If you’re dealing with high-heat environments or aggressive industrial processes, you may find your standard stainless steel parts failing faster than expected. That leads to lost time, higher maintenance costs, and performance issues. You need a material that stays strong under heat and pressure. That’s where 310 stainless steel comes in.
This guide breaks down what makes 310 stainless steel unique. You’ll learn how it’s used, what it’s made of, and when to choose it over other types.
What Is 310 Stainless Steel?
310 stainless steel is an austenitic stainless steel. It belongs to the 300 series, known for its corrosion resistance and good strength. Among them, 310 offers better high-temperature strength than types 304 or 316.
This alloy is designed to work in heat-intensive applications. It stays stable and resists scaling even when exposed to temperatures above 1000°F. That makes it a reliable choice for heat exchangers, furnaces, and thermal processing equipment.
The UNS number for 310 stainless steel is S31000. A common high-performance version, 310S, is labeled as S31008. These grades are recognized in several industry standards.
In ASTM specifications, you’ll find 310 listed under standards such as ASTM A240 (for sheet and plate) and ASTM A312 (for pipe). These specs help ensure the material meets performance expectations in critical applications.
化学組成
310 stainless steel gets its strength and heat resistance from its alloy mix. The main elements are chromium and nickel, with several other minor elements contributing to its structure.
Major Elements
- Chromium (24–26%) improves oxidation resistance. It forms a stable oxide layer that protects the surface in extreme heat.
- Nickel (19–22%) enhances ductility and toughness. It also stabilizes the austenitic structure, which helps the material stay strong at high temperatures.
Minor Elements
- Manganese (up to 2%) helps with hot working and improves toughness.
- Silicon (up to 1.5%) improves oxidation resistance and adds to the strength.
- Carbon (up to 0.25%) increases hardness and strength. But in high amounts, it can lower corrosion resistance, so it’s carefully controlled.
物理的および機械的特性
310 stainless steel offers a good mix of strength, hardness, and thermal performance. These traits make it suitable for both structural and high-temperature uses.
引張強度と降伏強度
310 stainless steel has a typical tensile strength of around 75,000 psi and a yield strength of about 30,000 psi. These values mean the material can withstand strong pulling forces without permanent deformation.
Even at high temperatures, it holds its strength better than many other stainless steels. This makes it dependable in heat treatment or thermal cycling environments.
Hardness and Toughness
On the Brinell scale, the hardness of 310 is around 150–190 HBW. It’s not as hard as martensitic grades but offers a good balance between toughness and wear resistance.
The alloy remains tough and crack-resistant even in cryogenic or elevated temperatures. That makes it a safe choice where mechanical shock or stress is possible.
Density and Melting Point
- 密度: 7.9 g/cm³ (or 0.285 lb/in³)
- Melting range: Between 2470°F and 2550°F (1355°C to 1400°C)
These values show that the material is stable under extreme conditions, and it doesn’t lose shape or integrity easily under heat.
熱伝導率と熱膨張
- 熱伝導率: Around 14.2 W/m·K at 100°C
- (Lower than carbon steel, so it conducts heat more slowly)
- Thermal expansion: Around 15.9 µm/m·°C
This lower thermal conductivity helps reduce heat transfer in high-temperature systems. The moderate expansion rate must be considered in assembly design, especially with dissimilar materials.
耐腐食性
310 stainless steel is best known for its strong resistance to oxidation and heat. It performs well in many harsh environments, especially where high temperatures are involved.
Oxidation Resistance at High Temperatures
310 stainless steel resists oxidation in air at temperatures up to 2000°F (1093°C). The high chromium and nickel levels form a protective oxide layer on the surface. This layer prevents further reaction between the metal and oxygen.
Even when exposed to heat over long periods, the alloy maintains structural stability. That’s why it’s often used in furnace parts and heat shields.
Performance in Sulfur and Nitrogen Atmospheres
310 performs well in air and neutral environments. However, it shows reduced resistance in sulfur-rich or low-oxygen atmospheres. Sulfur can break down the protective oxide layer, leading to corrosion.
In nitrogen-rich settings, the material generally holds up well. But if the environment is both sulfur- and nitrogen-rich, it’s better to use a more specialized alloy.
Limitations in Marine Environments
310 stainless steel is not recommended for marine or chloride-rich settings. Its corrosion resistance in seawater is lower compared to 316 stainless steel.
In coastal or underwater use, chloride ions can cause pitting and crevice corrosion. That limits its effectiveness in applications near saltwater.
Heat Resistance Capabilities
310 stainless steel is designed to handle long-term exposure to high heat. Its structure remains stable under both continuous and cycling thermal loads.
Working Temperature Range
This alloy performs well in temperatures up to 2000°F (1093°C). It can handle even higher temperatures for short periods. However, for long-term use, it’s best to keep it below 2000°F to avoid loss of strength.
In lower temperature ranges, such as below 1500°F, the material retains both strength and corrosion resistance. This flexibility allows it to fit a wide range of high-temperature uses.
Performance in Intermittent and Continuous Service
In intermittent service, where temperatures rise and fall repeatedly, 310 performs reliably without cracking or scaling. The austenitic structure gives it good resistance to thermal shock.
In continuous service, it maintains oxidation resistance and mechanical strength over long durations. That’s a key reason it’s chosen for heat exchangers and burner components.
Fabrication and Workability
310 stainless steel is workable but requires the right techniques. Its high nickel and chromium content affects how it behaves during machining and forming.
加工性
Machining 310 is harder than working with standard grades like 304. The high alloy content increases tool wear. Use sharp tools, low speeds, and plenty of coolant to reduce heat.
It’s best to machine it in an annealed condition. This helps reduce hardening and avoids surface cracking.
Weldability and Welding Methods
310 offers good weldability with most standard methods. ティグ, ミグそして stick welding (SMAW) are all suitable.
Use filler metals like 310 or 309 stainless for strong weld joints. To prevent cracking, avoid high heat inputs and let parts cool slowly after welding.
Forming and Bending Behavior
310 can be 形成 and bent using standard methods, but it takes more force than low-alloy steels. The high strength of the material requires heavier tooling.
To avoid cracking during tight bends, keep the bend radius larger than the sheet thickness. It’s also helpful to preheat thick sections if cold bending is difficult.
Cutting and Drilling Tips
Use carbide tools or high-speed steel (HSS) bits for 掘削. Slow speeds and steady feed pressure work best. Apply cooling fluid to avoid heat buildup.
プラズマ, レーザー、 または ウォータージェット切断 is preferred for cutting. They give clean edges and reduce the chance of distortion or heat-affected zones.
| プロパティ | 価値 |
|---|---|
| UNS Designation | S31000 (310), S31008 (310S) |
| ASTM規格 | ASTM A240 (Sheet/Plate), ASTM A312 (Pipe) |
| 抗張力 | Approx. 75,000 psi |
| 降伏強度 | Approx. 30,000 psi |
| 硬度 | 150–190 HBW (Brinell) |
| Toughness | High at low and high temperatures |
| 密度 | 7.9 g/cm³ (0.285 lb/in³) |
| 融点 | 2470°F–2550°F (1355°C–1400°C) |
| 熱伝導率 | 14.2 W/m·K at 100°C |
| 熱膨張 | 15.9 µm/m·°C |
| クロム含有量 | 24–26% |
| ニッケル含有量 | 19–22% |
| Manganese Content | Up to 2% |
| Silicon Content | Up to 1.5% |
| 炭素含有量 | Up to 0.25% |
| 耐酸化性 | Up to 2000°F (1093°C) in air |
| 耐腐食性 | Good in air, limited in marine or chloride environments |
| 加工性 | Low – needs slow speed, sharp tools, and coolant |
| 溶接性 | Good – TIG, MIG, SMAW; use 310 or 309 filler |
| 成形性 | Moderate – requires higher force, large bend radius |
| Cutting Methods | Laser, plasma, waterjet preferred |
| 一般的な用途 | Furnaces, muffles, radiant tubes, heat exchangers, thermal baskets |
Heat Treatment and Annealing
熱処理 can change how 310 stainless steel performs. It’s mainly used to soften the material, improve ductility, or relieve internal stress after forming or welding.
Recommended Heat Treatment Procedures
For 310 stainless steel, annealing is the most common heat treatment. The process involves heating the metal to 1900–2100°F (1040–1150°C). Then it must be rapidly cooled, usually by water quenching or air cooling.
This method helps restore ductility and reduces the effect of work hardening. It should always be done in a clean environment to avoid scaling or surface oxidation.
Effects on Mechanical Properties
Annealing lowers hardness and increases ductility. This makes the material easier to form, bend, or machine.
However, it also reduces tensile and yield strength. After annealing, the steel becomes more flexible but slightly less strong. That trade-off is acceptable in many forming or welding applications.
When and Why to Use Annealing？
用途 アニール after working in a heavy, cold environment to reduce stress and restore workability. It is also helpful after welding to prevent cracking in the heat-affected zone.
If the part needs to maintain formability for future bending, annealing will help avoid unwanted fractures or tool wear during fabrication.
表面仕上げ
について 表面仕上げ of 310 stainless steel affects both appearance and performance. Different finishes can improve corrosion resistance, ease of cleaning, or visual appeal.
Common Finishes (2B, BA, No.4, Mirror)
- 2B finish: A smooth, dull finish with light reflectivity. It’s common for industrial parts to offer good corrosion resistance.
- BA (Bright Annealed): A bright, reflective finish created in a controlled atmosphere furnace. Used where a clean look and better corrosion resistance are needed.
- No.4 finish: A brushed, directional grain finish. Common in architectural and kitchen applications.
- Mirror finish: Highly polished and reflective. Often used for decorative parts or surfaces requiring easy cleaning.
Pickling, Passivation, and Polishing
- 漬物: Removes scale, oxides, and welding discoloration using acid solutions. It helps restore a clean, corrosion-resistant surface.
- 不動態化: Enhances the natural chromium oxide layer by removing free iron from the surface. Improves corrosion resistance.
- 研磨: Smooths the surface and increases shine. It can also reduce dirt buildup and make cleaning easier.
産業用途
310 stainless steel is built for demanding environments. Its strength and heat resistance make it a good fit for many high-temperature and corrosive settings.
Heat Exchangers and Boilers
310 is used in tubes, plates, and headers in heat exchangers and boilers. It resists scaling and holds shape under thermal stress. That helps maintain system efficiency and safety over time.
Kilns and Furnaces
In kilns, furnace liners, and burner parts, 310 stands up to high heat without warping. It keeps mechanical strength even after long exposure to temperatures above 1800°F. That reduces downtime and replacement costs.
Cryogenic Components
Though known for high-temperature use, 310 also performs well at cryogenic temperatures. It stays tough and crack-resistant when exposed to freezing conditions, which is useful in some gas processing and storage systems.
Petrochemical and Refining Equipment
310 is often found in refinery burners, piping, and flue liners. It resists oxidation and carburization in environments with hot gases and corrosive chemicals. That makes it suitable for high-pressure, high-heat processing lines.
Comparison with Other Stainless Steels
Choosing the right stainless steel depends on the service conditions. Here’s how 310 compares to more common grades like 316 and 304.
| プロパティ | 310 Stainless Steel | 316ステンレス鋼 | 304ステンレススチール |
|---|---|---|---|
| 耐熱性 | Excellent (up to 2000°F / 1093°C) | Good (up to 1600°F / 871°C) | Fair (up to 1500°F / 816°C) |
| 耐腐食性 | Moderate, not suited for marine or chloride environments | Excellent in marine and chloride-rich environments | Good in general environments |
| Main Alloying Elements | High Cr (24–26%), Ni (19–22%) | Cr (16–18%), Ni (10–14%), Mo (2–3%) | Cr (18–20%), Ni (8–10.5%) |
| 作業性 | Moderate, needs stronger tools and force | Good, easy to form and weld | Excellent, widely used for forming and welding |
| 溶接性 | Good, but needs heat control | 素晴らしい | 素晴らしい |
| 料金 | Higher due to high alloy content | ミディアム | より低い |
| Best Use Cases | High-temperature furnaces, kilns, heat exchangers | Marine parts, chemical processing, medical devices | General-purpose equipment, sinks, appliances |
結論
310 stainless steel is a high-temperature, corrosion-resistant alloy designed for demanding environments. Its high chromium and nickel content give it excellent strength and oxidation resistance at temperatures up to 2000°F. It performs well in furnaces, heat exchangers, kilns, and petrochemical equipment.
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