Nov 14 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Forging
Hot Working
Cold Working
Applications
Introduction
Super alloys are also called high performance alloys. They can
function under elevated temperatures and extreme mechanical stress, and
also where high surface stability is required. They also have good
creep and oxidation resistance.
Super alloys have many elements in a variety of combinations
so as to achieve the desired result. Strengthening of super alloys is
performed by solid-solution hardening, work hardening, and
precipitation hardening methods.
There are three types of alloys, namely cobalt-base,
nickel-base, and iron-base. All of these can be used at temperatures
above 540°C (1000°F).
Super alloy AL 800™ is a nickel-chromium-iron alloy capable of
resisting high temperature oxidation.
The following datasheet will provide more details about super
alloy AL 800™.
Chemical Composition
The following table shows the chemical composition of super
alloy AL 800™.
| Element |
Content
(%) |
| Iron, Fe |
44.5 |
| Nickel, Ni |
32 |
| Chromium, Cr |
21 |
| Manganese, Mn |
1 |
| Aluminum, Al |
0.4 |
| Titanium, Ti |
0.4 |
| Silicon, Si |
0.35 |
| Copper, Cu |
0.3 |
| Carbon, C |
0.02 |
| Phosphorous, P |
0.02 |
| Sulfur, S |
0.01 |
Physical Properties
The physical properties of super alloy AL 800™ are outlined in
the following table.
| Properties |
Metric |
Imperial |
| Density |
8.08 g/cm³ |
0.292 lb/in³ |
| Melting point |
1371°C |
2500°F |
Mechanical Properties
The mechanical properties of super alloy AL 800™ are provided
below.
| Properties |
Metric |
Imperial |
| Tensile strength
(typical annealed at 982°C/1800°F) |
600 MPa |
87000 psi |
| Yield strength
(typical annealed at 982°C/1800°F, at strain 0.200%) |
295 MPa |
42800 psi |
| Elongation at break
(typical annealed at 982°C/1800°F, in 2") |
44% |
44% |
| Hardness, Rockwell B
(typical annealed) |
70 |
70 |
Other Designations
Equivalent materials to super alloy AL 800™ are provided in
the table below.
| AMS 5766 |
AMS 5871 |
ASTM B163 |
ASTM B366 |
| ASTM B408 |
ASTM B409 |
ASTM B514 |
ASTM B515 |
| DIN 1.4876 |
ASTM B407 |
ASTM B564 |
|
Fabrication and Heat
Treatment
Machinability
Traditional machining methods used for iron-based alloys can
be used for super alloy AL 800™. During high-speed operations such as
turning, grinding, or milling, it is recommended that water-based
coolants are used. The use of heavy lubricants is suitable for
drilling, tapping, broaching or boring operations. In cases where
turning with a continuous cut is performed, carbide tools are suitable.
Forming
Super alloy AL 800™ can be formed using conventional methods
as it has good ductility. Powerful equipment is required.
Welding
Super alloy AL 800™ is weldable using all the conventional
methods. Some of the commonly used methods are gas-tungsten arc
welding, shielded metal-arc welding, gas metal-arc welding and
submerged-arc welding. It is recommended that matching alloy filler
metal should be used. Before the welding process begins, the surface to
be welded should be cleaned and should be free from oil, paint or
crayon stains.
Forging
Forging of super alloy AL 800™ should be performed in the
range of 1232-1010°C (2250-1850°F).
Hot Working
Super alloy AL 800™ can be hot worked in the range of
1204-871°C (2200-1600°F).
Cold Working
Super alloy AL 800™ can be cold worked using conventional
tooling. To minimize galling and provide a neat finish, soft die
materials containing bronze and zinc alloys are recommended. However,
the life of the die is short.
Applications
Super alloy AL 800™ is used in the following:
- Heat treating equipment and fittings
- Sheathing for electric resistance alloy tubular heating
elements
- Heat exchangers.