310, 310S & 310H Stainless Steel Fasteners: A Complete Guide to Chemistry, Properties & High‑Temperature Capability

In the world of high‑temperature bolting, 310 stainless steel is the go‑to alloy for applications that reach 1100°C. Its high chromium and nickel content gives it exceptional oxidation resistance—far beyond what 304 or 316 can offer. At RAYCHIN LIMITED, a specialist global manufacturer and supplier of high‑temperature alloy fasteners with decades of in‑house experience, we produce the full family of 310, 310S, and 310H bolts, studs, nuts, and custom parts. This guide covers everything from chemical composition and mechanical properties to the critical differences between the three grades, helping you specify with confidence.

1. What Is 310 Stainless Steel?

What is 310 stainless steel? Alloy 310 is a high‑chromium (25%), high‑nickel (20%) fully austenitic stainless steel. Its chemistry is precisely engineered for high‑temperature oxidation resistance up to 1100°C in continuous service. The dense chromium‑oxide layer that forms on the surface protects the metal from scaling and further attack, making it ideal for furnace hardware, heat exchangers, kilns, and exhaust systems. It is not intended for low‑temperature aqueous corrosion service, where 316 or duplex grades are better suited.

2. 310 vs 310S vs 310H — Understanding the Grades

The 310 vs 310S fasteners distinction is the most frequently encountered. 310S (UNS S31008) is the low‑carbon variant, with carbon restricted to a maximum of 0.08% (compared to 0.25% for standard 310). This low carbon content prevents chromium‑carbide precipitation at grain boundaries during welding or prolonged exposure in the 450–850°C sensitization range, preserving intergranular corrosion resistance. 310H fasteners (UNS S31009) contain a controlled higher carbon content (0.04–0.10%) to provide enhanced creep strength at high temperatures, often specified for pressure vessel bolting and structural applications above 700°C. RAYCHIN stocks all three variants and can advise on the optimal grade for your application.

3. Chemical Compositions of 310, 310S, and 310H

4. 310 Stainless Steel Properties — Mechanical and Physical

310 stainless steel properties at room temperature (solution‑annealed condition per ASTM A276):

• Tensile Strength: ≥ 515 MPa (75 ksi)
• Yield Strength (0.2% offset): ≥ 205 MPa (30 ksi)
• Elongation: ≥ 40%
• Hardness: ≤ 95 HRB

Physical properties include a density of 8.03 g/cm³, melting range of 1400–1455°C, and a mean coefficient of thermal expansion of 19.3 µm/m·°C from 20–1000°C. These values apply broadly to 310, 310S, and 310H; the mechanical properties in the annealed condition are essentially identical.

5. High‑Temperature Capability — 310 and 310S Maximum Temperature

310 stainless steel high temperature performance is its defining feature. The continuous service limit in clean oxidizing atmospheres is 1100°C (2010°F), with intermittent exposure up to 1150°C possible. 310S maximum temperature under load is slightly lower due to its lower carbon content, but for oxidation resistance alone, it matches 310. 310H, with its controlled carbon, provides improved creep strength above 650°C and is often selected for pressure vessel bolting where long‑term stress‑rupture life is critical. For loaded fasteners, a practical upper limit of 800°C is recommended to avoid excessive creep deformation.

6. RAYCHIN's 310, 310S, and 310H Fastener Manufacturing

RAYCHIN LIMITED supplies the complete range of UNS S31000, S31008, and S31009 fasteners to global industries:

• Hex bolts – ASME B18.2.1, DIN 931/933, M6–M48, 1/4″–2″
• Stud bolts and threaded rod – ASME B16.5, DIN 976, M6–M64, 1/4″–2‑1/2″
• Socket head cap screws – ASME B18.3
• Heavy hex nuts and washers
• Custom parts – per your drawings; flanged bolts, stepped studs, furnace hardware

All products are solution‑annealed, with full material certification, PMI testing, and EN 10204 3.1 as standard (3.2 available). High‑temperature anti‑seize coatings can be pre‑applied to prevent galling during assembly.