Select high-temperature alloys based on their composition, characteristics, and applications

2024-09-11

High temperature alloys broadly refer to those materials which provide strength, environmental resistance and stability within the 500°F (260°C) to 2200°F (1205°C) temperature range. They have been used generally in the presence of combustion from heat sources such as turbine engines, reciprocating engines, power plants, furnaces and pollution control equipment.

If your need custom alloy components that can function in high temperatures, then you should know that there are specific metals that suit your needs particularly well.

If your business works with alloys in hot environments, choosing the right alloys for a high-temperature service can be confusing. Experts from Lork Group help you solve these confusions. After all, there’s no such thing as uniformity when it comes to working in extreme temperatures.

Every alloy has properties that make it react differently to other alloys when subjected to prolonged periods of heat.

Therefore, it is vital that you check the technical data, which describes the properties of the alloy, before deciding if it is ‘best fit’ for the specific operating environment.

The alloy you require will depend on the function it will serve. Therefore, it is critical that designers understand and document expected operating conditions.

In the following sections, we will go over Nickel and Stainless steel of the high-temperature metals, outlining their components, properties, and uses. Armed with this information, you will be in a better position to decide which one of these high temperature alloys is the right solution for you.

Stainless Steel

Stainless steel is an alloy that is composed of three different metals: iron, chromium, and nickel. A special heat-treating process is used to combine these three elements to form stainless steel.

This process can be summarized as follows:

Melting
Tuning/Stirring
Forming
Heat Treating
Cutting/Shaping/Finishing

Of its many properties, two of stainless steel’s most popular engineering features are its corrosion resistance and eco-friendliness. Stainless steel is often referred to as “green material” since it can be recycled an infinite number of times. As for its heat-resistant properties, stainless steel’s melting point falls anywhere between 1400 to 1530 °C (2550 to 2790 °F).

The reason the melting point is an average and not an exact number is due to the variable amounts of mixed elements that are combined to form different stainless steel grades.

The three elements that stainless steel is made from all have different melting points:

iron (1535 °C—2795°F)

chromium (1890 °C—3434 °F)

nickel (1453 °C—2647 °F)

Depending on how much of either of the three elements are used will affect its final melting point to a lesser or higher degree. However, the melting points will almost always fall between the averages that were previously mentioned. Stainless steel has widespread use in many applications due to its desirable manufacturing and engineering properties.

These include:

Corrosion Resistance

High-Temperature Resistance

Low-Temperature Resistance

High Tensile Strength

Durability (under high heat and harsh conditions)

Easy Fabrication & Formability

Low Maintenance

Attractive Appearance

Eco-Friendly (unlimited recyclability)

It does not need to be painted, treated, or coated once it is put into use, and its low-maintenance requirements are among its most sought-after qualities.

As a result, stainless steel is very popular, especially for the following applications:

Buildings (exterior cladding, countertops, handrails, backsplashes)
Bridges
Kitchen Knives
Refrigerators & Freezers (finish material)
Dishwashers (finish material)
Food Storage Units
Oil, Gas, & Chemical Components (tanks, pipes, pumps, valves)
Sewage Plants
Desalination Plants
Ship Propellers
Power Components (nuclear, geothermal, solar, hydro, wind)
Turbines (steam, gas)

Stainless steel’s high melting point and high tensile strength increase a product’s stress resistance, structural load, and life cycle.

Nickel

Like many of the other heat-resistant metals on this list, nickel is a silvery-white transition metal known for its high melting point (1455°C—2651°F) and corrosion resistance.

Nickel’s high corrosion resistance makes it useful for plating and coating other metals, as well as for the creation of alloys like stainless steel.

Nickel’s high melting point is a direct result of the attraction of its positive and negative ions (protons and electrons) which form a strong bond that can hold together even under tremendous pressure and heat.

Since nickel is a naturally-occurring metal that is found abundantly in earth deposits, it is not created through any process but extracted from rock formations (ultramafic and igneous mafic) located mostly in tropical climates.

Nickel alloys, on the other hand, are formed by combining nickel with other metals like aluminum, titanium, iron, copper, and chromium through a simple heat treatment process.

These alloys are then used to manufacture a variety of products in different industries.

There are approximately 3,000 nickel-based alloys in use today.

The common properties exhibited by all variations of nickel alloys include:

Strength
Toughness
Soft Magnetic Properties
Corrosion Resistance
Heat Resistance
Easy Fabrication (good weldability)

As was mentioned earlier, nickel-based alloys are used for many applications within different industries and while the list is quite extensive.

It can be condensed down to the following:

Electric Ovens
Toasters
Transformers
Inductors
Armor Plating
Boat Propellor Shafts
Turbine Blades
Steel Plating
Stainless Steel Alloys
Corrosion-Resistant Alloys
Batteries (nickel cadmium, nickel-metal hydride)
Coins (US five-cent piece)
Magnetic Amplifiers
Magnetic Shields
Storage Devices
Spark Plugs
Automobile Electrodes

Nickel is highly resistant to oxidation even in extremely hot temperatures and can prevent electrical corrosion.

As a result, it is a great choice for the creation of heat and corrosion-resistant alloys that are needed to fortify applications working in corrosive and hot environments.

Quite often the operating temperature is the first, and in some cases, the only data point that many people look at when making their choice of alloy. This is the wrong thing to do.

Heat resisting alloys should NOT be selected on the basis of maximum operating temperature alone, there are many other things to take into consideration. These include:

The mechanical properties of the alloy at a specific temperature.
The alloy’s resistance to oxidation.
The alloy’s resistance to hot corrosion.
The metallurgical stability of the material.

Lork Group is an supplier of industrial metals to the global aerospace, oil and gas, power generation, petrochemical, bio-medical, pharmaceutical, and other high tech manufacturing industries. Products of premium metal products including Inconel alloys,Incoloy alloys,Monel alloys,Haynes alloys,Hastelloy alloy,stainless steelandother superalloy. We certify to most ASME, ASTM, AMS, and military specifications as well as most international standards certification.

The most common alloy material used for surgical instruments

Marine engineering Hastelloy C22 Chlorination system