Nov 19 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Forging
Hot Working
Cold Working
Annealing
Applications
Introduction
Super alloys are also referred to as high performance alloys. They can function at high temperatures and mechanical stress, and are formed in different shapes. They are strengthened by work hardening, solid-solution hardening, and precipitation hardening. There are three groups of alloys, namely cobalt-based, nickel-based, and iron-based super alloys.
Altemp 625™ is a nickel-chromium-molybdenum wrought alloy. It has an ability to withstand stress-corrosion cracking and intergranular attack. The following sections with discuss about Altemp 625™ in detail.
Chemical Composition
The chemical composition of Altemp 625™ is displayed in the following table.
|
Element |
Content (%) |
|
Nickel, Ni |
60 |
|
Chromium, Cr |
22 |
|
Molybdenum, Mo |
9 |
|
Iron, Fe |
4 |
|
Niobium, Nb |
3.5 |
|
Titanium, Ti |
0.3 |
|
Manganese, Mn |
0.3 |
|
Aluminum, Al |
0.3 |
|
Silicon, Si |
0.25 |
|
Carbon, C |
0.05 |
|
Sulfur, S |
0.003 |
|
Phosphorous, P |
0.01 |
Physical Properties
The physical properties of Altemp 625™ are highlighted in the following table.
|
Properties |
Metric |
Imperial |
|
Density |
8.44 g/cm³ |
0.305 lb/in³ |
|
Melting point |
1330°C |
2425°F |
Mechanical Properties
The following table shows the mechanical properties of Altemp 625™.
|
Properties |
Metric |
Imperial |
|
Hardness, Rockwell B (typical annealed) |
95 |
95 |
|
Tensile strength (for flat products (<4" thickness) and seamless tube and pipe) |
≥ 827 MPa |
≥ 120000 psi |
|
Yield strength (for flat products (<4" thickness) and seamless tube and pipe) |
≥ 414 MPa |
≥ 60000 psi |
|
Elongation at break (typical annealed) |
45% |
45% |
Other Designations
Other designations that are equivalent to Altemp 625™ are included in the following table.
|
AMS 5581 |
AMS 5837 |
ASTM B443 |
ASTM B704 |
GE B50TF133 |
|
AMS 5599 |
AMS 5879 |
ASTM B444 |
ASTM B705 |
MIL E-21562 (RN625) |
|
AMS 5666 |
ASTM B366 |
ASTM B446 |
DIN 2.4856 |
|
Fabrication and Heat Treatment
Machinability
Altemp 625™ can be machined using conventional methods.
Forming
Altemp 625™ can be formed using conventional methods.
Welding
Altemp 625™ is welded using conventional methods.
Heat Treatment
Altemp 625™ is heat treated in the solution annealed condition at 1177°C (2150°F) for an adequate period of time depending on thickness of a section.
Forging
Altemp 625™ is forged at 1149 to 1177°C (2100 to 2150°F).
Hot Working
Altemp 625™ is hot worked at 1177°C (2150°F).
Cold Working
Cold working of Altemp 625™ is done using tooling and conventional methods
Annealing
Altemp 625™ is annealed at 983 to 1094°C (1800 to 2000°F) followed by cooling.
Applications
Altemp 625™ is suitable for high temperature applications such as gas turbine components and heat exchangers. It is also used in few acid process equipments and wet scrubbers due to its high corrosion resistance.