310S Stainless Steel: High-Temperature Properties & Applications

What is 310S Stainless Steel?

310S stainless steel is a high-chromium, high-nickel austenitic stainless steel specifically designed for high-temperature applications. With 25% chromium and 20% nickel, it offers exceptional resistance to oxidation and carburization at elevated temperatures, along with good strength and creep resistance.

The “S” in 310S stands for “stabilized” (low carbon), meaning it has a maximum carbon content of 0.08% (compared to 0.25% for standard 310). This low carbon content provides better resistance to sensitization (grain boundary carbide precipitation) during welding and high-temperature service, improving corrosion resistance in the heat-affected zone.

Sometimes referred to as “25/20 stainless steel” (25% chromium, 20% nickel), 310S is the go-to choice for applications involving continuous temperatures up to 1100 deg C (2010 deg F). It’s widely used in furnaces, heat treatment equipment, power generation, and chemical processing.

Chemical Composition

The chemical composition of 310S stainless steel (UNS S31008 / EN 1.4845) is:

Why the High Chromium + Nickel?

The high chromium and nickel content is what makes 310S so special:

• High Chromium (24-26%): Forms a dense, stable chromium oxide (Cr2O3) layer that provides exceptional oxidation resistance at very high temperatures. The higher the chromium, the more stable the oxide layer at elevated temperatures.
• High Nickel (19-22%): Stabilizes the austenitic structure, improves high-temperature ductility, enhances creep resistance, and contributes to overall corrosion resistance.
• Low Carbon (<=0.08%): Reduces sensitization during welding and high-temperature cycling, maintaining better corrosion resistance.

Mechanical Properties

High-Temperature Strength

What truly distinguishes 310S is its performance at high temperatures:

310S also exhibits good creep and stress rupture properties at temperatures up to about 1000 deg C (1830 deg F), making it suitable for load-bearing applications at high temperatures.

Key Features & Benefits

1. Exceptional High-Temperature Oxidation Resistance

This is 310S’s primary advantage. It resists oxidation (scaling) in continuous service up to:

• 1100 deg C (2010 deg F) in clean, dry air
• 1150 deg C (2100 deg F) for intermittent service (cycling)
• 1000 deg C (1830 deg F) in sulfur-containing atmospheres

The high chromium content forms an extremely stable Cr2O3 protective layer that remains adherent even at very high temperatures and thermal cycling.

2. Good Carburization Resistance

310S resists carburization (carbon diffusion that makes steel brittle) much better than 304 or 316, especially at high temperatures. This makes it valuable for heat treating furnaces, carburizing furnaces, and other high-temperature carbon-rich environments.

3. Excellent High-Temperature Strength and Creep Resistance

The high nickel content gives 310S good strength at elevated temperatures, including resistance to creep (slow deformation under load at high temperature). For structural components operating at high temperatures, 310S maintains its integrity where 304 or 316 would deform or fail.

4. Good General Corrosion Resistance

With 25% chromium and 20% nickel, 310S has excellent corrosion resistance at room temperature - better than 304 and comparable to 316 in many environments. It’s particularly resistant to:

• Atmospheric corrosion
• Mild acids and alkalis
• Oxidizing chemicals
• Aqueous corrosion in many environments

5. Excellent Ductility and Toughness

As an austenitic stainless steel, 310S is highly ductile and tough, even at low temperatures. It can be readily formed, drawn, and fabricated. Its toughness remains excellent even down to cryogenic temperatures.

6. Good Weldability

310S has good weldability thanks to its low carbon content. It can be welded by all standard methods (TIG, MIG, SMAW, etc.) without significant post-weld corrosion issues. Matching 310S filler metal is typically used.

Common Applications

310S stainless steel is the workhorse of high-temperature industries:

Heat Treatment & Furnaces:

• Furnace liners and muffles
• Heat treatment baskets and trays
• Fixtures and jigs for heat treating
• Annealing covers and retorts
• Radiant tubes
• Conveyor belts for furnaces

Power Generation:

• Boiler components
• Superheater tubes
• Steam generator parts
• Exhaust systems for power plants
• Flue gas desulfurization components

Chemical Processing:

• Reactors and pressure vessels
• Piping for high-temperature processes
• Catalyst support grids
• Evaporator and heat exchanger tubes
• Sulfuric acid processing equipment

Petrochemical & Refining:

• Refinery furnace tubes
• Catalytic crackers and reformers
• Hydrocracker components
• High-temperature piping and vessels

Metals Processing:

• Galvanizing and annealing equipment
• Molten metal handling (aluminum, zinc)
• Sintering and calcining equipment
• Die casting dies and components

Automotive & Aerospace:

• Exhaust manifolds and headers
• Catalytic converter housings
• High-temperature sensors
• Aircraft engine components
• Jet engine parts

Other Industries:

• Glass manufacturing equipment
• Cement and lime kiln components
• Incinerators and waste treatment
• Food processing (high-temperature applications)
• Thermal oxidizers

310S vs 304 vs 316 - High-Temperature Comparison

When to Choose 310S

Choose 310S when:

• Operating temperatures exceed 850-900 deg C (1560-1650 deg F)
• You need maximum oxidation resistance at high temperatures
• Carburization is a concern
• The application involves repeated thermal cycling
• Creep resistance at high temperatures is required
• You need good corrosion resistance AND high-temperature performance

Choose 304 when:

• Temperatures are below 850 deg C (1560 deg F)
• General corrosion resistance is the primary need
• Cost is a major factor
• Formability is a priority

Choose 316/316L when:

• Aqueous corrosion (especially chloride pitting) is the main concern
• Temperatures are moderate
• You need high-temperature strength combined with aqueous corrosion resistance

Surface Finishes and Available Forms

310S is available in a wide range of product forms:

• Sheet & Plate - various thicknesses, 2B, No.1, and polished finishes
• Pipe & Tube - seamless and welded, in various sizes and schedules
• Bar & Rod - round, flat, square, hexagonal
• Wire & Wire Mesh - for furnace baskets and screening
• Fittings - elbows, tees, flanges, reducers
• Custom Fabrications - per drawings and specifications

Common surface finishes include:

• No.1 (Hot Rolled) - For high-temperature structural use
• 2B (Cold Rolled) - Smooth, general purpose
• Pickled & Annealed - Standard for tubing and pipe
• Polished - For aesthetic or special applications

Fabrication Considerations

Welding

310S has good weldability. The low carbon content minimizes sensitization. Use 310S or matching filler metal. Preheating is generally not required for most thicknesses. Post-weld annealing (1040-1120 deg C) can be used to restore maximum corrosion resistance and ductility after welding.

Forming

310S can be formed using most conventional methods, including bending, drawing, rolling, and spinning. It work-hardens similarly to 304. For severe forming, intermediate annealing may be necessary. Forming forces are similar to or slightly higher than 304.

Machining

310S machines similar to 304 - it’s “gummy” and work-hardens quickly. Use rigid setups, sharp tools, slower speeds, and heavier feeds. Free-machining variants are not common for 310S.

Heat Treatment

310S cannot be hardened by heat treatment (only by cold working). Solution annealing is performed at 1040-1120 deg C (1900-2050 deg F), followed by rapid quenching or air cooling depending on section size. This treatment dissolves carbides and restores maximum corrosion resistance and ductility.