AMS 5663 Inconel 718, also known as Alloy 718 or UNS N07718, is a high-strength, corrosion-resistant nickel-chromium alloy, ideal for many industries due to its unique properties. This article will explore the characteristics, applications, and history of Inconel 718, providing a comprehensive understanding of this versatile alloy.
What is Inconel 718?
Inconel 718 is a nickel-chromium alloy that contains significant amounts of iron, columbium, and molybdenum, along with lesser amounts of aluminum and titanium. It is characterized by high strength, good ductility, oxidation resistance at high temperatures, and excellent cryogenic properties.
Key Properties and Characteristics
Inconel 718 is known for its unique set of properties, including:
- High Strength: It maintains its strength at high temperatures and has excellent cryogenic properties, making it ideal for applications in extreme conditions.
- Corrosion Resistance: The nickel-chromium base provides exceptional resistance to a wide range of corrosive environments.
- Excellent Weldability: Inconel 718 can be readily worked and age-hardened, allowing it to be welded in fully aged conditions.
Chemical Composition
Inconel 718’s chemical composition includes a balance of multiple elements:
| Chemical Element | Minimum % | Maximum % |
| Nickel (Ni) | 50 | 55 |
| Chromium (Cr) | 17 | 21 |
| Iron (Fe) | – | Bal |
| Molybdenum (Mo) | 2.8 | 3.3 |
| Niobium (Nb+Ta) | 4.75 | 5.5 |
| Titanium (Ti) | 0.65 | 1.15 |
| Aluminum (Al) | 0.2 | 0.8 |
Mechanical Properties
Inconel 718 exhibits excellent mechanical properties, including high tensile strength and yield strength. These properties are maintained from cryogenic to elevated temperatures.
Varieties of Inconel 718
Several conditions of Inconel 718 are available, each with unique characteristics:
- AMS 5662: This is the rawest and softest condition of Inconel 718. It can be heat treated into AMS 5663 for specific outcomes.
- AMS 5663: This is achieved by heat treating AMS 5662. Certain outcomes such as optimum impact properties or optimum tensile and creep-rupture properties can be achieved through this process.
- AMS 5664: This has a more complicated forming process and offers higher tensile and yield strength, along with specific grain size restrictions.
- NACE MR-01-75: This version is produced in accordance with API (American Petroleum Institute) standards and offers a different range of characteristics.
Applications of Inconel 718
Inconel 718 is used in various industries because of its unique properties:
- Aerospace: It provides the vital strength aircrafts require, withstanding the intense heat of the afterburners and the freezing temperatures experienced at high altitude.
- Chemical processing: Its high strength and corrosion resistance make it suitable for various applications in the chemical processing industry.
- Oil and Gas: Inconel 718 is the preferred material for many oil, offshore, and OEM applications.
Inconel 718 in the Aerospace Industry
Inconel 718 plays a vital role in the aerospace industry. It is used in the construction of various components such as:
- Cryogenic storage tanks
- Downhole shafting
- Gas turbine components
- High strength bolting
- Jet engines
- Nuclear fuel element spacers
- Pump parts
- Pump shafts
- Rocket motors
- Thrust reversers
Machinability of Inconel 718
Inconel 718 can be machined using conventional production methods at satisfactory rates. The alloy work hardens rapidly, generates high heat during cutting, welds to the cutting tool surface, and offers high resistance to metal removal due to its high shear strengths.
Conclusion
Inconel 718 is a versatile alloy with a wide range of applications. Its high strength, corrosion resistance, and excellent weldability make it a choice material in various industries, from aerospace to oil and gas. Understanding its properties and uses can help businesses make informed decisions about its application.
Remember to consult with a materials expert or engineer when considering Inconel 718 for your specific application to ensure it meets your requirements and specifications.
