High-temperature resistance metals are designed for applications where temperature is sufficient to melt regular-grade materials.
Almost all metals that are able to withstand temperatures of 500℃ and above are high-temperature alloys. These materials are a combination of metals and additional elements that are selected for specific property traits, which in this case is heat resistance. High-temperature alloys are frequently used in the aerospace industry, military applications, and electronics applications, as well as applications in other extreme heat environments.
High-temperature resistance metals are also known as refractory metals. These metals are much harder at room temperature and typically have a higher melting point. The term ‘refractory’ is used in specific fields, most notably in materials science.
Metals are engineered for their service environment of which heat is just one of many factors. Heat in an oxygen atmosphere is far different than heat in a hydrogen atmosphere. So, heat resistance parameters depend strongly on the environment in which the materials are used.
Many jet engine parts are made from a nickel-based alloy with tantalum, titanium and niobium. These alloys are added to enhance the strength and resistance in the type of hot oxygen-rich atmosphere that exists inside a jet engine. The surface of the metal builds up a protective oxide layer with these alloying elements that shields the metal at high temperatures. In refineries and nuclear reactors, zirconium-based alloys are better suited for the types of high-temperature environments that these megaliths create.
There are several suitable metals for high-temperature applications, but the best choice for each is dependent on several factors. Below are some of the best available heat-resistant metals and alloys — and the characteristics that make them desirable.
Non-refractory heat-resistant alloys
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While both nickel and stainless steel have relatively high melting points, they are best used as alloys with other metals mentioned in the next two sections. Below are some characteristics that make nickel and steel alloys sought-after materials for high-temperature applications.
Nickel alloys are oxidation and corrosion-resistant materials well-suited for extreme environments. They provide excellent mechanical strength and have good surface stability. Nickel alloys are commonly used in the aviation and aerospace industries.
Stainless steel alloys resist corrosion, maintain their strength at high temperatures, and are easy to maintain. These alloys are usually made by combining steel with chromium, nickel and molybdenum, and are produced as sheets with varying thickness.
Heat-resistant stainless steel is used in a wide range of applications, including:
- Automotive industry
- Aerospace industry
- Ceramic industry
- Glass industry
- Chemical and petrochemical industry
- Hardening plants
- Incineration plants
- Steam boilers
Low-melting-point refractory metals
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Titanium has the highest strength-to-weight ratio of any metal. Its high corrosion resistance, fatigue resistance, and ability to withstand high temperatures make it an ideal substance for the aerospace, military, and marine industries. Titanium is used for landing gear, hydraulic systems, and naval ship construction.
Chromium is a metal that is most commonly used in stainless steels and titanium alloys as an alloying agent. This hard and brittle metal owes its wide use, especially that for plating purposes, to its high corrosion resistance, which is a result of its thin surface oxide layer.
Chromium and molybdenum (discussed below) are often alloyed with steel for use in a number of applications and industries. These alloys are normally grouped together, with names such as chrome, croalloy, chromalloy, moly or CrMo. Chromium is commonly used in the construction, energy, and automotive industries.
Lesser-known pure metals
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Niobium, also known as Columbium, is less dense than all the other metals on this list. It is a ductile metal primarily used in steel alloys, as it significantly improves the heat-resistant properties of steel. It is commonly alloyed with tungsten (mentioned below) for heat-intensive applications such as aircraft turbines, nuclear reactors, and jet engines. However, based on its lightweight, dependable nature, it is used mostly in medical and surgical applications.
Molybdenum is a plentiful, cost-effective metal known for its strength and stability in high-heat applications. Softer and more ductile than tungsten, it is often alloyed with other compounds, most commonly steel, to improve corrosion resistance and strength at high temperatures. Molybdenum is most commonly used in the military industry and specialty machine shops.
Like niobium, tantalum is a heat-tolerant refractory metal with excellent corrosion resistance. Often alloyed with other metals, tantalum is used to make superalloys, which are materials used in extreme environments, such as chemical processing plants, jet engines, and nuclear reactors. Its oxidation properties also make it an excellent choice for many heat-sensitive electronic applications, including electrolytic capacitors and high-power resistors.
Tungsten has the highest melting point of all metals and, at temperatures greater than 1650°C, the highest tensile strength. Its thermal expansion rate is similar to that of borosilicate glass and silicon. Its hardness and high-density make it ideal for military applications, rocket nozzles, and turbine blades — and it is also used in electron emitters, heater coils, cathode ray tubes, and a variety of high-heat applications. Along with the highest melting point, tungsten also has the lowest coefficient of thermal expansion, lowest vapour pressure, and highest tensile strength of all metals in pure form.
Tungsten alone is not a great material as it is more fragile than glass, even with its extremely high melting point. It needs to be alloyed with other materials to take advantage of its inherent heat-resistant properties.
Making use of high-temperature-resistant metals
There are various applications in engineering and product design for these types of metals.
In the cement industry, revolving cylindrical furnaces require high-temperature-resistant materials — and industrial furnace construction requires these materials for the heat treatment of coils and wires. They are also crucial for steel glow systems and exhaust systems in the automotive industry.
These metals are ubiquitous and important — from the food industry to the pulp industry and countless others. For more information on these and other materials that are imperative for modern manufacturing, take a look at the thousands of options available on Matmatch.
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