Working on projects in a high temperature environment? Choosing metal alloys with a high melting point is an absolute must.
However, extreme temperature conditions vary from business to business, making purchasing the right product a little confusing. A heat resistant alloy that works in one context can fail to withstand extreme temperatures (of a different degree) in another.
Our goal here is to break down the most heat resistant metals on the market ─ their components, properties ─ and highlight a few important considerations before you commit to your purchase.
What makes a metal alloy heat-resistant?
Heat resistance applications typically require consistent performance at temperatures over 1200°F (649°C). Alloys with high performance levels of oxidation resistance, creep strength, stress rupture life, and tensile strength contribute to heat resistance properties.
Most heat-resistant alloys include some or all of the following elements:
In addition to alloying, heat-resistant steel is strengthened by heat treatment, precipitation (age) hardening, and solid solution hardening.
Heat resistant alloys can be subdivided into three different levels, based upon their operating environment. Those that can be subjected to:
- Small amounts of heat stress (seconds to minutes)
- Moderate levels of heat stress (hours or hundreds of hours)
- Long periods of heat stress (thousands of hours)
Trade-offs to heat resistance
Depending upon the metal alloy, additional performance factors may be sacrificed to gain heat resistance characteristics, including:
- Thermal Expansion
- Creep (Metal stretching)
- Rupture strength
- Thermal fatigue
- Oxidation and corrosion
- Vacuum performance/exposure to other atmospheres
Metals with heat resistant properties
1) Titanium (Ti) – Often described as a ‘sponge’ on account of the porous holes within its structure and on the surface from the formation process. Titanium alloys have high corrosion resistance, are extremely tough, can withstand high temperatures, and have a high tensile strength-to-weight ratio. They are easily weldable, fabricated and are highly effective in challenging industrial applications.
2) Tungsten (W)– A steel-grey or silver-white refractory metal. Tungsten provides hardness, resistance to high heat and can be used as a base metal for an alloy or as a supporting element.
3) Stainless Steel (Alloy) – A family of alloys known for their resistance to corrosion and high temperatures, stainless steel is an iron-based alloy that contains 10.5% or more chromium and other elements such as nickel and molybdenum. Steel alloys can be highly heat-resistant. The aerospace, automotive and construction industries use this material to create specific parts such as pressure vessels or boilers.
4) Niobium (Nb) – Formerly called Columbium (Cb), niobium is used in steel alloys and has hardness characteristics similar to titanium (and ductility similar to iron). It is commonly alloyed with tungsten for superior resistance to heat. This metal is commonly found in surgical equipment as well as jet engines and aircraft turbines.
5) Molybdenum (Mo) – Molybdenum is frequently used in steel alloys including stainless steel. It provides enhanced strength, durability and resistance to corrosion, wear and high temperatures. It’s ductility and softness make it ideal for specialty machinery and military applications.
6) Nickel (Ni) (Alloy) – Nickel has superior strength, is malleable and ductile, and has exceptional resistance to oxidation and corrosion. Nickel is frequently used in stainless steel alloys for added strength. Nickel alloys are some of the most heat-resistant metals.
7) Tantalum (Ta) – Tantalum has a high density, melting point and acid resistance. It has an oxidized film on its surface that provides corrosion resistance. This material is often combined with other metals to produce superalloys.
Other considerations for high temperature alloys
The previously listed trade-offs demonstrate many of the important factors for consideration, including physical properties such as thermal expansion and thermal fatigue as well as post-metal processing considerations such as weldability. Cost and availability may also be factor.
It is important to verify the technical data of an alloy before you decide to use in any high temperature environment. But, do not select your metals solely on the maximum operating temperature. Factor in:
- Oxidation resistance
- Hot corrosion resistance
- The material’s metallurgical stability
- Mechanical properties at different temperatures
Some high temperature alloys carry interesting material properties. For example, titanium carbide has the highest melting point of all metals at 3100°C. Stainless steel does not require painting.
Applications & services that require high temperature resistance
Heat-resistant metals are found in many different industries including:
- Machine Shops
Many essential products are produced including boilers, electron emitters, electronics, jet engines, nuclear reactors, turbine blades and even nuclear reactors.
If you’re looking for heat resistant metals for your next project, browse our selection online or contact your local Metal Supermarkets for an accurate quote that fits your needs. Our team of metal experts are standing by to help.