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Stainless Steel 309, 309S

Stainless steels are high­alloy steels which have higher corrosion resistance compared to other steels due to the presence of large amounts of chromium. Based on their crystalline structure, they are further divided into ferritic, austenitic, and martensitic steels.

Grade 309 stainless steel has high corrosion resistance and strength compared to 304 stainless steel.

The following datasheet gives an overview of grade 309 stainless steel.

Forms available

Stainless 309 and 309S are available from stock as Pipe.

Machinability

Grade 309 stainless steel can be machined similar to that of 304 stainless steel.

Welding

Grade 309 stainless steel can be welded using fusion or resistance welding methods. Oxyacetylene welding method is not preferred for welding this alloy.

Hot Working

Grade 309 stainless steel is hot worked at 1177°C (2150°F) followed by reheating at 982°C (1800°F). It can be then quenched rapidly. Post­work annealing can be done to restore its corrosion resistance property.

Cold Working

Grade 309 stainless steel can be headed, upset, drawn, and stamped even though it has high work hardening rate. Annealing is performed after cold working in order to reduce internal stress.

Annealing

Grade 309 stainless steel is annealed at 1038­1121°C (1900­2050°F) followed by quenching in water.

Hardening

Grade 309 stainless steel does not react to heat treatment. Strength and hardness of this alloy can be increased by cold working.

Applications

Grade 309 stainless steel is used in the following applications:

  • Boiler baffles
  • Furnace components
  • Oven linings
  • Fire box sheets
  • Other high temperature containers.

Chemical Composition

Iron 60.00
Chromium 23.00
Nickel 14.00
Manganese  2.00
Silicon  1.00
Carbon  0.20
Phosphorous  0.045
Sulphur 0.030

Mechanical Properties

Typical Tensile Strength  620 MPa
Typical Yield Strength  310 MPa
Typical Elongation  45%

Machinability

Machining of grade 309S stainless steel is similar to that of grade 304.

Welding

Grade 309S stainless steel can be welded using most of the resistance and fusion methods. Oxyacetylene welding is not preferred for this steel.

Hot Working

Hot working of grade 309S stainless steel can be done at 1177°C (2150°F) and reheated at 982°C (1800°F). This process is followed by rapid cooling to obtain maximum corrosion resistance.

Cold Working

Grade 309S stainless steel can be drawn, headed, upset and stamped, although this steel has high work hardening rate. However, it has be fully annealed after cold­working to reduce internal stress.

 Annealing

Grade 309S stainless steel can be annealed at temperature ranging from 1038 to 1121°C (1900 to 2050°F) and then quenched with water.

Hardening

Grade 309S stainless steel is unresponsive to heat treatment. The hardness and strength of the steel can be increased through cold working.

Applications

The following are the major applications of grade 309S stainless steel:

  • Oven linings
  • Boiler baffles
  • Fire box sheets
  • Furnace components
  • Other high temperature containers.

Chemical Composition

   %
Iron 60.00
Chromium 23.00
Nickel 14.00
Manganese  2.00
Silicon  1.00
Carbon 0.20
Phosphorus 0.045
Sulphur  0.030

Mechanical Properties

Ultimate Tensile Strength MPa 620
2% Yield Strength MPa  310
Elongation %  45

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