Great Steel & Metals offers high quality stainless steel 309 sheet/plates to all its customers across the world that is appreciated for the applications with elevated temperature. It offers comparable resistance to corrosion, excellent oxidation resistance and retention of large fraction of strength at room temperature a compared to the common austenitic alloy 304 on account of high content of nickel and chromium present in it.

General Properties

In the applications where high temperature corrosion resistance is required, alloy 309 (UNS S30900) is extensively used. Under the non-cyclic conditioners, oxidation up to 1900°F is resisted by the alloy.

The alloy 309 contain high content of chromium and low content of nickel on account of which it could be used in the atmosphere containing sulfur at up to 1832°F. The alloy offers moderate resistance to absorption of carbon and therefore is not recommended highly carburizing atmospheres.

The alloy is subject to sigma phase precipitation when it is heated between 1202-1742°F. A degree of toughness is restores by the solution annealing treatment at 2012-2102°F.

Applications

• Furnaces — burners, doors, fans, piping and recuperators
• Fluidized Bed Furnaces — grids, piping, wind boxes
• Paper Mill Equipment
• Petroleum Refining — catalytic recovery systems, recuperators
• Power Generation — pulverized coal burners, tube hangers
• Thermal Processing — annealing covers and boxes, burners grids, doors, fans, lead pans and neutral salt pots, muffles and retorts, recuperators, walking beams
• Waste Treatment — incinerators, rotary kilns and calciners

Standards

ASTM……..A 240
ASME……..SA 240
AMS……….5523

Corrosion Resistance

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.

Creep Properties

Typical Creep Properties

Chemical Analysis

Weight % (all values are maximum unless a range is otherwise indicated)

Physical Properties

Density
0.285 lbs/in3
7.89 g/cm3

Specific Heat
0.12 BTU/lb-°F (32 – 212°F)
502 J/kg-°K (0 – 100°C)

Modulus of Elasticity
28.5 x 106 psi
193 GPa

Thermal Conductivity 212°F (100°C)
9.0 BTU/hr/ft2/ft/°F
15.6 W/m-°K

Melting Range
2500 – 2590°F
1480 – 1530°C

Electrical Resistivity
30.7 Microhm-in at 68°C
78 Microhm-cm at 20°C

Mechanical Properties

Typical Values at 68°F (20°C)

Fabrication Data

Alloy 309 can be easily welded and processed by standard shop fabrication practices.

Hot Forming
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.

Cold Forming
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.

Welding
Alloy 309 can be readily welded by most standard processes including TIG, PLASMA, MIG, SMAW, SAW and FCAW.