Views: 42 Author: Site Editor Publish Time: 2025-04-21 Origin: Site
309/309S stainless steel is an austenitic stainless steel with excellent high temperature oxidation resistance and corrosion resistance, and is widely used in high temperature environments. This steel contains a high proportion of chromium (22-24%) and nickel (12-15%), which enables it to maintain good strength and oxidation resistance at temperatures up to 1000°C. 309S is a low-carbon version of 309 stainless steel with a lower carbon content (≤0.08%), better welding performance, and effectively reduces the risk of intergranular corrosion during welding. 309/309S stainless steel is commonly used in industrial furnace components, heat treatment equipment, chemical heat exchangers and other structural materials in high temperature corrosive environments.
We specialize in selling all kinds of stainless steel pipe fittings, steel pipes, steel plates, flanges, bolts and nuts. Our products are widely used in many fields, from precision machinery manufacturing to warm home decoration and even high-end aerospace industry. With excellent product quality and wide application adaptability, we have become a trusted choice for many industries. We can not only provide a variety of products, but also provide customized processing services according to the specific needs of customers, ensuring that every cooperation can accurately meet your expectations. With advanced production equipment and strict quality management system, we are committed to providing high-quality pipeline solutions to customers around the world. Welcome to contact us.
Wet Corrosion
Alloy 309 is not designed for service in wet corrosive environments. The high carbon content, which is present to enhance creep properties, has a detrimental effect on aqueous corrosion resistance. The alloy is prone to intergranular corrosion after long term exposure at high temperatures. However, due to its high chromium content (23%), Alloy 309 is more corrosion resistant than most heat resistant alloys.
High Temperature Corrosion
Alloy 309 resists high temperature corrosion in most in-service conditions. Operating temperatures are as follows:
Oxidizing conditions (max. sulfur content–2 g/m3)
1922°F (1050°C) continuous service
2012°F (1100°C) peak temperature
Oxidizing conditions (max. sulfur greater than 2 g/m3)
1742°F (950°C) maximum temperature
Low oxygen atmosphere (max. sulfur content–2 g/m3)
1832°F (1000°C) maximum temperature
Nitriding or carburizing atmospheres
1562–1742°F (850–950°C) maximum
The alloy does not perform as well as Alloy 600 (UNS N06600) or Alloy 800 (UNS N08800) in reducing, nitriding or carburizing atmospheres, but it does outperform most heat resistant stainless steels in these conditions.
Element | 309 | 309S |
Chromium | 22.0 min.-24.0 max. | 22.0 min.-24.0 max. |
Nickel | 12.0 min.-15.0 max. | 12.0 min.-15.0 max. |
Carbon | 0.2 | 0.08 |
Manganese | 2 | 2 |
Phosphorus | 0.045 | 0.045 |
Sulfer | 0.03 | 0.03 |
Silicon | 0.75 | 0.75 |
Iron | Balance | Balance |
Properties | Metric | Imperial |
Tensile strength, ultimate | 620 MPa | 89900 psi |
Tensile strength, yield (0.2%) | 310 MPa | 45000 psi |
Izod impact | 120 - 165 J | 88.5 - 122 ft-lb |
Modulus of elasticity | 200 GPa | 29000 ksi |
Shear modulus | 77 GPa | 11200 ksi |
Poissons ratio | 0.3 | 0.3 |
Elongation at break (in 50 mm) | 45% | 45% |
Hardness, Brinell (converted from Rockwell B hardness) | 147 | 147 |
Hardness, Knoop (converted from Rockwell B hardness) | 164 | 164 |
Hardness, Rockwell B | 85 | 85 |
Hardness, Vickers (converted from Rockwell B hardness) | 169 | 169 |
Standard | Equivalent Grade | Notes |
UNS | S30900 | Unified Numbering System (USA) |
ASTM / ASME | A240 / A312/ A213 309 | Plates, pipes, tubes |
EN / DIN | X15CrNiSi20-12 (1.4828) | European standard |
JIS (Japan) | SUS 309 | Japanese Industrial Standard |
BS (UK) | 309S24 | British Standard |
ISO | 309 | Matches AISI 309 |
AFNOR (France) | Z 15 CNS 20.12 | French standard |
GOST (Russia) | 12Ch18N10 (approx.) | Closest Russian grade |
Property | 309 | 304 |
Nickel (Ni) | 12.0–15.0% | 8.0–10.5% |
Chromium (Cr) | 22.0–24.0% | 18.0–20.0% |
Carbon (C) | ≤0.20% (309) / ≤0.08% (309S) | ≤0.08% (304) / ≤0.03% (304L) |
High-Temp Resistance | Excellent – up to ~1000–1100°C | Good – up to ~870°C |
Corrosion Resistance | Very good, especially in oxidizing environments | Excellent for general use |
Weldability | Good (better in 309S) | Excellent |
Cost | Higher | More economical |
Main Use | High-temp environments: furnaces, kilns, heat exchangers | General-purpose: kitchenware, tanks, architecture |
Heat Resistance:
309 wins — it’s designed for elevated temperature applications and resists oxidation up to 1100°C.
304 is not suitable for continuous use above ~870°C.
Corrosion Resistance:
Both are strong, but 309 is superior in harsh, hot oxidizing atmospheres.
Cost & Availability:
304 is cheaper and more widely used, making it the go-to for most standard stainless steel applications.
Hot Working
Forging temperature: The material should be heated to a temperature between 1175°C to 1260°C (2150°F to 2300°F). It should be hot worked above 982°C (1800°F) to avoid cracking and deformation.
Post-hot working: Air cooling or rapid quenching is recommended to avoid grain growth and ensure proper microstructure.
Cold Working
Cold working methods such as stamping, drawing, and cold rolling can be applied to 309 stainless steel, but the material will harden more quickly than other austenitic steels due to its higher chromium and nickel content.
Work hardening occurs rapidly, increasing the strength and hardness of the material. Intermediate annealing may be required for extensive cold working operations.
Welding
GTAW (Gas Tungsten Arc Welding) or TIG (Tungsten Inert Gas): This method provides precise heat control and is excellent for producing high-quality welds with good corrosion resistance and aesthetic appearance, especially on thinner materials. Argon is typically used as the shielding gas.
GMAW (Gas Metal Arc Welding) or MIG (Metal Inert Gas): A faster process suitable for thicker sections and longer welds. It generally requires less operator skill than SMAW (Shielded Metal Arc Welding) or Stick Welding: A versatile and portable method, often used for thicker materials and in outdoor environments. It uses coated electrodes that provide their own shielding. E309 or E310 electrodes are typically used.
SAW (Submerged Arc Welding): Used for welding thick sections, providing high deposition rates and good penetration.
Furnace Components: Linings, burners, doors, fans, piping, and recuperators.
Boiler Components: Baffles and other parts exposed to high heat.
Oven Linings and Components: For industrial and commercial ovens.
Heat Exchangers: Especially in high-temperature environments.
Kiln Linings: In ceramic, glass, and other high-temperature kilns.
Petrochemical Equipment: In chemical processes involving high heat and corrosive gases.
Power Generation: Components in thermal power plants and solar energy systems.
Aerospace: Engine components and combustion systems.
Thermal Processing: Annealing covers and boxes, lead pans, and neutral salt pots.
Waste Treatment: Incinerators and rotary kilns.
-Pipe and Tube (EN 10216-5, ASTM A213, ASTM A249, A312, A790,)
-Forged Fitting and Flange (ASTM A182 , ASTM A105,ASTM B564 )
-Butt Weld Fittings (ASTM A234, ASTM A403,ASTM A815)
-Round bar , Billet (ASTM A276, ASTM A479)
- Plate, Sheet, Strip(ASTM A240, EN 10028-7, A480)
-Bolting, Nuts（ASTM A193, A194, A320）
We Export 309/309S stainless steel to Saudi Arabia, United Arab Emirates, Qatar, Bahrain, Oman, Kuwait, Turkey, Egypt, Yemen , Syria, Jordan, Cyprus, Singapore, Malaysia, Indonesia, Thailand, Vietnam, South Korea, Japan, Sri Lanka, Maldives, Bangladesh, Cambodia, Argentina, Bolivia, Brazil, Venezuela, Colombia, Ecuador, Guyana, Paraguay, Uruguay, United States Of America, Canada, Mexico, Panama, Jamaica, Bahamas, Denmark, Norway, Germany, France,Italy, United Kingdom, Spain, Belgium, Greece, Czech Republic, Portugal, Hungary, Albania, Austria, Finland, Ireland, Croatia, Malta, Nigeria, Algeria, Angola, South Africa, Libya, Egypt, Sudan, Europe, Africa, Asia, North America, South America, Middle East.etc
Is 309 stainless better than 304?
309 stainless steel is better than 304 in high-temperature and oxidizing environments due to its higher chromium and nickel content, which gives it superior heat resistance and oxidation resistance. However, 304 is more cost-effective and widely used for general corrosion resistance in lower-temperature settings. So, 309 is better for heat, while 304 is better for everyday corrosion and affordability.
What is the difference between 309 and 316 steel?
309 stainless steel is designed for high-temperature resistance, while 316 stainless steel excels in corrosion resistance, especially against chlorides (like saltwater). 309 has higher chromium and nickel, making it better for heat and oxidation, whereas 316 contains molybdenum, enhancing its resistance to pitting and chemical attack. So, use 309 for heat, and 316 for harsh chemical or marine environments.
