Inconel Sheet: A Deep Dive Into

Superalloys are the go-to alloy materials for applications with high creep, oxidation, and decay resistance level as important operational conditions. They usually comprise the group VIIA elements of the periodic table and are mostly used in jet engines and gas turbines. 

Like other superalloy products, Inconel sheets exhibit all these properties and more, and this article discusses their grades, characteristics, advantages, limitations, and applications. Read on! 

What Is Inconel Alloy?

Inconel has remarkable strength like stainless steel, but they are not the same. Inconel is a special metal that is even more expensive than Monel—an alloy class popular for its immunity to seawater-induced corrosion. Inconel’s unique combination of metals allows it to thrive under extreme conditions, including high temperatures, pressure, and hazardous environments. 

With its maximum elongation time and elevated tensile strength, it is often used in applications where regular metals fail or deteriorate, such as aerospace, gas turbine engines, nuclear reactors, and chemical processing plants. Aside from its industrial application, Inconel is versatile and is manufactured into pipes, tubes, and Inconel sheets.

What Is Inconel Sheet?

The Inconel sheet is a product or material from Inconel Alloy. It possesses all the characteristics of the alloy, which means it has nickel and chromium as the main alloying chemical elements and has excellent mechanical properties required in industrial operations in high-temperature environments.

Inconel sheets’ immunity to heat and other deformation-inducing elements makes them ideal for use in environments where heat resistance is necessary. They also come in various thicknesses and sizes, allowing them to be used in various applications, including gas turbines, the marine sector, and oil and gas extraction. 

Inconel Sheet Specification

The Inconel sheet specification includes details on the appearance and characteristics of the alloy material. The table below covers the average Inconel sheet metal spec available in the market. However, the material spec varies between suppliers, so ensure you check in with your manufacturer for specific details. 

Inconel Sheet Properties

Inconel sheets have the same physical and mechanical properties, deformation, and high-temperature resistance as other Inconel products. However, their ASTM international specification numbers and their chemical composition differ slightly. Let’s explore more details on the key properties of Inconel sheets.

1. Inconel Sheet Chemical Composition

The first key property of the Inconel sheet material is the chemical composition, which determines the chemical elements in the metal and how they each contribute to form a high-performance alloy material. The table below gives more details about these components and their values.

Note that this is a general component of an average Inconel material because the chemical composition of Inconel alloys varies. For instance, Inconel 600 sheets have 14-17% chromium and 6.0-10.0% Iron, while Inconel 718 sheets have 17-21% chromium and 4.75-5.50% niobium.

2. Physical Properties

The physical properties of Inconel sheets include their density, lowest and highest melting point range, magnetic properties, thermal conductivity rate, electrical conductivity, etc. The table below lists the physical properties of various Inconel sheet grades. 

3. Inconel Sheet Mechanical Properties

The mechanical properties of various Inconel sheet grades and products cover their elongation at break, hardness (using Rockwell ‘B’ hardness scale), tensile strength, and other characteristics. The table shows the various values in which each grade, the measured properties, and their values.

4. Corrosion Resistance of Inconel Sheet

Corrosion occurs when a material reacts with its surrounding environment, leading to degradation and loss of properties. However, Inconel sheets have the ability to withstand the damaging effects of rust and various forms of deformation for extended periods, even in hazardous environments.   

Inconel sheet corrosion resistance is due to the high volumes of nickel and chromium, forming a protective oxide layer, preventing direct contact between the Inconel sheet and deformative substances.

Inconel sheets can withstand acidic conditions, including sulfuric acid and hydrochloric acid, as well as alkaline solutions such as sodium hydroxide. In addition, the Inconel sheet also exhibits exceptional resistance to chloride-induced stress corrosion cracking, which can occur in chloride-rich environments.

5. High-Temperature Resistance of Inconel Sheet

As with other superalloy products, the Inconel sheet’s high-temperature resistance is particularly important for applications that involve extreme heat. When exposed to elevated temperatures of up to 1400°C, many materials lose their strength and undergo deformation. However, the reverse is the case for the Inconel sheet material.

The volume of nickel and chromium in the Inconel sheet work together to form a protective layer on the sheet’s surface, known as a passivation layer. This layer acts as a barrier, preventing further oxidation and degradation of the material under extremely low below -130°F and high temperatures above 1400°C. This heat resistance makes them suitable for gas turbines, jet engines, heat exchangers, and furnace components.

6. Inconel Sheet Thickness Tolerance

They are manufactured with specific thicknesses to meet the requirements of different applications. However, it is important to consider the Inconel sheet’s thickness tolerance, which refers to the allowable deviation in thickness from the specified value. The thickness tolerance is determined during manufacturing and specified by industry standards or customer requirements. 

The tolerance level ensures that the actual thickness of the sheet falls within an acceptable range around the specified value. Inconel sheet thickness tolerance can vary depending on the manufacturing method, sheet dimensions, and the desired application. Generally, the thickness tolerance of Inconel steel ranges between -0.05mm to + 0.42mm.

7. Inconel Sheet Stress Relief

During manufacturing, Inconel sheets can undergo internal stresses that may affect their dimensional stability and mechanical properties. Stress relief treatments minimize these residual stresses and optimize the material’s performance. This is normally done by incorporating controlled heating and cooling rounds called annealing. 

The Inconel sheet stress relief treatment improves their resistance to deformation, enhances dimensional stability, and reduces the risk of cracking or distortion during subsequent processing or service. It is particularly important for applications requiring tight tolerances, high precision, and reliable performance.

Inconel Sheet Manufacturing Process

The first step in Inconel sheet manufacturing involves preparing the Inconel alloy chemical composition by melting and mixing the proportions of nickel, chromium, and other alloying elements. Then the molten alloy is controlled to achieve the desired composition and homogeneity. The next steps are;

• Casting or Hot working: The molten Inconel alloy is then solidified through a casting process or hot working. During casting, the alloy is poured into molds to create ingots or billets, which are later processed into sheets. On the flip side, if you incorporate hot working techniques, then rolling or extrusion can be used to shape the alloy into thinner slabs or billets. 
• Hot Rolling: Here, the Inconel billets or slabs are heated to high temperatures of up to 1370°C and passed through a series of rolling mills. This procedure gradually reduces the thickness and increases the length of the material, resulting in a continuous sheet.
• Cold Rolling: After heating them at high temperatures of 1370°C, the Inconel sheet undergoes cold rolling to refine its thickness, surface finish, and mechanical properties. Unlike hot rolling, cold rolling involves passing the sheet through rolling mills at room temperature.
• Annealing: To relieve any internal stresses generated during the manufacturing process and enhance the sheet’s properties, the product undergoes stress relief annealing treatment. The sheet is heated to a specific temperature and then slowly cooled down, allowing the material to reach a more stable and uniform state.

To meet customer requirements, additional finishing operations may be performed. These can include cutting, shearing, slitting, polishing, surface treatment, or coating to achieve the desired dimensions, surface quality, and functional properties of the Inconel sheet.

Inconel Sheet Grades

The categorization of Inconel sheets consists of about 18 superalloy materials and highlights their similarities and differences, even though they are from the same group. Here are eight Inconel sheet Alloy variations, their UNS numbers, and descriptions.

Applications of Inconel Sheets

Inconel sheets have found their way into various applications, showcasing their incredible versatility, strength, and resistance to seawater and chloride-induced stress. Here’s a breakdown of ten notable applications where Inconel sheets serve as solutions:

• Aerospace Industry: Inconel sheets can resist decay and hot temperatures of about 2400°F and temperatures as low as -135°F. This high heat resistance makes them ideal for high-performance aircraft engines, gas turbine components, exhaust systems, and other aerospace needs.
• Furnace Components: Inconel sheets manufacture furnace components such as radiant tubes, heat shields, and burner nozzles due to their remarkable heat resistance.
• Chemical Processing: The chemical processing sector requires high-performance alloys because of prolonged exposure to hazardous chemical elements. Inconel sheets produce chemical processing equipment like reactors, vessels, and piping systems, as they can withstand corrosion from acids, alkalis, and reactive chemicals.
• Power Generation: Inconel sheets find applications in steam turbines, nuclear reactors, and boiler systems, fighting high temperatures, steam, and chemicals, ensuring reliable power generation.
• Marine: When some metals come in contact with salt water, their physical and mechanical properties may deteriorate. Hence they are not used in settings where they’ll interact with seawater. 

Unlike these metals, Inconel sheets are commonly utilized in the marine industry for their resistance to seawater-induced corrosion, saltwater environments, and marine atmospheres, making them suitable for ship exhaust systems and offshore structures.

• Oil and Gas Sector: Crude can harm pipes and valves made from materials that cannot handle high pressure, hazardous fluids, and elevated temperatures. Engineers and industrial scientists in this sector need high-performance sheets to beat this threat, and Inconel sheets are a go-to. 

They protect against downhole equipment, drilling tools, pumps, valves, extractors, etc., from corrosive fluids, high-pressure environments, and extreme temperatures in oil refineries.

• High-Performance Racing: The pressure generated from racing automobiles can break down a low-performance alloy. However, Inconel sheets are used in exhaust systems and engine components in high-performance racing since they contribute to power, endurance, and reliability on the track.
• Medicine and Healthcare: Inconel sheets are employed in the manufacturing of surgical instruments, implants, and medical devices due to their biocompatibility, rust resistance, and strength.
• Electronics Industry: Inconel sheets are great conductors of electricity, so they are utilized in semiconductor manufacturing equipment to protect against rust-inducing gases and high-temperature processes, ensuring reliable performance in electronics production.
• Nuclear Applications: Aside from heat and deformation resistance, Inconel sheets exhibit excellent immunity to high radiation levels. Therefore, they are used in nuclear power plants for reactor systems, fuel storage, and radiation shielding.

Advantages of Inconel Sheets

From their applications, you’ll find that Inconel sheets offer gazillion advantages to various sectors, industrial workers, scientists, and engineers. Let’s dive into the following benefits of Inconel sheets.

• High-Temperature Resistance: One of the main features of Inconel sheets is their ability to resist high temperatures of about 1400°C. So, if you are working in an environment with such temperature requirements, Inconel sheets are ideal.
• Corrosion Resistance: Inconel sheets exhibit exceptional resistance to rust from oxidation, reducing agents, chloride-rich media, seawater, and various harsh chemicals, making them suitable for corrosive environments.
• Strength and Durability: Their ability to withstand extremely low and high-temperatures would be irrelevant if they cannot maintain their structural and mechanical properties in such environments. Luckily, Inconel sheets do not fall short in this aspect.
• Fatigue Resistance: Working with an Inconel sheet guarantees so many benefits. Another benefit of this product is its excellent fatigue resistance. This enables them to endure repeated stress cycles without experiencing failure or loss of performance.
• Good Weldability: You don’t have to worry about ease of fabrication with Inconel sheets. They are popular for their good weldability, allowing for easy fabrication and complex structures or assemblies.
• Versatility: Like its parent material, Inconel, these sheets are available in various grades and thicknesses, providing versatility to meet specific application requirements and design needs.
• High-Pressure Performance: Inconel sheets can withstand high-pressure environments, making them suitable for applications involving extreme pressure differentials, such as chemical processing equipment and race automobile engines.
• Cryogenic Stability: Cryogenic temperatures go as low as -130°F. Inconel sheets maintain their mechanical integrity and resist embrittlement even at cryogenic conditions, making them suitable for applications in low-temperature environments.
• Excellent Mechanical Properties: Good mechanical properties determine any alloy material’s structure, durability, profile, and strengths under prolonged exposure to certain temperatures and environments. Inconel sheets possess a unique combination of high tensile strength, yield strength, and toughness, enabling them to withstand heavy loads and impacts.
• Applications in Diverse Industries: Inconel sheets have widespread use in aerospace, chemical processing tools, pharmaceuticals, automobile racing components, power generation, marine, and more, due to their advantageous properties and ability to meet stringent industry standards.

Disadvantages of Inconel Sheets

While Inconel sheets offer numerous advantages, it is important to consider some potential disadvantages. Here are five common limitations associated with Inconel sheets:

• Cost: Inconel sheets tend to be more expensive than stainless steel and other metal alloys. The high cost is due to the complex manufacturing processes of producing Inconel alloys.
• Machinability: Inconel sheets are tough and can work harden quickly, making it challenging to achieve precise cuts and intricate shapes. Specialized machining techniques and tools are required, increasing the complexity and cost of machining operations.
• Limited Availability: Inconel sheets are less readily available than stainless steel and other metal alloys.
• Workability: Inconel sheets have lower formability than some other metals. Forming Inconel 625 sheets and other grades can be challenging, especially during bending and shaping. You’ll require specialized equipment, techniques, and skilled operators to succeed. 

Inconel sheets are unsuitable for limited budgets, but they will always be an incredible deal for applications requiring their strength, ductility, and other key properties as a strict condition.

FAQ

1. What Is Inconel Sheet Price?

The price of Inconel sheets varies depending on the alloy, thickness, dimensions, quantity, and market conditions. Inconel sheets are generally more expensive than other metal alloys, with an average price between 45$-60$ per kg. However, it is best to contact manufacturers directly for accurate pricing information.

2. Which Alloy Class Is a Good Substitute for Inconel Sheet Metal?

Any Hastelloy alloy sheet can serve as a substitute for Inconel sheet metal. Hastelloy alloys are also high-performance, offering similar high-temperature, ductility, versatility, and decay resistance properties. 

3. How Strong Is Inconel Heat Shield Sheet?

Inconel heat shield sheets have excellent strength and durability. Their strengths depend on the grade and thickness of the sheet. Still, all Inconel heat shield sheets are designed to withstand high temperatures, provide thermal insulation, and protect against radiant heat in applications such as furnaces, exhaust systems, and aerospace components.