Nov 16 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Forming
Welding
Forging
Hot Working
Cold Working
Annealing
Applications
Introduction
Super alloys have an ability to function under very high temperatures and severe mechanical stress, and also where high surface stability is required. They have good creep and oxidation resistance, and contain a number of elements in a variety of combinations so as to achieve the desired result. They are broadly classified into three groups such as cobalt-based, nickel-based, and iron-based alloys. All of these can be used at temperatures above 540°C (1000°F).
Inconel 751™ is a nickel-chromium alloy, and a modified version of Inconel X-750 alloy. The following datasheet gives more details about Inconel 751™.
Chemical Composition
The following table shows the chemical composition of Inconel 751™.
|
Elements |
Content (%) |
|
Nickel, Ni |
≥ 70 |
|
Chromium, Cr |
14-17 |
|
Iron, Fe |
5-9 |
|
Titanium, Ti |
2-2.60 |
|
Manganese, Mn |
≤ 1 |
|
Aluminum, Al |
0.90-1.50 |
|
Niobium, Nb |
0.70-1.20 |
|
Copper, Cu |
≤ 0.50 |
|
Silicon, Si |
≤ 0.50 |
|
Carbon, C |
≤ 0.10 |
|
Sulfur, S |
≤ 0.010 |
Physical Properties
The physical properties of Inconel 751™ are given in the following table.
|
Properties |
Metric |
Imperial |
|
Density |
8.22 g/cm³ |
0.297 lb/in³ |
|
Melting point |
1413°C |
2575°F |
Mechanical Properties
The mechanical properties of Inconel 751™ are outlined in the following table.
|
Properties |
Metric |
Imperial |
|
Tensile Strength (precipitation hardened, value at room temperature) |
1275 MPa |
184900 psi |
|
Yield strength (at strain 200%, precipitation hardened, value at room temperature) |
875 MPa |
127000 psi |
|
Elongation at break (precipitation hardened) |
25% |
25% |
Thermal Properties
The thermal properties of Inconel 751™ are displayed in the following table.
|
Properties |
Metric |
Imperial |
|
Thermal expansion co-efficient (at 20-100°C/68-212°F) |
12.6 µm/m°C |
7 µin/in°F |
|
Thermal conductivity |
12 W/mK |
83.3 BTU in/hr.ft².°F |
Other Designations
Other designation equivalent to Inconel 751™ is DIN 2.4694.
Fabrication and Heat Treatment
Machinability
Inconel 751™ can be machined using conventional machining methods which are usually used for iron-based alloys. Commercial coolants are used for performing machining operations. High-speed operations such as grinding, milling, or turning, are performed using water-based coolants.
Forming
Inconel 751™ is formed using all conventional techniques.
Welding
Inconel 751™ is welded using shielded metal-arc welding, gas-tungsten arc welding, gas metal-arc welding, and submerged-arc welding methods.
Forging
Inconel 751™ is forged at 1038 to 1205°C (1900 to 2200°F).
Hot Working
Inconel 751 ™ is hot worked at 983 to 1205°C (1800 to 2200°F).
Cold Working
Inconel 751 ™ can be cold worked using standard tooling.
Annealing
Inconel 751™ is annealed at 1177°C (2150°F) for 1 hour followed by cooling.
Applications
Inconel 751™ is used in exhaust valves of heavy duty diesel engines.