310 & 310S Fasteners: Complete Technical Data – Tensile Strength, Temperature Limits, Torque, Machining & More

When designing high‑temperature bolted joints for furnaces, heat exchangers, or exhaust systems, having precise 310 and 310S stainless steel property data is essential. RAYCHIN LIMITED, a specialist global manufacturer and supplier of high‑temperature alloy fasteners, provides this authoritative technical reference. We cover all critical mechanical and thermal properties, including tensile and yield strength, hardness, maximum temperature limits, oxidation resistance, thermal expansion, torque values, galling resistance, machining challenges, and heat treatment protocols. This data is drawn from international standards and verified through our own production experience, giving engineers the confidence to design safe, durable bolted connections.

1. Room‑Temperature Mechanical Properties

The baseline strength of 310 and 310S fasteners is established in the solution‑annealed condition. 310 tensile strength and 310 yield strength are moderate compared to hardened alloys, but the primary purpose of 310 is high‑temperature oxidation resistance. Minimum room‑temperature values per ASTM A276 are:

310 hardness is low compared to martensitic or precipitation‑hardened stainless steels, which means 310 fasteners are not intended for applications requiring high preload or tensile strength. Their strength lies in thermal stability and oxidation resistance.

2. High‑Temperature Performance: Maximum Temperature, Oxidation, and Creep

310 stainless steel maximum temperature for continuous service in oxidizing atmospheres is approximately 1100°C (2010°F). Under intermittent service, this can extend to 1150°C. However, for loaded fasteners, practical limits are lower: sustained tensile loading is not recommended above 800°C due to significant strength loss and creep.

310S oxidation resistance is virtually identical to 310. The low‑carbon variant offers no inherent advantage in oxidation rate; its benefit lies in resistance to intergranular corrosion after welding or sensitization. Both grades rely on a dense chromium‑oxide (Cr₂O₃) scale that resists spalling and further oxidation. Silicon, present up to 1.5%, further enhances this protective scale.

310 creep strength and 310 stress rupture properties are moderate compared to nickel‑base superalloys but are adequate for many furnace and exhaust applications. At 650°C, the 1000‑hour stress‑rupture strength is approximately 55 MPa (8 ksi); at 870°C, this drops to roughly 15 MPa (2 ksi). For components under sustained mechanical load at extreme temperatures, nickel‑base alloys such as Inconel 601 or Nimonic 75 may be required.

3. Thermal Expansion and Heat Treatment

310 thermal expansion must be carefully considered in joint design. The mean coefficient of thermal expansion from 20–1000°C is approximately 19.3 µm/m·°C (10.7 µin/in·°F)—significantly higher than that of carbon steel or ferritic stainless steels. This can cause differential expansion stresses in bi‑metallic joints. RAYCHIN's application engineers can assist with joint design to accommodate these effects.

310 heat treatment consists of 310 solution annealed at 1040–1150°C (1900–2100°F), followed by rapid water quenching. This dissolves any chromium carbides and sigma phase, restoring a fully austenitic structure with optimal ductility and corrosion resistance. 310 cannot be hardened by heat treatment; its strength comes from solid‑solution alloying. After prolonged exposure at 600–900°C, sigma phase (a brittle iron‑chromium intermetallic) may form, causing room‑temperature embrittlement. Proper solution annealing reverses this effect.

310 sigma phase embrittlement is a critical risk when fasteners are slowly cooled through or operated in the 600–900°C range. The high chromium content of 310 accelerates sigma phase precipitation compared to lower‑chromium stainless steels. RAYCHIN recommends 310S for such applications to at least minimize the concurrent risk of intergranular carbide sensitization.

4. Torque Values and Tightening Recommendations

Achieving the correct preload for 310 fasteners requires accurate 310 torque values. Because the alloy has relatively low yield strength, over‑torquing can easily cause thread stripping. The 310 bolt tightening torque table below is based on 50% of the minimum yield strength (30 ksi) and a lubricated nut factor K = 0.16.

These values assume clean, lubricated threads with a high‑temperature anti‑seize compound (nickel‑based or ceramic). Always use a calibrated torque wrench with slow, steady application.

5. Galling Resistance and Assembly Best Practices

310 galling resistance is poor—typical of austenitic stainless steels. Under high contact stress, the alloy is highly susceptible to adhesive wear, leading to thread seizure. RAYCHIN recommends the following measures to ensure reliable assembly:

• Use rolled threads rather than cut threads; the smoother surface finish reduces galling tendency.
• Apply a high‑temperature anti‑seize compound—nickel‑based, boron nitride, or cermet‑based lubricants are effective at furnace operating temperatures.
• Pair with a nut of a different alloy—Nitronic 60 nuts on 310 studs are an excellent anti‑galling combination.
• Assemble slowly with calibrated torque wrenches; never use impact tools on 310 fasteners.

6. Machining 310 Stainless Steel

Machining 310 stainless steel requires techniques appropriate for high‑chromium, high‑nickel austenitic alloys. The material work‑hardens rapidly, generates significant heat, and produces tough, stringy chips. RAYCHIN's experienced machinists employ:

• Rigid CNC turning centers with positive‑rake carbide tools
• Moderate cutting speeds (15–25 m/min) and heavy feed rates to minimize work hardening
• High‑pressure coolant (chlorinated oil) for cooling and chip breaking
• Thread rolling rather than cutting for final threads, improving fatigue life and galling resistance

7. RAYCHIN's Technical Support Commitment

Every 310 or 310S fastener from RAYCHIN LIMITED is delivered with a complete quality dossier: chemical analysis, tensile test results, hardness readings, and EN 10204 3.1 certification (3.2 on request). Our application engineers are available to provide customized torque tables, joint design recommendations, and material selection support for your specific high‑temperature environment.