Jul 24 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Forging
Hot Working
Cold Working
Annealing
Applications
Introduction
Nicrofer 5520 Co is a nickel-chromium-cobalt-molybdenum alloy with excellent mechanical and creep properties up to 1100°C (2000°F) due to solid solution hardening. It also possesses excellent resistance to oxidation and excellent resistance to carburization up to 1100°C (2000°F).
The following sections will discuss in detail about super alloy Nicrofer 5520 Co.
Chemical Composition
The chemical composition of Nicrofer 5520 Co is outlined in the following table.
|
Element |
Content (%) |
|
Chromium, Cr |
20 – 24 |
|
Cobalt, Co |
10-15 |
|
Molybdenum, Mo |
8-10 |
|
Iron, Fe |
3 max |
|
Silicon, Si |
1 max |
|
Manganese, Mn |
1 max |
|
Aluminum, Al |
0.8 - 1.5 |
|
Copper, Cu |
0.5 max |
|
Titanium, Ti |
0.2 - 0.5 |
|
Carbon, C |
0.05 - 0.15 |
|
Sulfur, S |
0.015 max |
|
Boron, B |
0.006 min |
|
Nickel, Ni |
Remainder |
Physical Properties
The physical properties of Nicrofer 5520 Co are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
8.4 g/cm3 |
0.303 lb/in3 |
|
Melting point |
1330-1380°C |
2430-2520°F |
Mechanical Properties
The following table shows mechanical properties of solution-treated sheet and strip Nicrofer 5520 Co.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
750 MPa |
109 ksi |
|
Yield strength |
350 MPa |
51 ksi |
|
Elongation |
35 |
35 |
Thermal Properties
The thermal properties of Nicrofer 5520 Co are tabulated below.
|
Properties |
Metric |
Imperial |
|
Thermal conductivity (@20°C/68°F) |
13.4 W/mK |
94 BTU in/hr.ft².°F |
Other Designations
Equivalent material to Nicrofer 5520 Co is DIN 2.4663.
Fabrication and Heat Treatment
Machinability
Super alloy Nicrofer 5520 Co can be machined using the common processes applied to iron based alloys. This alloy does work-harden during machining and displays higher strength and "gumminess" unlike steels. It is recommended that heavy duty machining equipment and tooling should be used to reduce chatter or work-hardening of the alloy.
Any commercial coolants can be used during the machining operations; however water-based coolants are recommended for high-speed operations such as milling, turning, or grinding. Similarly, heavy lubricants are ideal for tapping, broaching, drilling, or boring.
Forming
Super alloy Nicrofer 5520 Co can be formed using any of the conventional methods. Powerful equipment is required to perform forming operations as this alloy is strong.
Welding
Welding of super alloy Nicrofer 5520 Co can be performed using all the traditional welding methods as it is very ductile. Matching alloy filler metal should be used. In case that is not available, it is advised that the nearest alloy closest to the chemical composition be used.
Forging
Forging should be performed in the temperature range of 1204-1010°C (2200-1850°F).
Hot Working
Hot working can be performed in the temperature range of 1204-926°C (2200-1700°F).
Cold Working
Nicrofer 5520 Co can be cold formed using all the standard tools.
Annealing
Nicrofer 5520 Co can be solution annealed at 1176°C (2150°F) and rapidly cooled.
Applications
Nicrofer 5520 Co is widely used in many application areas as listed below:
-
Air heaters
-
Components for industrial and gas turbines such as housings, turbine rings, and combustion cans
-
Furnace muffles and radiant heater tubes
-
Equipment for the chemical process industry
-
Pigtails and furnace tubing in the petrochemical industry
-
High-temperature heat exchangers, valves, and spring
-
High-temperature gas-cooled nuclear reactors