310 Stainless Steel: Properties and Key Applications
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Table Of Content
Table Of Content
310 Stainless Steel is classified as an austenitic stainless steel, known for its high chromium and nickel content, which provides excellent oxidation resistance and high-temperature strength. The primary alloying elements in 310 stainless steel include approximately 24% chromium and 19% nickel, which contribute to its superior corrosion resistance and mechanical properties.
Comprehensive Overview
310 stainless steel is particularly valued for its ability to withstand extreme temperatures and corrosive environments, making it suitable for applications in various industries, including aerospace, chemical processing, and power generation. Its high chromium content enhances its resistance to oxidation and scaling at elevated temperatures, while the nickel content improves its ductility and toughness.
Advantages and Limitations
| Advantages | Limitations |
|---|---|
| Excellent high-temperature strength | Higher cost compared to lower alloy grades |
| Superior oxidation resistance | Limited weldability compared to some other stainless steels |
| Good resistance to sulfuric and phosphoric acids | Susceptible to stress corrosion cracking in certain environments |
| High ductility and toughness | Requires careful handling during fabrication to avoid work hardening |
310 stainless steel holds a significant position in the market due to its unique properties, making it a preferred choice for high-temperature applications. Historically, it has been used in applications such as furnace components, heat exchangers, and gas turbine parts, showcasing its versatility and reliability.
Alternative Names, Standards, and Equivalents
| Standard Organization | Designation/Grade | Country/Region of Origin | Notes/Remarks |
|---|---|---|---|
| UNS | S31000 | USA | Closest equivalent to AISI 310 |
| AISI/SAE | 310 | USA | Commonly used designation |
| ASTM | A240 | USA | Standard specification for stainless steel plates |
| EN | 1.4845 | Europe | Similar properties, minor compositional differences |
| JIS | SUS310 | Japan | Equivalent grade with similar characteristics |
| GB | 00Cr25Ni20 | China | Closest equivalent with slight variations |
The differences between these equivalent grades can affect selection based on specific application requirements, such as temperature limits and corrosion resistance. For example, while 1.4845 offers similar properties, it may have slightly different mechanical characteristics that could influence performance in specific environments.
Key Properties
Chemical Composition
| Element (Symbol and Name) | Percentage Range (%) |
|---|---|
| Cr (Chromium) | 24.0 - 26.0 |
| Ni (Nickel) | 19.0 - 22.0 |
| C (Carbon) | ≤ 0.08 |
| Mn (Manganese) | ≤ 2.0 |
| Si (Silicon) | ≤ 1.0 |
| P (Phosphorus) | ≤ 0.045 |
| S (Sulfur) | ≤ 0.03 |
Chromium is crucial for enhancing corrosion resistance and oxidation resistance, while nickel contributes to the steel's toughness and ductility. The low carbon content minimizes the risk of carbide precipitation, which can lead to intergranular corrosion.
Mechanical Properties
| Property | Condition/Temper | Typical Value/Range (Metric - SI Units) | Typical Value/Range (Imperial Units) | Reference Standard for Test Method |
|---|---|---|---|---|
| Tensile Strength | Annealed | 515 - 750 MPa | 75 - 109 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 | 70 - 90 | ASTM E18 |
| Impact Strength (Charpy) | -20°C | 30 J | 22 ft-lbf | ASTM E23 |
The combination of high tensile and yield strength, along with good elongation, makes 310 stainless steel suitable for applications requiring structural integrity under mechanical loading. Its impact strength at low temperatures ensures reliability in cryogenic applications.
Physical Properties
| Property | Condition/Temperature | Value (Metric - SI Units) | Value (Imperial Units) |
|---|---|---|---|
| Density | Room Temperature | 7.9 g/cm³ | 0.285 lb/in³ |
| Melting Point | - | 1400 - 1450 °C | 2552 - 2642 °F |
| Thermal Conductivity | Room Temperature | 16.2 W/m·K | 112 BTU·in/ft²·h·°F |
| Specific Heat Capacity | Room Temperature | 500 J/kg·K | 0.12 BTU/lb·°F |
| Electrical Resistivity | Room Temperature | 0.72 µΩ·m | 0.0000013 Ω·in |
The density of 310 stainless steel contributes to its strength, while its thermal conductivity and specific heat capacity make it suitable for high-temperature applications where heat transfer is critical.
Corrosion Resistance
| Corrosive Agent | Concentration (%) | Temperature (°C/°F) | Resistance Rating | Notes |
|---|---|---|---|---|
| Chlorides | 3-10 | 20-60 / 68-140 | Fair | Risk of pitting |
| Sulfuric Acid | 10-30 | 20-60 / 68-140 | Good | Resistant at moderate temps |
| Phosphoric Acid | 10-50 | 20-60 / 68-140 | Excellent | Very good resistance |
| Atmospheric Conditions | - | - | Excellent | Resistant to oxidation |
310 stainless steel exhibits excellent resistance to a variety of corrosive environments, particularly in acidic conditions. Its performance against chlorides is moderate, and care should be taken to avoid pitting corrosion. Compared to grades like 304 and 316, 310 offers superior high-temperature oxidation resistance but may not perform as well 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 | Can withstand short-term exposure at higher temps |
| Scaling Temperature | 900 °C | 1652 °F | Begins to oxidize significantly above this temperature |
At elevated temperatures, 310 stainless steel maintains its strength and oxidation resistance, making it ideal for furnace applications and heat exchangers. However, prolonged exposure to temperatures above 1150 °C can lead to scaling and degradation of material properties.
Fabrication Properties
Weldability
| Welding Process | Recommended Filler Metal (AWS Classification) | Typical Shielding Gas/Flux | Notes |
|---|---|---|---|
| TIG | ER310 | Argon | Good for thin sections |
| MIG | ER310 | Argon + CO2 mix | Suitable for thicker sections |
| SMAW | E310 | - | Requires preheat for thick sections |
310 stainless steel can be welded using various methods, but care must be taken to avoid cracking. Preheating and post-weld heat treatment are recommended to relieve stresses and improve weld integrity.
Machinability
| Machining Parameter | 310 Stainless Steel | AISI 1212 | Notes/Tips |
|---|---|---|---|
| Relative Machinability Index | 30% | 100% | Requires slower speeds |
| Typical Cutting Speed | 20-30 m/min | 60-80 m/min | Use carbide tools for best results |
Machinability of 310 stainless steel is lower compared to free-machining steels like AISI 1212. Optimal conditions include using sharp tools and appropriate cutting fluids to minimize work hardening.
Formability
310 stainless steel exhibits good formability, allowing for cold and hot working processes. However, due to its high strength, it may require larger bend radii to avoid cracking during forming operations.
Heat Treatment
| Treatment Process | Temperature Range (°C/°F) | Typical Soaking Time | Cooling Method | Primary Purpose / Expected Result |
|---|---|---|---|---|
| Solution Annealing | 1000 - 1100 °C / 1832 - 2012 °F | 1 hour | Air or water | Dissolve carbides, improve ductility |
| Stress Relief | 600 - 800 °C / 1112 - 1472 °F | 1 hour | Air | Reduce residual stresses |
Heat treatment processes such as solution annealing enhance the ductility and toughness of 310 stainless steel by dissolving carbides and refining the microstructure.
Typical Applications and End Uses
| Industry/Sector | Specific Application Example | Key Steel Properties Utilized in this Application | Reason for Selection (Brief) |
|---|---|---|---|
| Aerospace | Exhaust systems | High-temperature strength, oxidation resistance | Required for extreme conditions |
| Chemical Processing | Heat exchangers | Corrosion resistance, thermal stability | Effective in acidic environments |
| Power Generation | Boiler tubes | High strength, thermal conductivity | Essential for heat transfer |
| Oil and Gas | Flare stacks | High-temperature performance | Safety in extreme conditions |
Other applications include:
- Furnace components
- Kiln linings
- Industrial ovens
- Heat treatment fixtures
The selection of 310 stainless steel in these applications is primarily due to its ability to withstand high temperatures and corrosive environments, ensuring longevity and reliability.
Important Considerations, Selection Criteria, and Further Insights
| Feature/Property | 310 Stainless Steel | AISI 316 | AISI 304 | Brief Pro/Con or Trade-off Note |
|---|---|---|---|---|
| Key Mechanical Property | High strength | Moderate strength | Lower strength | 310 is better for high temps |
| Key Corrosion Aspect | Excellent in acids | Good in chlorides | Fair in acids | 310 excels in high-temperature acids |
| Weldability | Moderate | Good | Excellent | 310 requires more care in welding |
| Machinability | Low | Moderate | High | 310 is harder to machine |
| Formability | Moderate | Good | Excellent | 310 requires larger bend radii |
| Approx. Relative Cost | High | Moderate | Low | Cost reflects performance benefits |
| Typical Availability | Moderate | High | Very High | 304 is the most common stainless steel |
When selecting 310 stainless steel, considerations include its cost-effectiveness, availability, and specific performance requirements in high-temperature and corrosive environments. While it may be more expensive than other grades, its unique properties often justify the investment in critical applications.
In summary, 310 stainless steel is a versatile and robust material, ideal for high-temperature and corrosive applications. Its unique properties make it a preferred choice in various industries, ensuring safety and reliability in demanding environments.