Nov 20 2012
Topics Covered
IntroductionChemical CompositionPhysical PropertiesMechanical PropertiesOther DesignationsFabrication and Heat Treatment Machinability Forming Welding Forging Cold Working Annealing HardeningApplications
Introduction
Super alloys or high performance alloys are used at environments with very high temperature above 540ºC(1000ºF) where deformation resistance and high surface stability are chiefly required. They have good oxidation and creep resistance. Cobalt-base, nickel-base and iron-base alloys are the three major types of super alloys. The iron-base super alloys are generally wrought alloys provided with stainless steel technology. Nickel-base and cobalt-base super alloys may be cast or wrought based on its composition or application. Super alloys can be generally forged, rolled to sheet or produced in different shapes. Highly alloyed compositions are formed as castings. They can be strengthened using hardening techniques like work hardening, solid-solution hardening and precipitation hardening.
Super alloy HAYNES(r) 556 alloy™ has good strength and carburization and oxidation resistance at elevated temperatures. It also has excellent welding and forming characteristics.
The following section will discuss in detail about super alloy HAYNES(r) 556 alloy™.
Chemical Composition
The following table shows the chemical composition of super alloy HAYNES(r) 556 alloy™.
| Elements |
Content (%) |
| Iron, Fe |
31 |
| Chromium, Cr |
22 |
| Nickel, Ni |
20 |
| Cobalt, Co |
18 |
| Molybdenum, Mo |
3 |
| Tungsten, W |
2.5 |
| Manganese, Mn |
1 |
| Tantalum, Ta |
0.6 |
| Silicon, Si |
0.4 |
| Nitrogen, N |
0.2 |
| Aluminum, Al |
0.2 |
| Carbon, C |
0.1 |
| Lanthanum, La |
0.02 |
| Zirconium, Zr |
0.02 |
Physical Properties
The physical properties of super alloy HAYNES(r) 556 alloy™ are given in the following table.
| Properties |
Metric |
Imperial |
| Density |
8.23 g/cm³ |
0.297 lb/in³ |
| Melting point |
1371ºC |
2500ºF |
Mechanical Properties
The mechanical properties of super alloy HAYNES(r) 556 alloy™ are displayed in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength |
815 MPa |
118000 psi |
| Yield strength |
410 MPa |
59500 psi |
| Charpy impact |
240 J |
177 ft.lb |
| Elongation at break |
47.70% |
47.70% |
| Elastic modulus |
205 GPa |
29700 ksi |
Other Designations
Other designations that are equivalent to super alloy HAYNES(r) 556 alloy™ include the following:
- AMS 5831
- AMS 5874
- AMS 5877
- ASTM B366
- ASTM B435
- ASTM B572
- ASTM B619
- ASTM B622
- ASTM B626
Fabrication and Heat Treatment
Machinability
HAYNES(r) 556 alloy™ can be machined using conventional techniques employed for iron based alloys. High speed operations like milling, grinding or turning can be performed using water-base coolants. Heavy lubricants are recommended for operations such as boring, broaching, tapping or drilling.
Forming
HAYNES(r) 556 alloy™ can be formed by conventional means. For cold forming this alloy, heavy-duty lubricants can be used.
Welding
Welding of HAYNES(r) 556 alloy™ is performed through commonly used welding techniques like gas tungsten arc welding, shielded metal-arc welding, metal-arc welding and submerged-arc welding. However, an alloy filler metal that suits this alloy should be used.
Forging
HAYNES(r) 556 alloy™ can be forged at temperatures ranging from 927 to 1177°C (1700 to 2150°F).
Cold Working
HAYNES(r) 556 alloy™ can be cold worked using standard tooling methods. As plain carbon steels has an ability to produce galling, they are not preferred for forming this alloy. Galling can be minimized with the help of soft die materials.
Annealing
HAYNES(r) 556 alloy™ can be annealed at 1177°C (2150°F) followed by rapid cooling of air and water quenching.
Hardening
HAYNES(r) 556 alloy™ can be hardened by cold working.
Applications
The following are the major applications of HAYNES(r) 556 alloy™:
- Incinerators
- Gas turbines
- Heat transfer systems