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
Annealing
Applications
Introduction
Super alloys are also called high performance alloys. They
function well under very high temperatures and extreme mechanical
stress, and also where high surface stability is required. They have
good creep and oxidation resistance.
Super alloys contain many elements in a variety of
combinations. 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 800H™ is a modified version of Incoloy 800 with
better creep and rupture strength. This is because of the closely
controlled carbon content and improved heat treatment.
The following datasheet will provide more details about super
alloy AL 800H™.
Chemical Composition
The following table shows the chemical composition of super
alloy AL 800H™.
| Element |
Content
(%) |
| Iron, Fe |
44 |
| 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 |
0.08 |
| Phosphorous, P |
0.02 |
| Sulfur, S |
0.01 |
Physical Properties
The physical properties of super alloy AL 800H™ 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 800H™ are provided
below.
| Properties |
Metric |
Imperial |
| Tensile strength
(typical annealed at 1149°C/2100°F) |
531MPa |
77000 psi |
| Yield strength
(typical annealed at 1149°C/2100°F, @strain 0.200%) |
200 MPa |
29000 psi |
| Elongation at break
(typical annealed at 1149°C/2100°F, in 2") |
52% |
52% |
| Hardness, Rockwell B
(typical annealed) |
70 |
70 |
Other Designations
Equivalent materials to super alloy AL 800H™ are provided in
the table below.
| ASTM B163 |
ASTM B407 |
ASTM B408 |
ASTM B409 |
| ASTM B514 |
ASTM B564 |
DIN 1.4876 |
DIN 1.4958 |
Fabrication and Heat
Treatment
Machinability
Traditional machining methods used for iron-based alloys can
be used for super alloy AL 800H™. During high-speed operations such as
turning, grinding, or milling, it is recommended that water-based
coolants are used. The use of heavy lubricants for drilling, tapping,
broaching or boring operations is suitable. In cases where turning with
a continuous cut is performed, carbide tools are suitable.
Forming
Super alloy AL 800H™ can be formed using conventional methods
as it has good ductility. Powerful equipment is required.
Welding
Super alloy AL 800H™ 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 free from oil, paint or crayon stains.
Forging
Forging of super alloy AL 800H™ should be performed in the
range of 1204-982°C (2200-1800°F).
Hot Working
Super alloy AL 800H™ can be hot worked in the range of
1204-871°C (2200-1600°F).
Cold Working
Super alloy AL 800H™ 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.
Annealing
Super alloy AL 800H™ can be annealed at 1177°C (2150°F) and
then air cooled.
Applications
Super alloy AL 800H™ is used in the following:
- Piping for petrochemical plants
- Heaters and heat exchangers that are exposed to prolonged
high temperatures.