wilsonpipeline Stainless inventory now includes Alloy 309/309S (UNS S30900/S30908) in Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe,etc.
Overview
General Properties
Alloys 309 and 309S are austenitic chromium-nickel stainless steels that are often used for higher temperature applications. Due to their high chromium and nickel content, Alloys 309 and 309S are highly corrosion resistant, have outstanding resistance to oxidation, and excellent heat resistance while providing good strength at room and elevated temperatures. The only significant difference between 309 and 309S is the carbon content. Alloy 309S has a much less carbon composition which minimizes carbide precipitation and improves weldability.
Specifications: UNS S30900/S30908
Applications:
Alloys 309 and 309S are used exclusively for their high temperature oxidation resistance, excellent high temperature strength, along with their resistance to creep deformation and environmental attack. Some examples include, but are not limited to:
Heating elements
Aircraft and jet engine parts
Heat exchangers
Carburizing annealing products
Sulfite liquor handling equipment
Kiln liners
Boiler baffles
Refinery and chemical processing equipment
Auto exhaust parts
Standards:
ASTM/ASME: UNS S30900/S30908
EURONORM: FeMi35Cr20Cu4Mo2
DIN: 2.4660
Resistance
Corrosion Resistance
Provide excellent corrosion resistance
More resistant to marine atmospheres than Alloy 304
Often used at higher temperatures to take advantage of their oxidation resistance
Have high resistance to sulfite liquors
Generally considered heat resistant alloys
Destructive scaling temperature is approximately 2000oF
Good scaling resistance with regard to continuous and intermittent service
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.
Processing
Heat Treatment
Cannot be hardened through heat treatment because the consist solely of austenite at room temperature
Higher tensile and yield strengths that can be obtained through cold working and not followed by full annealing are not stable at the higher temperatures where these alloys are used
Creep properties can be negatively affected by the use of cold worked material at these higher temperatures
Fabrication
Can be roll formed, stamped, and drawn readily
In process annealing is often required to reduce hardness and increase ductility
Weldability
The austenitic class of stainless steels is generally considered to be weldable
Generally considered to have weldability equivalent to the most common alloys of the austenitic class 304 and 304L
Special consideration is needed to compensate for a higher coefficient of thermal expansion to avoid warping and distortion
Properties
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