations.
Annealing
Nimonic Alloy 263™ can be solution annealed at 1149°C (2100°F) and then water quenched.
Applications
Nimonic Alloy 263™ is mainly used in gas turbine hot section components.