309S Stainless Steel Plate

309S stainless steel is a highly alloyed austenitic stainless steel used for its excellent oxidation resistance, high-temperature strength, and creep resistance. The lower nickel content of Stainless Steel 309, compared to Stainless Steel 310, improves its resistance to hydrogen sulfide (H2S) attack at high temperatures. It is tough and ductile and can be readily fabricated and machined. SS 309S is the low-carbon version, and is recommended for applications where sensitization and subsequent corrosion by high temperature gases or condensates during shutdown may pose a problem. Stainless Steel 309S is used for its high-temperature oxidation resistance and/or resistance to H2S attack for applications such as furnace parts, firebox sheets, high-temperature containers, catalytic converters, and exhaust systems.

Excellent oxidation resistance
    High temperature strength
    High creep resistance
    Tough and dectile
    Readily fabricated and machined
    Resistant to hydrogen sulfide attack at high temperatures

Common Applications 
    Furnace parts
    Muffles, Retorts
    Firebox sheets
    High temperature containers
    Catalytic converters
    Exhaust systems
    Radiant Tubes
    Fluidized bed coal combusters
    Petroleum refineries and steam boilers
    Thermowells
    Carbon Saggers
    Paper Mill Equipment
    Power boiler tube hangers
    Anchor bolts
    Gladd forming equipment
    Food processing industry

Corrosion resistance

Types 309 and 309S provide excellent general corrosion resistance. They are more resistant to marine

atmospheres than Type 304. They exhibit high resistance to sulfite liquors and are useful for handling 
nitric acid, nitric-sulfuric acid mixtures, and acetic, citric, and lactic acids.
These materials are generally considered heat-resisting alloys. Their destructive scaling temperature 
is about 2000 °F (1093 °C). They exhibit good scaling resistance in both continuous and intermittent 
service, but the alloys should not be used above 1800 °F (982 °C) for intermittent service.

Formability
Types 309 and 309S stainless steels can be roll formed, stamped and drawn readily. In process annealing 
is sometimes required to reduce hardness and restore ductility. Type 309 is extremely stable and will 
remain nonmagnetic when cold worked. Its lower elongation makes this grade somewhat more difficult 
to form than other 300 series austenitic grades.

Weldability
The austenitic class of stainless steels is generally considered to be weldable by the common fusion and 
resistance techniques. Special consideration is required to compensate for a higher coefficient of thermal 
expansion to avoid warping and distortion. Type 309 is generally considered to have weldability.

Heattreatment
These alloys are not hardenable by heat treatment. 

Annealing: Anneal at 1900 – 2050 °F (1038 – 1121 °C), then water quench or rapidly air cool.