Choosing Alloys for High Temperature Applications

The economic recovery appears to be on an upward swing as the automotive, natural gas, and petroleum industries move into high gear. Whether it is the new fuel-efficiency automotive engines or a fast moving natural gas pump, the use of fasteners that can withstand high temperature operations is critical.

Choosing fasteners fabricated with the right alloy that can operate in high temperature applications provides design challenges, as there are only certain types of fasteners that will function in high temperature situations. Fortunately, special alloys have been formed. Fasteners made out of these metals will perform well. Able to withstand temperatures up to 1000 degrees Fahrenheit (587 Celsius), these alloys are heat-treated in high temperatures and then forged together to give them this high temperature tolerance.

Some alloys that are used today in fasteners include:

  • Stainless Steel 309 & 310—these are higher in nickel and chromium content than most other alloys of similar properties. These are recommended for use in high temperature applications. Additionally, the 310 offers extra corrosion resistance for salty or other similar harsh environments.
  • Stainless Steel 630 is a precipitation-hardening stainless steel. They are hardened by a combination of low temperature aging and cold working. It is one of the most widely used precipitated-hardened steels for the fastener industry. This alloy has high tensile strength and good ductility.

However, these two are just a sampling of various alloys available. Whether special alloys, coated metals, or stainless steel, many different metals can perform in extreme temperatures, knowing which one is right for your specific application will be crucial.

Chicago Nut & Bolt recommends that you go to the best resource for help in determining the right alloy. The best information source for determining the correct alloy for your particular design need or industry application is the ASTM A193 / A193M – 12b. This is the Standard Specification for Alloy-Steel and Stainless Steel Bolting for High Temperature or High Pressure Service and Other Special Purpose Applications.

The wise thing is to consult the ASTM specifications and then to spend time talking to your materials engineer to make sure that your particular fastener application, whether it is for automotive, aerospace, energy production, or some other industry, is covered by the correct alloy.