High-temperature Stud Bolts: Materials and How to Select Fasteners

What Are “High-Temperature” Stud Bolts?

High‐temperature stud bolts are fasteners designed to retain mechanical strength, dimensional stability, and corrosion/oxidation resistance when exposed to elevated temperatures—typically from 300 °C (572 °F) up to 700 °C (1292 °F) or above. Standard carbon‐steel or low‐alloy studs lose strength or creep at these temperatures, so specialized alloys are used.

For Regular stainless steel and alloy steel fasteners, their upper limit of service temperature is 400°C. When the temperature exceeds 400°C, various properties of the fasteners will decline precipitously. What we refer to as high – temperature fasteners start from 400°C and go up to 1200°C. We can provide fasteners with a service temperature within this range. However, the practical application and raw materials of high – temperature fasteners involve an extremely complex and rigorous process. It covers aspects such as the coefficient of expansion, anti – corrosion and rust – prevention properties, mechanical properties at high temperatures, high – temperature anti – loosening, and high – temperature disassembly of fasteners. Our company can provide professional technical consultations for customers to ensure the application of high – temperature fasteners. Our high – temperature fasteners are mainly applied in heat – treatment equipment, steam turbines, engines, injection molding and hot extrusion equipment, etc. The materials of high – temperature fasteners provided by our company mainly include precipitation – hardening stainless steel, high – temperature stainless steel, and special alloy steel.

Typical High-Temperature Stud-Bolt Materials & Grades introduction

1,Alloy A286 (EN 1.4980 / UNS S66286) ASTM A453 grade 660

• Designation:
  • EN/DIN: 1.4980
  • UNS: S66286
  • ASTM A453 Grade 660 (Classes A, B, C, D)
• Temperature Capability: Up to 650–700 °C (1200–1300 °F) continuous; short‐term up to 760 °C (1400 °F)
• Mechanism: Precipitation‐hardenable austenitic stainless; strengthened by Ni–Cr–Ti precipitates
• Mechanical Properties (Class B typical, aged):
  • Tensile ≥ 930 MPa (135 ksi) at 20 °C
  • Yield ≥ 620 MPa (90 ksi) at 20 °C
  • % Elongation ≥ 25%
  • Creep rupture life (~100 h) at 650 °C: ~70–100 MPa stress
• Applications: Turbine exhausts, steam piping, petrochemical heaters, high‐temp flange bolting
• Standards: ASTM A453 (bolt), A453 covers heat‐treated condition; nuts per ASTM A453 grade 660 ; washers per ANSI B18.22.1

2 Inconel® (Nickel-Chromium Alloys) Stud bolt

Several Inconel alloys are popular for stud-bolt applications:

Note: For typical high-temperature flange bolting up to 600–650 °C, X-750 or 718 are the workhorses. For service above 650 °C (or more aggressive corrosion), shift to 625 or specialty “Alloy” grades.

3,Stainless Steels (High-Alloy, Solid-Solution)

• 316H/321/347 Stainless:
  • Service up to ~550 °C
  • 316H: Slightly higher C version of 316 for creep resistance
  • SS321 ASTM A193 B8C /SS347.ASTM A193 B8T : Ti or Nb stabilized, fewer problems with carbide precipitation at 550 °C, but strength still lower than A286
• ASTM A193 B8/B8M (304/316 stainless) – service up to ~550 °C (low strength)

4,High-Temp Carbon / Low-Alloy Steels

ASTM A193 B16 (2½ Cr—1 Mo steel) – service up to ~500 °C

ASTM A193 B7 Stud bolt

Stud Bolt material grade table for different temperatures

By following these guidelines—selecting the correct alloy/grade, confirming standard compliance, and ensuring proper installation—you can ensure reliable, long-life performance for bolting in high‐temperature applications.