ASTM A453M-1996 High Temperature Bolting Materials with Coefficients of Expansion Matching Austenitic Stainless Steels

High Temperature Bolts with Austenitic Stainless Steel Matching ASTM A453M-1996 Coefficient of Expansion

Temperature is often considered a villain in terms of the mechanical properties of materials. High temperatures can cause a variety of problems, such as significantly increasing the coefficient of expansion (COE) of mild steels and diminishing the yield strength and ultimate tensile strength. Materials must be chosen with respect to the temperature range within which their application will take place.

In the temperature range of -20°C to 650°C, the most commonly used material for high-temperature bolts are either austenitic stainless steels or highly alloyed steels as defined in ASTM A453M-1996. Unlike mild steels, austenitic stainless steels have a relatively low COE, which means that it deforms less at high temperatures and therefore its applications are ideal for environments exposed to extreme temperature changes. Additionally, austenitic stainless steels do not develop an oxide layer when exposed to high temperatures, which further serves to protect its outer surface and consequently its mechanical integrity.

But even within the austenitic stainless steel family – the group that is often seen as the best option in terms of temperature resistance – there is still considerable variation between different alloys in terms of their COE. This variation is particularly significant in the temperature range of 550°C to 950°C, which could be critical for some applications. ASTM A453M-1996, thus, defines stringent requirements for COE and corrosion fatigue resistance for austenitic stainless steels for bolts intended for high-temperature service in the temperature range of 550°C to 950°C. As stated in the standard, each steel grade must pass a test in which it must have a min yield strength of 895MPa and a min tensile strength of 930MPa, in addition to a COE that is not greater than 6.5×10-6 when tested in air.

There are about 9 types of austenitic stainless steels, known as type 304, 305, 316, 317, 321, 347, 409, 410, and 430, that meet the requirements of ASTM A453M-1996 and are slated for use in high-temperature application. However, further research is required to determine the suitability of these steel types for various applications, most notably in terms of mechanical properties, corrosion resistance and formability. Some austenitic stainless steels, such as 321 and 347, are also known to exhibit outstanding creep resistance at elevated temperatures.

In conclusion, austenitic stainless steels provide the best choice among materials available for use in high-temperature applications due to their inherent low COE, excellent corrosion resistance and good high-temperature strength properties. Among the austenitic stainless steels that meet the requirements of the ASTM A453M-1996 standard, type 304, 305, 316, 317, 321, 347, 409, 410 and 430 are the best for high-temperature bolts. Furthermore, further research is necessary to determine the best suited material for each application.

ASTM A453M-1996 high temperature bolting materials with matching expansion coefficients and austenitic stainless steel is often used to secure parts together in high temperature environments. The A453M-1996 material is a ferritic or martensitic stainless steel that is designed to become tougher at high temperatures and remain resistant to corrosion from hot media, making it an ideal choice for many hot bolting applications. The material is usually made in an annealed condition and has an excellent corrosion resistance in both oxidizing and reducing environments. The A453M-1996 bolting material is also highly resistant to intergranular attack and stress corrosion cracking due to its components of chromium and nickel and to its higher temperature stability.

In addition to its highly resistant properties, the A453M-1996 material provides an ideal combination of strength and ductility. The material’s higher temperature strength provides significantly increased clamping pressures and loads, while the austenitic stainless steel components provide improved repeatability of pre-torque and yield torque.

For screws, nuts and bolts of any size, A453M-1996 bolting material is ideal because of its long-term reliability and strength. Its high temperature properties make it a perfect choice for applications exposed to high temperatures or temperatures near the melting point of aluminum or brass parts, or any combination of other materials.

For any bolting application, whether it’s a large quantity of bolts or just a few, the A453M-1996 material is sure to give you a product that stands the test of time. The material’s compatibility with austenitic stainless steel and its expansion coefficients ensures that your components will stay securely together in most high temperature applications.