Jul 9 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Fabrication and Heat Treatment
Machinability
Welding
Heat Treatment
Forging
Hot Working
Cold Working
Annealing
Hardening
Other Designations
Applications
Introduction
Pyromet 625 alloy is a nonmagnetic, corrosion- and oxidation-resistant, nickel-base alloy with outstanding strength and toughness in high temperatures up to 1093°C (2000°F). The alloy has excellent stress-corrosion cracking resistance to chloride ions and fatigue strength.
The following section will provide an overview of Pyromet 625 alloy.
Chemical Composition
The chemical composition of Pyromet 625 alloy is outlined in the following table.
|
Element |
Content (%) |
|
Chromium,Cr |
20-23 |
|
Molybdenum, Mo |
8-10 |
|
Iron, Fe |
5 |
|
Niobium, Ni |
3.15-4.15 |
|
Cobalt, Co |
1 |
|
Silicon, Si |
0.5 |
|
Manganese, Mn |
0.5 |
|
Titanium, Ti |
0.4 |
|
Aluminum, Al |
0.4 |
|
Carbon, C |
0.1 |
|
Phosphorus, P |
0.015 |
|
Sulfur, S |
0.015 |
Physical Properties
The following table shows the physical properties of Pyromet 625 alloy.
|
Properties |
Metric |
Imperial |
|
Density |
8.44 g/cm3 |
0.305 lb/in3 |
|
Melting point |
1329°C |
2425°F |
Mechanical Properties
The mechanical properties of Pyromet 625 alloy are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile strength (annealed) |
880 MPa |
128000 psi |
|
Yield strength (annealed) |
460 MPa |
66700 psi |
|
Elongation at break (annealed prior to test) |
50% |
50% |
Thermal Properties
The thermal properties of Pyromet 625 alloy are given in the following table
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (@20-100°C/68-212°F) |
12.8 µm/m°C |
7.11 µin/in°F |
|
Thermal conductivity |
9.8 W/mK |
68 BTU.in/hrft².°F |
Fabrication and Heat Treatment
Machinability
Pyromet 625 alloy can be machined by conventional means. However, rigid tooling is required to prevent chatter and work hardening in front of the tool edge.
Welding
The alloy can be readily welded using alloy filler metal.
Heat Treatment
The alloy is heat treated at 1177°C (2150°F) and then air cooled.
Forging
Hot forging can be carried out by heating the alloy at 1149 to 1177°C (2100 to 2150°F).
Hot Working
The alloy may be hot worked at 1177°C (2150°F).
Cold Working
The alloy can be cold formed by conventional means and tooling.
Annealing
Annealing of Pyromet 625 alloy can be performed 982 to 1093°C (1800 to 2000°F) and air cooled.
Hardening
The strength of the alloy can be improved by cold working.
Other Designations
Other designations that are equivalent to Pyromet 625 alloy include the following:
-
MIL E-21562
-
GE B50TF133
-
DIN 2.4856
-
ASTM B366
-
ASTM B443
-
ASTM B444
-
ASTM B446
-
ASTM B704
-
ASTM B705
-
AMS 5581
-
AMS 5599
-
AMS 5666
-
AMS 5837
-
AMS 5879
Applications
The following are the list of applications of Pyromet 625 alloy:
-
Heat shields
-
Furnace hardware
-
Gas turbine engine ducting
-
Chemical plant hardware and special seawater applications
-
Combustion liners and spray bars
-
Aerospace and marine engineering.