Stainless steel 310H (UNS S31009)

Stainless steel 310H (UNS S31009) is a high chromium-nickel austenitic stainless steel widely used in high temperature and corrosive environments due to its excellent resistance to high temperature, oxidation and corrosion. The following are its main application areas and detailed descriptions:

1. High temperature heat treatment industry

Application scenarios: furnace components, radiant tubes, muffle tanks, heat treatment brackets, burners, etc.

Detailed description:

310H has high chromium (24-26%) and nickel (19-22%) contents, which enable it to maintain excellent oxidation resistance and carburization resistance at continuous high temperatures (up to 1150°C). Commonly used in:

Continuous annealing furnace: protect steel from oxidation during annealing.

Carburizing furnace: resist carbon penetration and extend component life.

Sintering equipment: withstand high temperature reducing atmosphere in powder metallurgy.

2. Petrochemical and refining

Application scenarios: catalytic cracking unit, reforming furnace tube, heat exchanger, sulfur recovery unit.

Detailed description:

310H can resist sulfidation, oxidation and carburization, and is suitable for:

Cracking furnace tubes: resist coking and thermal fatigue in high-temperature hydrocarbon cracking environments.

Sulfur recovery unit (Claus process): resists corrosion from hydrogen sulfide and sulfur dioxide.

Ethylene production: strong stability in high-temperature steam environments.

3. Power and Energy

Application scenarios: boiler components, superheater tubes, gas turbine combustion chambers, biomass power generation equipment.

Detailed description:

Coal/gas-fired boilers: used in high-temperature flue gas areas (such as superheater hangers), resisting coal ash corrosion.

Biomass combustion: resists chloride and alkali metal corrosion (such as KCl, NaCl).

Nuclear power: high-temperature pipelines of some auxiliary systems (non-core components).

4. Chemical processing industry

Application scenarios: reactors, distillation towers, pipelines, pickling equipment.

Detailed description:

Performs well in strong acid (such as nitric acid, organic acid) and mixed acid environments, but please note:

Limitations: Not suitable for reducing acid (such as hydrochloric acid) or halogen environments.

Typical uses: heating coils in nitric acid production, phthalic anhydride reactor linings.

5. Glass and ceramic manufacturing

Application scenarios: glass melting furnace components, ceramic sintering brackets, molds.

Detailed description:

Glass fiber production: used for support structures around platinum-rhodium alloy leak plates, resistant to high-temperature oxidation.

Ceramic sintering: as a kiln material, it resists repeated thermal cycles (low thermal expansion coefficient).

6. Aerospace

Application scenarios: engine exhaust components, afterburner linings.

Detailed description:

310H can be used as a secondary material in intermittent ultra-high temperatures (such as jet engine tail nozzles) to supplement nickel-based alloys and reduce costs.

7. Environmental protection and waste treatment

Application scenarios: garbage incinerators, hazardous waste treatment equipment.

Detailed description:

Resistant to corrosion by dioxins, chlorides and heavy metal vapors, used for:

Incinerator lining: resistant to acidic gases (SO₂, HCl) and fly ash erosion.

Flue gas duct: anti-corrosion in high temperature sections.

8. Food processing (special scenarios)

Application scenarios: high temperature baking equipment, fermentation tank heating elements.

Detailed description:

Because 310H does not contain molybdenum, it may not be as good as 316L in chloride environments, but it is suitable for:

High temperature dryers: pollution-free and resistant to food acid vapors.

Notes: 

1. Welding performance: 310H special welding materials (such as ER310H) are required to avoid intergranular corrosion.

2. Economical: The cost is higher than 304/316, and it is usually only used to replace nickel-based alloys in extremely high temperature or corrosive environments.

3. The core advantage of 310H is its high temperature stability, and its application selection needs to balance temperature, medium composition and cost.

Stainless steel 310S (UNS S31008)

Stainless steel 310S (UNS S31008) is a high alloy austenitic stainless steel, which is widely used in high temperature and corrosive environments due to its excellent high temperature resistance, oxidation resistance and corrosion resistance. The following are its main application areas and detailed descriptions:

1. High temperature heat treatment equipment

Detailed description:

310S can still maintain excellent oxidation resistance and strength at high temperatures (up to 1150°C), so it is often used for:

Furnace parts: such as radiation tubes, muffle tanks, furnace rollers, etc., which are exposed to high temperature environments for a long time.

Heat treatment fixtures: used to fix workpieces in quenching, annealing and other processes to avoid failure due to thermal deformation.

Burner parts: such as combustion chamber linings, which can withstand high temperature oxidation of fuel gas.

Advantages: High chromium (25%) and nickel (20%) content form a stable chromium oxide protective layer to prevent further oxidation.

2. Petrochemical and refining equipment

Detailed description:

Used for corrosive media and high temperature and high pressure environments:

Cracking furnace tubes: withstand high temperature hydrocarbon corrosion in ethylene cracking units.

Catalytic cracking unit: such as reactor lining, cyclone separator, resisting hydrogen sulfide and acid gas corrosion.

Heat exchanger: used for heat exchange of high-temperature corrosive fluids (such as sulfuric acid and nitric acid).

Advantages: resistant to sulfide and chloride stress corrosion cracking, better than ordinary 304/316 stainless steel.

3. Power and energy industry

Detailed description:

Boiler components: such as superheater tubes and combustion chamber linings, resistant to high-temperature flue gas corrosion from coal or gas.

Nuclear power equipment: some non-core auxiliary system components that need to be resistant to high temperatures.

Waste incinerator: resisting chlorine and acid gas corrosion generated by incineration.

Advantages: strong stability in a cyclic redox environment.

4. Glass and ceramic manufacturing

Detailed description:

Glass melting furnace: used for crucibles, molds, and conveyor rollers, resistant to molten glass erosion (above 1400°C).

Ceramic sintering furnace: kiln cars, brackets, etc. need to withstand repeated high-temperature heating-cooling cycles.

Advantages: Low pollution (avoid contamination of glass/ceramic products), not easy to deform at high temperature.

5. Chemical processing equipment

Detailed description:

Reactor and pipeline: handle strong acid (such as concentrated nitric acid), strong alkali or mixed chemical media.

Catalyst carrier: withstand high temperature corrosion in fertilizer or petrochemical catalytic reactions.

Advantages: Strong resistance to intergranular corrosion and pitting.

6. Food and pharmaceutical industry (special scenarios)

Detailed description:

Mainly used for high-temperature sterilization equipment:

Sterilizer liner: withstand chemical corrosion from high-pressure steam (>120℃) and frequent cleaning.

Drying equipment: such as the high-temperature area of the spray drying tower.

Advantages: Meet food-grade hygiene standards (surface polishing required), no risk of metal ion migration.

7. Environmental protection and waste gas treatment

Detailed description:

Flue gas desulfurization (FGD) system: absorber internal components, resist chloride ion corrosion in wet desulfurization.

Waste gas incineration device: high temperature part when treating waste gas containing VOCs or acid.

Advantages: more adaptable to high chloride ion environment than 316L.

8. Aerospace and special fields

Detailed description:

Rocket engine parts: such as nozzle bushings, short-term tolerance to extremely high temperatures.

High temperature sensor sheath: protect thermocouples from long-term operation in extreme environments.

Advantages: low thermal expansion coefficient, reducing thermal fatigue.

Notes:

1. Cost considerations: 310S is expensive due to its high nickel content, and is usually only used to replace ordinary stainless steel in extreme environments.

2. Processing difficulty: high hardness requires special tools, and the interlayer temperature needs to be controlled during welding to avoid carbide precipitation.

3. The core value of 310S lies in its dual tolerance to "high temperature + corrosion", making it an irreplaceable material choice in the above fields.

310H vs 310S

Stainless steel 310H (UNS S31009) and 310S (UNS S31008) belong to the austenitic heat-resistant stainless steel series. The main difference lies in the carbon content and high-temperature performance, so the application areas are different.

1. Composition and performance differences:

Stainless steel 310H (UNS S31009):

1. Carbon content: 0.04–0.10% (enhanced high temperature strength);

2. High temperature performance: strong creep resistance, high endurance strength;

3. Weldability: need to be cautious (high carbon can easily lead to sensitization);

Stainless steel 310S (UNS S31008):

1. Carbon content: ≤0.08% (better corrosion resistance);

2. High temperature performance: good oxidation resistance, but low high temperature strength;

3. Weldability: easier to weld (low carbon reduces carbide precipitation)

2. Application field comparison

Typical applications of 310H

High temperature pressure-bearing parts:

Petrochemical industry: cracking furnace tubes, converter parts (need to withstand high temperature + stress).

Power industry: boiler burners, superheater tubes (operating temperature can reach 1100°C).

Heat treatment equipment: high temperature furnace rollers, muffle tanks (need to resist creep).

Key requirements: maintain structural strength in long-term high temperature environments (such as >800°C).

Typical applications of 310S

Anti-oxidation but low-stress environments:

Food industry: oven liner, baking molds (resistant to high temperature oxidation, no need for high mechanical strength).

Chemical containers: corrosive medium storage tanks (low carbon reduces the risk of intergranular corrosion).

General heat-resistant parts: heat exchanger pipes, flue linings (temperature ≤1000°C).

Key requirements: corrosion resistance, easy forming or welding, and low high temperature stress scenarios.

3. Selection recommendations

Choose 310H: when the equipment needs to withstand mechanical loads for a long time at high temperatures (such as furnace tubes, support parts).

Choose 310S: when anti-oxidation/corrosion is the main focus, or welding processing is required (such as containers, non-pressure-bearing parts).

Note: 

Under extremely high temperatures (>1000°C), the oxidation resistance of the two is similar, but the strength advantage of 310H is more significant.

Summary

The difference between 310H and 310S is essentially the choice of "strength first" and "corrosion resistance/process first", which needs to be determined according to the temperature, stress and processing requirements of the specific working conditions.