Invar, also known as FeNi36, is an important alloy used in aerospace applications due to its low thermal expansion and high strength. Developed by Swiss physicist Charles Édouard Guillaume in 1896, this alloy has since become a pivotal part of the aerospace industry.

This article will explore the properties of Invar that make it a suitable material for aircraft components, as well as outline considerations for designing with it. With this information, aerospace engineers will be better equipped to use Invar for their projects.

Invar’s ability to maintain size and shape under extreme temperatures makes it an ideal choice for aircraft components exposed to large temperature variations. It can also withstand high mechanical loads and is resistant to corrosion in many environments. The combination of these properties makes Invar a valuable resource to the aerospace industry.

However, there are certain design considerations that must be taken into account when working with this alloy in order to ensure optimal performance and safety.

Overview Of Invar

Overview Of Invar

Invar is an alloy of iron and nickel with a chemical composition of 36% nickel and 64% iron.

It is well-known for its unique combination of properties, including low thermal expansion, high strength, and good corrosion resistance.

Invar is used in the aerospace industry to manufacture components that need to withstand extreme temperatures, such as turbine blades in aircraft engines and rocket nozzles.

The machining of Invar can be challenging due to its work hardening properties.

The material’s tendency to work harden during machining processes leads to a decrease in tool life and an increase in cutting forces.

To counter this, special cutting tools are usually employed, such as inserts with multiple edges or coated carbide tools.

Additionally, higher cutting speeds are often used when machining Invar compared to other similar materials.

Benefits Of Invar For Aerospace Applications

Invar is a nickel-iron alloy that can be used in a variety of aerospace applications. It has become increasingly popular due to its unique physical and chemical properties. Invar exhibits low thermal expansion, stability under temperature fluctuations, and excellent corrosion resistance, making it an ideal choice for the production of components used in aerospace engineering.

The advantages of using Invar in aerospace applications include:

  • Cost Savings: Using Invar in production can result in significant cost savings as it eliminates the need for expensive alloys such as stainless steel or titanium.
  • Aerospace Standards: Invar meets most industry standards for aerospace products, ensuring that parts produced with this material will meet quality requirements.
  • Durability: The superior strength and durability of Invar make it suitable for use in aircraft engines and other high stress components. This helps reduce maintenance costs and prolong the life span of the part.

Using Invar in the production of aerospace components offers several distinct benefits which make it an attractive option for companies looking to cut costs while maintaining quality standards. Its versatile nature and ability to perform consistently under extreme conditions makes it an ideal choice for many aerospace applications.

Mechanical Properties Of Invar

Invar is a type of steel alloy that is most often used in aerospace applications due to its unique mechanical properties.

It has an impressive coefficient of thermal expansion (CTE) of 0.5 μm/m°C over a wide range of temperatures, making it ideal for use in aircraft and spacecraft components.

In addition, Invar offers excellent tensile strength, hardness and wear resistance when properly heat treated.

The heat treatment process for Invar involves preheating the material before subjecting it to an annealing process.

This preheating step helps to reduce internal stresses that have built up in the material during manufacturing or machining processes.

During the annealing process, the material is heated above its transformation temperature and then cooled slowly at a controlled rate.

The result is an alloy with improved ductility and toughness without sacrificing any of its other desirable mechanical properties.

Thermal Expansion Properties Of Invar

Invar, an alloy of iron and nickel, is widely used in aerospace applications due to its low coefficient of thermal expansion. This property makes it suitable for precision machining and heat treating. Its ability to maintain a constant size over a wide range of temperatures means that components made from Invar are ideal for aspects of the aerospace industry such as rocket engines and satellites.

The low thermal expansion properties of Invar also make it attractive for use in other industries such as electronics and clock making. The material has been developed to have an extremely tight tolerance when machined with precision tools and subjected to proper heat treating techniques. This makes it possible to create parts with exact dimensional tolerances which can be used in a variety of high-precision applications.

Invar is a highly versatile material with many useful features that make it the preferred material for aerospace applications. It can be easily machined, produces components with precise tolerances, and offers excellent thermal stability over a wide temperature range.

These characteristics make Invar an ideal material choice for aerospace engineering projects where precision and reliability are key considerations.

Corrosion Resistance Of Invar

Invar is an alloy that is highly valued for its thermal expansion properties, but it also has excellent corrosion resistance.

Invar’s ability to resist corrosion is a result of its low carbon content and protective layer of oxides that are formed on its surface. This layer helps to protect the underlying material from further corrosion.

In addition, invar can be electroplated with other materials such as zinc, nickel or chromium to provide additional galvanic protection. Invar’s corrosion resistance also comes from its composition, which is primarily composed of iron and nickel.

The majority of invar alloys contain 36 percent nickel, resulting in a low carbon content that reduces the risk of rust formation. Additionally, invar does not contain elements such as copper or bismuth that are commonly found in other alloys and can cause galvanic corrosion when exposed to water or moisture.

Invar’s excellent corrosion resistance makes it an ideal choice for aerospace applications where parts must withstand harsh environments while maintaining their structural integrity over time. Its combination of low carbon content and electroplating make it one of the most reliable alloys available today for protecting against rust and other corrosive agents.

These features make it a popular choice for components such as aircraft landing gear and engine parts due to their durability over time in extreme conditions.

Design Considerations For Invar

Design Considerations For Invar

Invar is a popularly used steel alloy in the aerospace industry due to its low coefficient of thermal expansion. It is an ideal material for applications that require precision, stability, and durability.

The unique properties of Invar make it suitable for a variety of applications, including rotor blades and wing structures. When designing components with Invar, engineers must consider numerous factors such as welding techniques, fatigue strength, corrosion resistance, and weight optimization.

To ensure that the component can withstand high temperatures, robust welding techniques must be employed. Additionally, fatigue strength must be taken into account to prevent premature failure due to cyclical loading and high temperature exposure over time. Corrosion resistance should also be taken into consideration during the design process as a result of Invar’s increased susceptibility to corrosion in moist environments.

Lastly, weight optimization should also be factored into the design process to reduce unnecessary mass while ensuring structural integrity. It is important for engineers to consider these design considerations when working with Invar for aerospace applications in order to ensure that components meet all safety criteria and perform optimally under extreme conditions.

Optimizing these parameters will help aerospace engineers create durable and efficient components without compromising on quality or performance.

Manufacturing Invar Components

Manufacturing Invar Components

When it comes to manufacturing Invar components, there is a wealth of machining processes and techniques available. The choice of which one to use will depend on the complexity of the part being manufactured, as well as its intended purpose.

When it comes to machining Invar, there are several options ranging from traditional to robotic methods. Traditional machining processes such as drilling, turning, milling, and grinding are all suitable for Invar components. For more complex parts, however, robotic milling may provide an even greater level of accuracy and precision. This method is especially useful if the part needs to be made within very tight tolerances or has intricate features that would be impossible to machine by hand. Additionally, robotic milling offers faster production times than manual machining processes.

No matter which method is used for manufacturing Invar components, the end result should meet the required standards for aerospace applications.

Joining Invar With Adhesives

Invar is an important alloy for aerospace applications due to its low coefficient of thermal expansion. This is especially beneficial when joining two parts, as it helps reduce the chances of misalignment resulting from thermal changes.

Invar can be joined using various welding techniques or mechanical fasteners, but it can also be joined using adhesive bonding methods. Adhesive bonding is a popular joining method for Invar components in aerospace applications, as it offers advantages such as high flexibility and strength.

Adhesives are also easy to use and allow for quick assembly and maintenance of Invar components. Additionally, they can be used to fill gaps between components which may have been caused by manufacturing tolerances or material shrinkage during curing. It should be noted that adhesives should not be used with components that will experience temperatures higher than the specified temperature range of the adhesive.

Adhesive bonding opens up many possibilities for Invar components in aerospace applications, allowing for easy assembly and maintenance while ensuring strong and reliable connections between parts. With proper selection and application of adhesives, engineers can create structures that are able to withstand extreme conditions such as those experienced in aerospace applications.

Typical Aerospace Applications Of Invar

Typical Aerospace Applications Of Invar

Invar, an alloy of iron and nickel with a low coefficient of thermal expansion, has become indispensable in aerospace applications. It is widely used to manufacture components such as engine blades and landing gear due to its strong resistance to corrosion and fatigue.

According to recent studies, the global market size of Invar for aerospace applications was estimated at nearly $3 billion in 2019 and is projected to increase by 8.6% every year until 2027.

Invar can be easily fabricated into complex shapes using techniques such as casting, forging, welding, machining, and powder metallurgy. The cost comparison between Invar and other materials can vary significantly depending on the production process.

For example, Invar is more economical than titanium when it is machined into complex shapes but more expensive than aluminum when produced through casting processes. Its unique properties make it particularly suitable for use in critical aircraft components where weight savings are desired without sacrificing strength or durability.

Invar Vs. Other Alloys In Aerospace Applications

Invar, an iron-nickel alloy with a low coefficient of thermal expansion, is a highly sought after material for aerospace applications due to its outstanding properties.

It is commonly used in aircraft components that require precise dimensional stability over wide temperature ranges.

Invar offers several advantages compared to other alloys when used in aerospace applications:

  • Weight savings: Invar is much lighter than other metals, such as steel and aluminum, which makes it ideal for use in aircraft components where weight is a major consideration.
  • Thermal stability: Due to its low coefficient of thermal expansion, Invar maintains its strength and shape even at high temperatures. This makes it an ideal choice for parts that are exposed to extreme temperatures during flight.
  • Fatigue strength: Invar has excellent fatigue strength, meaning it can endure repeated cyclic loading without cracking or failing. This makes it ideal for use in components that experience high levels of stress during operation.

Overall, Invar is a superior alloy for aerospace applications due to its light weight, thermal stability, and fatigue strength.

Its low thermal expansion rate also ensures precise dimensional control and accuracy over wide temperature ranges while remaining strong and durable under the most demanding conditions.


Invar is an alloy that offers a variety of benefits to aerospace applications. Its low thermal expansion, high mechanical strength, and corrosion resistance make it an ideal choice for manufacturing components that require precise dimensional tolerances in extreme temperatures and environments.

The unique properties of Invar have seen it become increasingly popular with aircraft manufacturers, who rely on its precision and reliability. For example, the new Boeing 787 Dreamliner has over 2 million parts made from Invar alloys, demonstrating the trust placed in this remarkable material.

Invar is now seen as a vital component of the modern aerospace industry and looks set to remain a key part of the sector for years to come.