330 Stainless Steel: Properties and Key Applications
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Table Of Content
Table Of Content
330 Stainless Steel is classified as an austenitic stainless steel, known for its excellent high-temperature strength and oxidation resistance. This grade is primarily alloyed with chromium (20-25%) and nickel (30-35%), with the addition of small amounts of manganese, silicon, and carbon. The high nickel content enhances its corrosion resistance and ductility, while chromium contributes to its overall strength and oxidation resistance.
Comprehensive Overview
330 Stainless Steel is particularly valued in high-temperature applications due to its ability to maintain strength and resist oxidation at elevated temperatures. Its unique combination of alloying elements results in a material that exhibits excellent thermal stability, making it suitable for environments where thermal cycling occurs.
Key Characteristics:
- High-Temperature Strength: Retains mechanical properties at temperatures up to 1,100°C (2,012°F).
- Oxidation Resistance: Excellent resistance to oxidation in high-temperature environments.
- Ductility: Good formability and weldability, allowing for various fabrication methods.
Advantages:
- Exceptional resistance to scaling and oxidation.
- Suitable for use in extreme environments, such as furnace components and heat exchangers.
- Good weldability, making it versatile for various applications.
Limitations:
- Higher cost compared to other stainless steel grades due to alloying elements.
- Not as resistant to pitting corrosion in chloride environments compared to other stainless steels.
Historically, 330 Stainless Steel has been utilized in applications such as furnace linings, heat exchangers, and other high-temperature industrial processes, establishing its position as a reliable material in demanding environments.
Alternative Names, Standards, and Equivalents
| Standard Organization | Designation/Grade | Country/Region of Origin | Notes/Remarks |
|---|---|---|---|
| UNS | S33000 | USA | Closest equivalent to AISI 330 |
| AISI/SAE | 330 | USA | Commonly used designation |
| ASTM | A240 | USA | Standard specification for stainless steel plates |
| EN | 1.4864 | Europe | European equivalent |
| JIS | SUS330 | Japan | Japanese standard designation |
The equivalences listed above may have minor compositional differences that can affect performance. For instance, while UNS S33000 and AISI 330 are closely related, slight variations in nickel content can influence corrosion resistance and mechanical properties.
Key Properties
Chemical Composition
| Element (Symbol and Name) | Percentage Range (%) |
|---|---|
| Cr (Chromium) | 20.0 - 25.0 |
| Ni (Nickel) | 30.0 - 35.0 |
| Mn (Manganese) | 1.0 - 2.0 |
| Si (Silicon) | 0.5 - 1.0 |
| C (Carbon) | ≤ 0.10 |
The primary alloying elements in 330 Stainless Steel play crucial roles:
- Chromium: Enhances corrosion resistance and contributes to the formation of a protective oxide layer.
- Nickel: Improves ductility and toughness, particularly at elevated temperatures.
- Manganese: Aids in deoxidation and enhances strength.
- Silicon: Improves oxidation resistance and increases strength at high temperatures.
Mechanical Properties
| Property | Condition/Temper | Test Temperature | Typical Value/Range (Metric) | Typical Value/Range (Imperial) | Reference Standard for Test Method |
|---|---|---|---|---|---|
| Tensile Strength | Annealed | Room Temp | 515 - 690 MPa | 75 - 100 ksi | ASTM E8 |
| Yield Strength (0.2% offset) | Annealed | Room Temp | 205 - 310 MPa | 30 - 45 ksi | ASTM E8 |
| Elongation | Annealed | Room Temp | 40 - 50% | 40 - 50% | ASTM E8 |
| Hardness (Rockwell B) | Annealed | Room Temp | 85 - 95 HRB | 85 - 95 HRB | ASTM E18 |
| Impact Strength | Charpy V-notch | -196°C | 40 J | 29.5 ft-lbf | ASTM E23 |
The mechanical properties of 330 Stainless Steel make it suitable for applications requiring high strength and ductility, particularly under thermal stress. Its yield strength and tensile strength ensure structural integrity in high-temperature environments, while its elongation indicates good formability.
Physical Properties
| Property | Condition/Temperature | Value (Metric) | Value (Imperial) |
|---|---|---|---|
| Density | Room Temp | 7.93 g/cm³ | 0.286 lb/in³ |
| Melting Point | - | 1,400 - 1,530°C | 2,552 - 2,786°F |
| Thermal Conductivity | Room Temp | 16.3 W/m·K | 112 BTU·in/(hr·ft²·°F) |
| Specific Heat Capacity | Room Temp | 500 J/kg·K | 0.119 BTU/lb·°F |
| Electrical Resistivity | Room Temp | 0.73 µΩ·m | 0.0000013 Ω·in |
Key physical properties such as thermal conductivity and specific heat capacity are significant for applications involving heat transfer, such as in heat exchangers. The density indicates that while 330 Stainless Steel is relatively heavy, its strength-to-weight ratio is advantageous in structural applications.
Corrosion Resistance
| Corrosive Agent | Concentration (%) | Temperature (°C/°F) | Resistance Rating | Notes |
|---|---|---|---|---|
| Sulfuric Acid | 10 - 30 | 20 - 60 | Good | Risk of pitting |
| Chlorides | 0 - 3 | 20 - 60 | Fair | Susceptible to pitting |
| Acetic Acid | 5 - 20 | 20 - 60 | Good | Resistant to stress corrosion cracking |
| Sea Water | - | 20 - 60 | Fair | Risk of localized corrosion |
330 Stainless Steel exhibits excellent resistance to a variety of corrosive environments, particularly in high-temperature applications. It is particularly effective against oxidation and scaling, making it suitable for furnace applications. However, it is less resistant to pitting corrosion in chloride environments compared to grades like 316L, which is specifically designed for marine applications.
When compared to 316L, 330 Stainless Steel offers superior high-temperature performance but may not perform as well in chloride-rich environments. In contrast, 310 Stainless Steel provides better oxidation resistance but lacks the ductility of 330.
Heat Resistance
| Property/Limit | Temperature (°C) | Temperature (°F) | Remarks |
|---|---|---|---|
| Max Continuous Service Temp | 1,100°C | 2,012°F | Suitable for prolonged exposure |
| Max Intermittent Service Temp | 1,200°C | 2,192°F | Short-term exposure only |
| Scaling Temperature | 1,200°C | 2,192°F | Risk of oxidation above this temp |
| Creep Strength considerations begin | 800°C | 1,472°F | Creep resistance decreases above this temperature |
At elevated temperatures, 330 Stainless Steel maintains its mechanical properties and exhibits excellent oxidation resistance. However, care must be taken to avoid prolonged exposure at temperatures exceeding its maximum continuous service limit to prevent degradation.
Fabrication Properties
Weldability
| Welding Process | Recommended Filler Metal (AWS Classification) | Typical Shielding Gas/Flux | Notes |
|---|---|---|---|
| TIG | ER330 | Argon | Excellent for thin sections |
| MIG | ER330 | Argon + 2% CO2 | Good for thicker sections |
| SMAW | E330 | - | Requires preheat for thick sections |
330 Stainless Steel is well-suited for welding, with the recommended filler metals ensuring compatibility and maintaining mechanical properties. Preheating may be necessary for thicker sections to avoid cracking.
Machinability
| Machining Parameter | 330 Stainless Steel | AISI 1212 | Notes/Tips |
|---|---|---|---|
| Relative Machinability Index | 30 | 100 | Requires slower cutting speeds |
| Typical Cutting Speed (Turning) | 20 m/min | 60 m/min | Use carbide tools for best results |
Machinability is moderate for 330 Stainless Steel, requiring slower cutting speeds and specialized tooling to achieve optimal results.
Formability
330 Stainless Steel exhibits good formability, allowing for cold and hot forming processes. However, due to work hardening, careful control of bending radii and forming techniques is essential to avoid cracking.
Heat Treatment
| Treatment Process | Temperature Range (°C/°F) | Typical Soaking Time | Cooling Method | Primary Purpose / Expected Result |
|---|---|---|---|---|
| Solution Annealing | 1,030 - 1,150°C / 1,886 - 2,102°F | 30 minutes | Air or Water | Dissolve carbides, improve ductility |
| Stress Relief | 600 - 800°C / 1,112 - 1,472°F | 1 hour | Air | Reduce residual stresses |
During heat treatment, 330 Stainless Steel undergoes metallurgical transformations that enhance its ductility and relieve stresses, improving its performance in high-temperature applications.
Typical Applications and End Uses
| Industry/Sector | Specific Application Example | Key Steel Properties Utilized in this Application | Reason for Selection (Brief) |
|---|---|---|---|
| Aerospace | Furnace components | High-temperature strength, oxidation resistance | Essential for durability |
| Chemical Processing | Heat exchangers | Corrosion resistance, thermal stability | Ensures longevity in harsh environments |
| Power Generation | Boiler tubes | High-temperature strength, weldability | Critical for structural integrity |
Other applications include:
- Industrial furnaces
- Heat treatment equipment
- Exhaust systems
The selection of 330 Stainless Steel in these applications is primarily due to its ability to withstand extreme temperatures and corrosive environments, ensuring reliability and safety.
Important Considerations, Selection Criteria, and Further Insights
| Feature/Property | 330 Stainless Steel | 316L Stainless Steel | 310 Stainless Steel | Brief Pro/Con or Trade-off Note |
|---|---|---|---|---|
| Key Mechanical Property | High-temperature strength | Good corrosion resistance | Excellent oxidation resistance | 330 excels in high-temp, 316L in corrosion |
| Key Corrosion Aspect | Fair in chlorides | Excellent in chlorides | Good in high temps | 330 is less resistant to pitting |
| Weldability | Good | Excellent | Good | 330 requires careful preheating |
| Machinability | Moderate | High | Moderate | 330 requires slower speeds |
| Formability | Good | Excellent | Moderate | 330 has work hardening issues |
| Approx. Relative Cost | Higher | Moderate | Higher | Cost varies based on market demand |
| Typical Availability | Moderate | High | Moderate | Availability can affect project timelines |
When selecting 330 Stainless Steel, considerations include its cost-effectiveness, availability, and specific application requirements. While it is more expensive than some alternatives, its performance in high-temperature environments often justifies the investment. Additionally, its magnetic properties are negligible, making it suitable for applications where magnetic interference is a concern.
In summary, 330 Stainless Steel is a versatile material that excels in high-temperature and corrosive environments, making it a preferred choice for various industrial applications. Its unique properties and performance characteristics should be carefully evaluated against project requirements to ensure optimal material selection.