Super Alloy Nicrofer 4722 Co (UNS N06002)

Topics Covered

Introduction
Chemical Composition
Physical Properties
Other Designations
Fabrication and Heat Treatment
     Machinability
     Forming
     Welding
     Heat Treatment
     Forging
     Cold Working
     Aging
Applications

Introduction

Super alloy Nicrofer 4722 Co is a wrought nickel-based alloy with excellent high temperature strength, excellent oxidation resistance, and good resistance to stress-corrosion cracking.

The following sections will discuss in detail about super alloy Nicrofer 4722 Co.

Chemical Composition

The chemical composition of Nicrofer 4722 Co is outlined in the following table.

Element Content (%)
Chromium, Cr 20.5 - 23
Iron, Fe 17 - 20
Molybdenum, Mo 8-10
Silicon, Si 1 max
Manganese, Mn 1 max
Cobalt, Co 0.5 - 2.5
Copper, Cu 0.5 max
Aluminum, Al 0.5 max
Tungsten, W 0.2 - 1
Titanium, Ti 0.15 max
Carbon, C 0.05 - 0.15
Phosphorus, P 0.04 max
Sulfur, S 0.03 max
Boron, b 0.008 max
Nickel, Ni Remainder

Physical Properties

The physical properties of Nicrofer 4722 Co are tabulated below.

Properties Metric Imperial
Density 8.2 g/cm3 0.297 lb/in3
Melting point 1315°C 2400°F

Other Designations

Equivalent materials to Nicrofer 4722 Co are listed below:

AMS 5588 ASTM B572 ASTM B626 GE B50A463 GE B50TF31
AMS 5587 ASTM B435 ASTM B622 DIN 2.4665 GE B50TF24
AMS 5536 AMS 5798 ASTM B619 GE B50A436 GE B50TF25
AISI 680 AMS 5754 ASTM B366 DIN 2.4603 GE B50T83A

Fabrication and Heat Treatment

Machinability

Super alloy Nicrofer 4722 Co can be machined using the common processes applied to austenitic 300 series stainless steels.

Forming

Super alloy Nicrofer 4722 Co can be cold formed using conventional tooling and methods.

Welding

Welding of super alloy Nicrofer 4722 Co can be performed using traditional welding methods such as shielded metal arc, resistance welding, and MIG or TIG. Matching alloy filler metal is required. Preheating and/or post heating are not required.

Heat Treatment

Super alloy Nicrofer 4722 Co can be solution annealed at 1176°C (2150° F) followed by rapid cooling.

Forging

Hot forging can be performed using conventional methods.

Cold Working

Nicrofer 4722 Co can be easily cold worked in the same manner as austenitic 300 series stainless steels. The only difference being that this alloy is comparatively stiffer and may require more pressure.

Aging

Nicrofer 4722 Co can be aged after solution heat treatment at temperatures of 649 to 871°C (1200 to 1600 F). Aging will result in a slight increase in strength and hardness with the effect being related to hours of exposure at the aging temperature - the longer the time the greater the effect.

Applications

Nicrofer 4722 Co is used found in the following applications areas:

  • Petrochemical process equipment and gas turbines in the hot combustor zone sections
  • Structural components in industrial furnace applications

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