Jul 30 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Hot Working
Forging
Cold Working
Annealing
Hardening
Applications
Introduction
Super alloys are high performance alloys meant for use in high temperature environments. They are strong and resist corrosion very well. Super alloy Nicrofer 4221 is a Ni-Cr-Fe alloy with additions of other alloying elements that is built specifically to resist chemical corrosion.
The following sections will discuss in detail about super alloy Nicrofer 4221.
Chemical Composition
The chemical composition of Nicrofer 4221 is outlined in the following table.
|
Element |
Content (%) |
|
Nickel, Ni |
38 - 46 |
|
Chromium, Cr |
19.5 - 23.5 |
|
Molybdenum, Mo |
2.5 - 3.5 |
|
Copper, Cu |
1.5 - 3 |
|
Manganese, Mn |
1 max |
|
Titanium, Ti |
0.6 - 1.2 |
|
Silicon, Si |
0.5 max |
|
Aluminum, Al |
0.2 max |
|
Carbon, C |
0.05 max |
|
Sulfur, S |
0.03 max |
|
Phosphorus, P |
0.03 max |
|
Iron, Fe |
Remainder |
Physical Properties
The physical properties of Nicrofer 4221 are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
8.13 g/cm3 |
0.294 lb/in3 |
|
Melting point |
1385°C |
2525°F |
Other Designations
Equivalent materials to Nicrofer 4221 are listed below:
-
ASTM B163
-
ASTM B423
-
ASTM B424
-
ASTM B425
-
ASTM B564
-
ASTM B704
-
ASTM B705
-
DIN 2.4858
Fabrication and Heat Treatment
Machinability
Super alloy Nicrofer 4221 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 common commercial coolant can be used during the machining operations. In case of high speed operations such as grinding, turning, or milling, it is best to use water-based coolants. Likewise it is advisable to use heavy lubricants for drilling, broaching, tapping, or boring.
Forming
Super alloy Nicrofer 4221 can be formed using any of the conventional methods as it is ductile. Since this alloy is stronger than regular steel it will requires a more powerful equipment to perform forming.
Welding
Welding of super alloy Nicrofer 4221 can be performed using all the traditional welding methods. 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. The weld beads should be slightly convex. Pre-heating is not required.
Hot Working
Hot working can be performed at temperatures less than 926°C (1700°F).
Forging
Forge at temperatures in the range of 1093-982°C (2000-1800°F). A final anneal is required to be performed at 954°C (1750°F) so as to regain optimum corrosion properties.
Cold Working
Nicrofer 4221 can be cold worked using all the standard tools.
Annealing
Nicrofer 4221 can be annealed at 954°C (1750°F) and rapidly cooled.
Hardening
Super alloy Nicrofer 4221 hardens only by cold work.
Applications
Nicrofer 4221 is used found in the following applications areas:
-
Pickling
-
Chemical process equipment
-
Acid production piping and vessels.