As metals increase in temperature, their strength and oxidation resistance tend to diminish. To perform effectively at high temperatures, metals must be able to retain their strength, creep and corrosion resistance, and other physical and mechanical properties, but only specific types of metal can achieve this. Many of these high-temp specialty metals, like Hastelloy and Inconel, are proprietary superalloys of nickel and other elements.
Fortunately, when selecting a metal or alloy for an extremely high-temperature application, you have a variety of options. Here’s a breakdown of some of the most useful high-temp specialty metals and alloys for extreme temperature applications.
Mid- to High-Temp Specialty Metals
Which high-temp specialty metal you choose depends on how hot the application is. Some low-carbon stainless steels, such as 304L, can be used at temperatures up to approximately 1,400°F. However, the strength and oxidation resistance of steel rapidly begin to decline at high temperatures.
Invar is an iron-nickel alloy known for its ability to resist thermal expansion over a range of temperatures. Invar 36, for example, maintains nearly constant dimensions up to about 600°F. While it can withstand high temperatures, it begins to lose its useful properties past that range, so it is not a true high-temp specialty metal.
Monel is another specialty alloy with decent temperature resistance. Monel 400 can be used at temperatures up to 900°F, making it adequate for many moderately high-temperature applications, especially those with harsh conditions requiring high corrosion resistance like refinery components.
What about titanium? Titanium and its alloys are also great mid- to high-temp specialty metals with a maximum service temperature of around 900°F. Titanium alloys are commonly used in aircraft, missiles, and rockets where heat resistance is vital.
True High-Temp Specialty Metals
Invar, Monel, titanium, and even stainless steel can be great options for many moderately high-temperature applications, but when temperature requirements are higher, true high-temp specialty metals are needed. Fortunately, there are several options for metals and alloys with extremely high service temperatures.
Below we’ll look at four of the most heat-resistant metals and alloys in the world—Inconel, Hastelloy, molybdenum, and tungsten.
Inconel is a registered trademark of Special Metals Corporation for a series of nickel-based high-temp specialty metals. Some Inconel alloys can maintain their strength at temperatures up to 2,000°F.
Inconel has excellent corrosion resistance, oxidation resistance, and mechanical properties across extremely low and high temperatures. These properties make Inconel useful for many components in the energy and chemical processing industries.
Hastelloy is a registered trademark of Haynes International for a series of heat-resistant superalloys with excellent corrosion and oxidation resistance at high temperatures. The addition of molybdenum as an alloying element improves its high-temperature performance and gives it excellent formability and weldability. Some Hastelloy alloys have maximum service temperatures as great as 2,200°F.
Molybdenum is a plentiful, cost-effective metal with exceptional strength and stability at extremely high temperatures. It is most commonly used as an alloying element in steel, cast iron, and superalloys to improve their strength, electrical conductivity, and resistance to corrosion, wear, and heat. Molybdenum is often used in the military and defense industry.
Tungsten is an incredibly hard, dense, heat-resistant metallic element. Its melting point of 6,200°F is the highest of any free element. Like molybdenum, tungsten is often used as an alloying element to make extremely hard, high-temp specialty metals, such as high-speed steel and Hastelloy. Tungsten’s low coefficient of thermal expansion and high melting point make it ideal for applications like electric light filaments, furnace components, and rocket nozzles.
Tungsten can safely withstand operating temperatures of 3,500-4,500°F—hotter than any other metal. Its astoundingly high melting point and service temperature range often make it the only feasible choice for application temperatures in this range.
Properties of High-Temp Specialty Metals
The table below summarizes the high-temp specialty metals discussed above, their maximum recommended service temperatures, and their melting points.
|Maximum Service Temperature (°F)
|Melting Point (°F)
High-Temp Specialty Metals at Discounted Prices
For more than two decades, Industrial Metal Service has been supplying high-temp specialty metals and alloys to hundreds of customers in the San Jose area and beyond. We also provide precision cut-to-size sawing services, delivery throughout the San Francisco Bay Area, and scheduled metal recycling, making us a one-stop provider for all your industrial metal needs.