Jul 30 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Forging
Welding
Annealing
Hot Working
Cold Working
Aging
Applications
Introduction
Super alloy HAYNES 718 is a high-strength, high-temperature resistant and corrosion resistant nickel-chromium alloy. This alloy provides excellent high-temperature strength of up to 650°C (1202°F), formability, weldability, and good ductility. The following sections about super alloy HAYNES 718 will be discussed in detail below.
Chemical Composition
The chemical composition of HAYNES 718 is outlined in the following table.
|
Element |
Content (%) |
|
Nickel, Ni |
52 |
|
Iron, Fe |
19 |
|
Chromium, Cr |
18 |
|
Niobium, Nb |
5 |
|
Tantalum, Ta |
5 |
|
Molybdenum, Mo |
3 |
|
Cobalt, Co |
≤ 1 |
|
Titanium, Ti |
0.90 |
|
Aluminum, Al |
0.50 |
|
Manganese, Mn |
≤ 0.35 |
|
Silicon, Si |
≤ 0.35 |
|
Copper, Cu |
≤ 0.10 |
|
Carbon, C |
0.050 |
|
Boron, B |
0.0090 |
Physical Properties
The physical properties of HAYNES 718 are tabulated below.
|
Properties |
Metric |
Imperial |
|
Density |
8.23 g/cm3 |
0.297 lb/in3 |
Mechanical Properties
The following table shows mechanical properties of HAYNES 718.
|
Properties |
Metric |
Imperial |
|
Tensile strength |
1395 MPa |
202300 psi |
|
Yield strength |
1175 MPa |
170400 psi |
|
Elastic modulus |
200 GPa |
29000 ksi |
|
Elongation at break |
22.3 % |
22.3 % |
Thermal Properties
The thermal properties of HAYNES 718 are tabulated below.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (at 25-200°C/77-392°F) |
12.8 µm/m°C |
7.11 µin/in°F |
|
Thermal conductivity |
11.4 W/mK |
79.1 BTU in/hr.ft².°F |
Other Designations
Equivalent materials to HAYNES 718 are tabulated below:
|
AMS 5589 |
AMS 5832 |
ASTM B637 |
GE B50TF14 |
GE B50TF15 |
|
AMS 5590 |
AMS 5664 |
ASTM B670 |
GE B50 TF69 |
PWA 1009 |
|
AMS 5596 |
AMS 5663 |
DIN 2.4668 |
GE B14H89 |
PWA 1010 |
|
AMS 5597 |
AMS 5662 |
DIN 2.4688 |
GE B50 TF14 |
PWA 1033 |
|
RBO 170-153 |
SPS M275 |
SPS M637 |
|
|
Fabrication and Heat Treatment
Machinability
HAYNES 718 can be machined using the common processes used for iron based alloys. The material work hardens during machining and has higher strength and gumminess. It is recommended that heavy duty machining equipment and tooling be used to reduce chatter. Commonly available commercial coolants can be used for the process.
Forming
HAYNES 718 can be readily formed using all the traditional methods. As this alloy has high strength, powerful equipment has to be used. It is important that the material is properly cleaned of all traces of lubricant after forming to prevent embrittlement from occurring.
Forging
Forging can be done at 1121-926°C (2050-1700°F).
Welding
Welding of HAYNES 718 can be performed using all the traditional welding methods. It is recommended that a matching alloy filler metal be used. Preheating is not required. The surfaces to be welded have to be free from oil, paint or crayon markings.
Annealing
Annealing of the material can be performed at 1037°C (1900°F) and then rapidly air cooled.
Hot Working
Hot working can be performed by heating the alloy to 1121-899°C (2050-1650°F). The alloy has to be reheated if hot working temperatures drop below 899°C (1650°F).
Cold Working
HAYNES 718 can be cold worked using all the traditional methods and tooling.
Aging
For aging HAYNES 718, anneal at 982°C (1800°F) and age at 718°C (1325°F) for 8 h. This should be followed by furnace cooling to 621°C (1150°F) and holding at that temperature for 10 h, and then air cooled.
Applications
HAYNES 718 is used in the following application areas:
-
Cryogenic storage tanks
-
Gas turbine hot section components
-
Fasteners and instrumentation parts
-
Various components for oil/gas well down holes and well heads
-
Aircraft and land-based turbine engine components such as rings, casings, and formed sheet metal components.