Jul 25 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
Machinability
Forming
Welding
Heat Treatment
Forging
Hot Working
Cold Working
Annealing
Hardening
Other Designations
Applications
Introduction
Pyromet 718 is a precipitation hardenable nickel-base alloy that exhibits exceptionally high yield, tensile and creep-rupture properties at temperatures up to 704°C (1300°F). The alloy allows annealing and welding without spontaneous hardening during heating and cooling. It has excellent weldability when compared to the nickel-base superalloys.
The following section will provide an overview of Pyromet 718 alloy.
Chemical Composition
The chemical composition of Pyromet 718 alloy is outlined in the following table.
|
Element |
Content (%) |
|
Nickel, Ni |
50 - 55 |
|
Chromium, Cr |
17-21 |
|
Niobium, Nb |
4.75-5.5 |
|
Molybdenum, Mo |
2.8-3.3 |
|
Cobalt, Co |
1 |
|
Titanium, Ti |
0.65-1.15 |
|
Silicon, Si |
0.35 |
|
Manganese, Mn |
0.35 |
|
Copper, Cu |
0.3 |
|
Aluminum, Al |
0.2-0.8 |
|
Carbon, C |
0.08 |
|
Sulfur, S |
0.015 |
|
Phosphorus, P |
0.015 |
|
Boron, B |
0.006 |
|
Iron, Fe |
Balance |
Physical Properties
The following table shows the physical properties of Pyromet 718 alloy.
|
Properties |
Metric |
Imperial |
|
Density |
8.22 g/cm3 |
0.297 lb/in3 |
|
Melting point |
1204-1343°C |
2200-2450°F |
Mechanical Properties
The mechanical properties of Pyromet 718 alloy are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile strength (Precipitation hardened) |
1375 MPa |
199400 psi |
|
Yield strength (Precipitation hardened) |
1100 MPa |
160000 psi |
|
Elongation at break (Precipitation hardened) |
25% |
25% |
Thermal Properties
The thermal properties of Pyromet 718 alloy are given in the following table
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@20-100°C/68-212°F) |
13 µm/m°C |
7.22 µin/in°F |
|
Thermal conductivity |
11.4 W/mK |
79.1 BTU.in/hrft².°F |
Fabrication and Heat Treatment
Machinability
Pyromet 718 alloy can be machined using conventional machining techniques used for iron based alloys.
Forming
This alloy has good ductility, and hence it can be formed using all conventional methods.
Welding
Pyromet 718 alloy can be welded using gas-tungsten arc welding, shielded metal arc welding, submerged-arc welding and gas metal-arc welding methods.
Heat Treatment
This alloy is age-hardenable, and can be heat-treated at (1900°F) followed by air cooling.
Forging
Forging of Pyromet 718 alloy is carried out in the range of (1700 to 2050°F).
Hot Working
This alloy can be hot-worked in the temperature ranging from (1650 to 2050°F).
Cold Working
The alloy can be cold-worked using standard tooling.
Annealing
Annealing of Pyromet 718 alloy can be performed at 1900°F followed by air cooling.
Hardening
The alloy can be hardened using cold working techniques.
Other Designations
Other designations that are equivalent to Pyromet 718 alloy include the following:
|
AMS 5589 |
ASTM B637 |
GE B50TF15 |
|
AMS 5590 |
ASTM B670 |
PWA 1009 |
|
AMS 5596 |
DIN 2.4668 |
PWA 1010 |
|
AMS 5597 |
DIN 2.4688 |
PWA 1033 |
|
AMS 5662 |
GE B14H89 |
RBO 170-153 |
|
AMS 5663 |
GE B50 TF14 |
SPS M275 |
|
AMS 5664 |
GE B50 TF69 |
SPS M637 |
AMS 5832
|
GE B50TF14
|
|
Applications
The following are the list of applications of Pyromet 718 alloy:
-
Gas turbines
-
Turbo pump seals
-
Spacecraft
-
Rocket motors
-
Nuclear reactors
-
Tooling