310S Stainless Steel: Properties and Key Applications

Table Of Content

Table Of Content

310S stainless steel is an austenitic stainless steel known for its excellent high-temperature strength and oxidation resistance. It is primarily composed of iron, chromium, and nickel, with a low carbon content that enhances its weldability and resistance to intergranular corrosion. The primary alloying elements include:

  • Chromium (Cr): Typically 24-26%, which provides corrosion resistance and contributes to the steel's overall strength.
  • Nickel (Ni): Usually 19-22%, which enhances toughness and ductility, especially at elevated temperatures.
  • Molybdenum (Mo): Present in small amounts (up to 0.75%), which improves resistance to pitting and crevice corrosion.

Key Characteristics

310S stainless steel is characterized by its:
- High-temperature resistance: Suitable for applications involving temperatures up to 1150°C (2100°F).
- Corrosion resistance: Excellent resistance to oxidation and sulfidation.
- Good weldability: Low carbon content minimizes the risk of carbide precipitation during welding.

Advantages and Limitations

Advantages:
- Exceptional resistance to oxidation and corrosion at high temperatures.
- Good mechanical properties at elevated temperatures.
- Excellent weldability and formability.

Limitations:
- Higher cost compared to lower-grade stainless steels.
- Not suitable for applications involving strong reducing environments.

Historically, 310S has been widely used in industries such as petrochemical, power generation, and food processing due to its unique properties.

Alternative Names, Standards, and Equivalents

Standard Organization Designation/Grade Country/Region of Origin Notes/Remarks
UNS S31008 USA Closest equivalent to AISI 310
AISI/SAE 310S USA Low carbon variant of 310
ASTM A240 USA Standard specification for stainless steel plates
EN 1.4845 Europe Equivalent in European standards
JIS SUS310S Japan Japanese standard designation
GB 00Cr25Ni20 China Chinese equivalent with minor compositional differences

The differences between these equivalents can affect performance in specific applications. For instance, while S31008 and SUS310S are similar, variations in nickel content can influence corrosion resistance in certain environments.

Key Properties

Chemical Composition

Element (Symbol and Name) Percentage Range (%)
Fe (Iron) Balance
Cr (Chromium) 24.0 - 26.0
Ni (Nickel) 19.0 - 22.0
Mo (Molybdenum) 0.0 - 0.75
C (Carbon) ≤ 0.08
Mn (Manganese) ≤ 2.0
Si (Silicon) ≤ 1.0
P (Phosphorus) ≤ 0.045
S (Sulfur) ≤ 0.03

The primary role of chromium is to enhance corrosion resistance, while nickel improves toughness and ductility. Molybdenum contributes to pitting resistance, making 310S suitable for harsh environments.

Mechanical Properties

Property Condition/Temper Typical Value/Range (Metric) Typical Value/Range (Imperial) Reference Standard for Test Method
Tensile Strength Annealed 520 - 720 MPa 75 - 104 ksi ASTM E8
Yield Strength (0.2% offset) Annealed 205 - 310 MPa 30 - 45 ksi ASTM E8
Elongation Annealed 40 - 50% 40 - 50% ASTM E8
Hardness (Rockwell B) Annealed 70 - 90 HRB 70 - 90 HRB ASTM E18
Impact Strength -20°C (-4°F) 40 J 30 ft-lbf ASTM E23

The combination of high tensile and yield strength, along with good elongation, makes 310S suitable for applications requiring structural integrity under mechanical loading.

Physical Properties

Property Condition/Temperature Value (Metric) Value (Imperial)
Density Room Temperature 7.93 g/cm³ 0.286 lb/in³
Melting Point - 1400 - 1450 °C 2550 - 2642 °F
Thermal Conductivity Room Temperature 16.2 W/m·K 112 BTU·in/h·ft²·°F
Specific Heat Capacity Room Temperature 500 J/kg·K 0.12 BTU/lb·°F
Electrical Resistivity Room Temperature 0.72 µΩ·m 0.72 µΩ·in

The density and melting point indicate that 310S can withstand high temperatures, making it suitable for applications in extreme environments. Its thermal conductivity is moderate, which is beneficial for applications requiring heat retention.

Corrosion Resistance

Corrosive Agent Concentration (%) Temperature (°C/°F) Resistance Rating Notes
Chlorides 0 - 10 20 - 60 Good Risk of pitting
Sulfuric Acid 0 - 10 20 - 50 Fair Susceptible to SCC
Acetic Acid 0 - 10 20 - 60 Good Moderate resistance
Sea Water - 20 - 30 Excellent Resistant to corrosion

310S stainless steel exhibits excellent resistance to oxidation and corrosion in various environments, including atmospheric, acidic, and saline conditions. However, it can be susceptible to stress corrosion cracking (SCC) in chloride environments.

When compared to grades like 316L, which contains molybdenum for enhanced pitting resistance, 310S may perform better in high-temperature applications but may not be as effective in chloride-rich environments.

Heat Resistance

Property/Limit Temperature (°C) Temperature (°F) Remarks
Max Continuous Service Temp 1150 °C 2100 °F Suitable for high-temperature applications
Max Intermittent Service Temp 1050 °C 1922 °F Short-term exposure only
Scaling Temperature 900 °C 1652 °F Risk of oxidation beyond this point

310S maintains its strength and oxidation resistance at elevated temperatures, making it ideal for furnace components and heat exchangers. However, prolonged exposure beyond its maximum service temperature can lead to scaling and reduced mechanical properties.

Fabrication Properties

Weldability

Welding Process Recommended Filler Metal (AWS Classification) Typical Shielding Gas/Flux Notes
TIG ER310S Argon Excellent for thin sections
MIG ER310 Argon + CO2 Good for thicker sections
SMAW E310-16 - Suitable for all positions

310S is highly weldable, with recommended filler metals that match its composition. Pre- and post-weld heat treatment can enhance the quality of welds and reduce the risk of cracking.

Machinability

Machining Parameter 310S AISI 1212 Notes/Tips
Relative Machinability Index 30% 100% Requires slower cutting speeds
Typical Cutting Speed 20 m/min 60 m/min Use carbide tools for best results

Machining 310S can be challenging due to its toughness and work hardening characteristics. Optimal conditions include using sharp tools and slower cutting speeds to prevent excessive wear.

Formability

310S exhibits good formability, allowing for cold and hot working. However, its work hardening rate can lead to challenges in forming complex shapes. Recommended bend radii should be larger than those for lower grades to avoid cracking.

Heat Treatment

Treatment Process Temperature Range (°C/°F) Typical Soaking Time Cooling Method Primary Purpose / Expected Result
Annealing 1050 - 1150 °C / 1922 - 2100 °F 1 - 2 hours Air or water Relieve stresses, improve ductility
Solution Treatment 1000 - 1100 °C / 1832 - 2012 °F 30 minutes Water Enhance corrosion resistance

Heat treatment processes like annealing can significantly improve the ductility and toughness of 310S, making it more suitable for demanding applications.

Typical Applications and End Uses

Industry/Sector Specific Application Example Key Steel Properties Utilized in this Application Reason for Selection (Brief)
Petrochemical Heat exchangers High-temperature strength, corrosion resistance Essential for durability
Power Generation Boiler components Oxidation resistance, mechanical strength Critical for efficiency
Food Processing Ovens and furnaces Cleanliness, high-temperature stability Meets hygiene standards
Aerospace Exhaust systems Lightweight, high strength Reduces weight while maintaining performance

310S is chosen for applications requiring high-temperature stability and resistance to corrosive environments, making it ideal for industries where reliability is paramount.

Important Considerations, Selection Criteria, and Further Insights

Feature/Property 310S 316L 321 Brief Pro/Con or Trade-off Note
Key Mechanical Property High tensile strength Good corrosion resistance Excellent high-temp stability 310S is stronger at high temps
Key Corrosion Aspect Good in high temps Better in chloride environments Good in high temps 316L excels in saline conditions
Weldability Excellent Good Fair 310S is easier to weld
Machinability Moderate High Low 316L is easier to machine
Approx. Relative Cost Moderate Higher Moderate Cost varies by market conditions
Typical Availability Common Very common Less common 310S is widely available

When selecting 310S, consider its high-temperature performance and corrosion resistance against the specific requirements of the application. While it may be more expensive than lower grades, its durability can lead to lower maintenance costs in the long run. Additionally, its availability in various forms (sheets, plates, pipes) makes it a versatile choice for many engineering applications.

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