Inconel 718 Applications in Aerospace

Description of Inconel 718

Inconel 718 is a high-temperature nickel-based alloy that offers exceptional strength, corrosion resistance, and thermal stability. It contains nickel, chromium, iron, and other elements that provide it with unique properties such as high-temperature strength, good weldability, and outstanding resistance to oxidation and carburization. JN Alloy is a leading supplier of Inconel 718 plates, pipes,  fittings,  bars and  flanges. This article will provide a detailed analysis of Inconel 718 application in aerospace, covering its chemical composition, mechanical properties, applications, standards, and comparison with other  alloys.

Inconel 718 comprises of considerable magnitudes of iron that makes it cheap while providing precipitation hardening properties. The basic purpose of development of Inconel 718 was to overcome the problem of poor welding properties of this class of metals. The presence of special metals provides excellent corrosion resistance up to 1000oC. Nickel prevents chloride ion stress corrosion cracking and secures from corrosion in various organicand inorganic oxidizing media, in the variety of acidic and alkaline media. Chromium prevents corrosion in oxidizing and sulfidizing conditions while molybdenum enhances resistance to pitting.

Inconel 718 (UNS N07718) is the most widely used superalloy, accounting for approximately one-third of all superalloy production. Inconel 718 has excellent strength, ductility, and toughness throughout the range -423°F to 1400°F. A major attribute of Inconel 718 is its processing versatility. It can be fabricated over a wide range of temperatures, forging reductions, and strain rates to produce microstructures and associated properties tailored for specific requirements. From cryogenic temperatures to 1400°F, Inconel 718 remains stable, demonstrating exceptional tensile and impact strength even when exposed to harsh conditions. With its unique combination of properties, Inconel 718 is a great choice for numerous applications, from petrochemical to aerospace. It has good weldability and high resistance to oxidation and stress corrosion cracking.

Alloy 718 (Inconel 718, UNS N07718, 2.4688) was originally developed for potential application in supercritical (very high temperature) steam power plants. The alloy composition is predominantly a nickel-chrome base meaning it is resistant to oxidation at elevated temperatures. However, the addition of Nb, Ti, Al and Ni form a series of precipitates during the controlled solution annealing and ageing process steps, resulting in a significant increase in strength and hardness compared with alternative nickel alloys. In addition, these precipitates provide excellent temperature stability and creep resistance, which is why it became more widely used in aerospace applications.

Analysis from the mechanical properties

Traditional manufacturing methods are challenging when applied to Inconel 718 and one often ends up sacrificing the excellent material properties (high temperature corrosion and creep resistance) to obtain the desired shapes. Machining, forging and welding also require the material being preliminary annealed to induce ductility and better deformability. The following features of Inconel 718 make it suitable for aerospace applications:

Unmatched Strength: Inconel 718 boasts remarkable tensile, fatigue, and creep-rupture strengths, making it a preferred choice for applications that require exceptional load-bearing capabilities.

Corrosion Resistance: Inconel 718's resistance to both aqueous and high-temperature corrosion sets it apart in challenging environments such as aerospace, marine, and chemical processing industries.

Temperature Tolerance: With a melting point of around 2,500°F (1,370°C), Inconel 718 retains its mechanical properties at elevated temperatures, making it ideal for high-temperature applications.

Weldability: Inconel 718 exhibits excellent weldability, allowing for the fabrication of complex structures and components without compromising its mechanical integrity.

Fatigue Resistance: Inconel 718's fatigue strength is exceptional, contributing to its suitability for applications subjected to cyclic loading, such as jet engine components and gas turbine discs.

Other materials that can be used in aerospace

With the many advantages associated with Nickel based alloys, it is evident that they are indispensable to the aerospace industry. Without the use of these versatile metals, aircrafts would have trouble finding a replacement alloy to provide them with the same features that are essential for the high level of efficiency and reliability that are enjoyed today. The following alloys are also suitable for aerospace applications: Alloy X, Alloy B2, Alloy 321, Alloy 600, Alloy 601, Alloy 625, Alloy 718, Alloy 400, Alloy K500, Aolly 200, Aolly 201 and so on. JN Alloy can provide you with products made of these materials. If you have any needs, please contact us.