
Alloy 309 (UNS S30900) is an austenitic stainless steel developed for use in high temperature corrosion resistance applications. The alloy resists oxidation up to 1900°F (1038°C) under non-cyclic conditions. Frequent thermal cycling reduces oxidation resistance to approximately 1850°F (1010°C).
Because of its high chromium and low nickel content, Alloy 309 can be utilized in sulfur containing atmospheres up to 1832°F (1000°C). The alloy is not recommended for use in highly carburizing atmospheres since it exhibits only moderate resistance to carbon absorption. Alloy 309 can be utilized in slightly oxidizing, nitriding, cementing and thermal cycling applications, albeit, the maximum service temperature must be reduced.
When heated between 1202 – 1742°F (650 – 950°C) the alloy is subject to sigma phase precipitation. A solution annealing treatment at 2012 – 2102°F (1100 – 1150°C) will restore a degree of toughness.
309S (UNS S30908) is the low carbon version of the alloy. It is utilized for ease of fabrication. 309H (UNS S30909) is a high carbon modification developed for enhanced creep resistance. It most instances the grain size and carbon content of the plate can meet both the 309S and 309H requirements.
Alloy 309 can be easily welded and processed by standard shop fabrication practices.
ASTM........A 240
ASME........SA 240
AMS..........5523
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.
Typical Creep Properties
Temperature | Creep Strain (MPa) | Creep Rapture (MPa) | |||||
---|---|---|---|---|---|---|---|
°C | °F | 1000 H | 10000 H | 100000 H | 1000 H | 10000 H | 100000 H |
600 | 1112 | 120 | 80 | 40 | 190 | 120 | 65 |
700 | 1292 | 50 | 25 | 20 | 75 | 36 | 16 |
800 | 1472 | 20 | 10 | 8 | 35 | 18 | 7.5 |
900 | 1652 | 8 | 4 | 3 | 15 | 8.5 | 3 |
1000 | 1832 | 4 | 2.5 | 1.5 | 8 | 4 | 1.5 |
Weight % (all values are maximum unless a range is otherwise indicated)
Element | 309 | 309S | 309H |
---|---|---|---|
Chromium | 22.0 min.-24.0 max. | 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. | 12.0 min.-15.0 max. |
Carbon | 0.20 | 0.08 | 0.04 min.-0.10 max. |
Manganese | 2.00 | 2.00 | 2.00 |
Phosphorus | 0.045 | 0.045 | 0.045 |
Sulfer | 0.030 | 0.030 | 0.030 |
Silicon | 0.75 | 0.75 | 0.75 |
Iron | Balance | Balance | Balance |
Typical Values at 68°F (20°C)
Yield Strength 0.2% Offset | Ultimate Tensile Strength | Elongation in 2 in. | Hardness | ||
---|---|---|---|---|---|
psi (min.) | (MPa) | psi (min.) | (MPa) | % (min.) | (max.) |
45,000 | 310 | 85,000 | 586 | 50 | 202 (HBN) |
Alloy 309 can be easily welded and processed by standard shop fabrication practices.
Heat uniformly at 1742 – 2192°F (950 – 1200°C). After hot forming a final anneal at 1832 – 2101°F (1000 – 1150°C) followed by rapid quenching is recommended.
The alloy is quite ductile and forms in a manner very similar to 316. Cold forming of pieces with long-term exposure to high temperatures is not recommended since the alloy is subject to carbide precipitation and sigma phase precipitants.
Alloy 309 can be readily welded by most standard processes including TIG, PLASMA, MIG, SMAW, SAW and FCAW.
JIANGSU MITTEL STEEL INDUSTRIAL LIMITED
Jiangsu Mittel Steel Industrial Limited is located in Wuxi City, a beautiful city near Shanghai. Wuxi is close to Shanghai (BAO STEEL) ,Zhangjiagang (ZPSS),Ningbo (BAO XIN),KUN SHAN (DKSS), enjoy excellent geographic location and convenient water, land and air transportation. , Wuxi become the biggest stainless steel sheet ,plate and coil supply Centers in China. Jiangsu Mittel Steel Industrial Limited was established in 1998 years. as one of the largest stockists and manufacturers of industrial grade Stainless Steel products and derivatives in Wuxi ,We keep a stock of 50000 tons every month, so we can delivery goods in fast time.
Our company supplies cold/hot-rolled stainless steel
sheets,stainless steel coils and stainless steel Plate to many
steel factories from athome and abroad, including Shanxi Taigang
Iron& Steel CO, . Ltd (TISCO)Zhangjiagang Pohang (ZPSS),
Shanghai BAO STEEL, Ningbo Baoxin and steel factories in Taiwan
area, Mainland Chinese and foreign countries and regions.
Our long-term business lines are
201.202.304(1.4301).304L.316.316L(1.4404).430.409L, 309S
,310S(1.4845).317L.904L.S31803(1.4462).S32750.S32760, Finish: 2B,
BA, NO. 1 NO. 4, HL, 8K and so on...Meanwhile, our company is also
engaged in the long-term supply of homemade & imported medium
and thick plates, galvanized and carbon steel products.
Adhering to the principle of "quality first and customer
foremost",our company will offer long-term service to nationwide
manufacturers of household appliances, elevators, tableware,
ornaments, tanks and machines. We can offer precise frosted
wiredrawing, 8K mirror finishing and skim board oil-abrasion of
various specifications at any time. The precisely-processed
products will meet your requirements for high quality. Our company
is a modern enterprise integrating distribution and storage.
If you are interested in any of our products or would like to
discuss a custom order, please feel free to contact us. We are
looking forward to forming successful business relationships with
new clients around the world in the near future.