Super Alloy Nicrofer 5520 Co (UNS N06617)

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

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