Nov 15 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesOther DesignationsFabrication and Heat Treatment Machinability Forming Welding Heat Treatment Forging Hot Working Cold Working Annealing HardeningApplications
Introduction
Super alloys are also referred to as high performance alloys. They can be strengthened by work hardening, solid-solution hardening, and precipitation hardening. They have good creep and oxidation resistance, and can be formed in different shapes. They can function at very high temperatures and severe mechanical stress, and also where high surface stability is required. Nickel-based, iron-based, and cobalt-based alloys are three types of super alloys, and can be used at temperatures above 540°C (1000°F). The cobalt-based alloys have higher melting points than nickel-based or iron-based alloys, and can be strengthened by a combination of carbides and solid-solution hardeners.
Nicrofer 7520™ is a nickel-chromium alloy which is added with aluminum and titanium to increase its strength. The following datasheet gives an overview of Nicrofer 7520™.
Chemical Composition
The chemical composition of Nicrofer 7520™ is outlined in the following table.
| Element |
Content (%) |
| Chromium, Cr |
18-21 |
| Iron, Fe |
3 max |
| Titanium, Ti |
1.8-2.7 |
| Aluminum, Al |
1-1.8 |
| Silicon, Si |
1 max |
| Manganese, Mn |
1 max |
| Cobalt, Co |
0.2 max |
| Copper, Cu |
0.2 max |
| Carbon, C |
0.1 max |
| Phosphorus, P |
0.045 max |
| Boron, B |
0.008 max |
| Nickel, Ni |
Remainder |
Physical Properties
The physical properties of Nicrofer 7520™ are highlighted in the following table.
| Properties |
Metric |
Imperial |
| Density |
8.2 g/cm³ |
0.295 lb/in³ |
| Melting point |
1344°C |
2450°F |
Other Designations
Other designations that are equivalent to Nicrofer 7520™ include:
- ASTM B637
- DIN 2.4631
- DIN 2.4952
Fabrication and Heat Treatment
Machinability
Nicrofer 7520™ can be machined using conventional methods which are used for iron-based alloys. Machining operations are performed using commercial coolants. High-speed operations such as grinding, milling, or turning, are performed using water-base coolants. Heavy lubricants are used for boring, drilling, broaching or tapping.
Forming
Nicrofer 7520™ can be formed using all conventional techniques.
Welding
Nicrofer 7520™ is welded using shielded metal-arc welding, gas-tungsten arc welding, gas metal-arc welding, and submerged-arc welding methods.
Heat Treatment
Nicrofer 7520™ is heat treated by annealing at 1080°C (1975°F) for 8 h followed by cooling.
Forging
Nicrofer 7520™ is forged at 983 to 1177°C (1800 to 2150°F).
Hot Working
Nicrofer 7520™ is hot worked at temperatures ranging from 983 to 1177°C (1800 to 2150°F).
Cold Working
Nicrofer 7520™ can be cold worked using standard tooling.
Annealing
Nicrofer 7520™ is annealed at 1080°C (1975°F) for 8 h followed by cooling.
Hardening
Nicrofer 7520™ can be hardened by cold working.
Applications
Nicrofer 7520™ is mainly used in gas turbine hot section components.