S. S. 309 / 309S

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UNS - S30900 / S30908

Stainless Steel Grade 309 and 309S are austenitic chromium-nickel stainless steels that are frequently utilized for higher temperature applications. Because of their high chromium and nickel content, Alloys 309 and 309S are highly corrosion resistant, have greater resistance to oxidation, and magnificent heat resistance while giving good qualities at room and high temperatures.

The difference between Stainless Steel 309 and 309S is the carbon content. Alloy 309S has a substantially less carbon composition which reduces carbide precipitation and improves weldability.

  • Maximum temperature of 1000°C in service in the air
  • Very good resistance to carburizing
  • Good weldability and formability
  • Excellent resistance to corrosion and oxidation

  • Heating elements
  • Aircraft and jet engine parts
  • Heat exchangers
  • Carburizing annealing products
  • Sulphite liquor handling equipment
  • Kiln liners
  • Boiler baffles
  • Refinery and chemical processing equipment
  • Auto exhaust parts


This alloy machines same as type 304 stainless steel. The chips of this alloy are stringy and it will work harden very quickly. It is compulsory to keep the tool cutting at all times and utilize chip breakers.


By using fusion or resistance technique most of the austenitic stainless steels can be quickly welded. Oxyacetylene welding is not suggested. Filler metal should be AWS E/ER 309 or 309L.

Hot Working

Working temperatures of this alloy are 2150°F (1177°C), with reheating compulsory at 1800°F (982°C). Fast quenching is suggested. To reattain maximum corrosion resistance full post-work annealing is required.

Cold Working

In spite of the fact that this alloy has a high work hardening rate, this alloy can be drawn, headed, upset and stamped. To remove internal stress full annealing is required after cold work.


1900-2050°F (1038-1121°C), water quench.


These alloys do not respond to heat treatment. Cold work will cause an increase in both hardness and strength.

Chemical Composition

309 0.20 max1.0 max 0.045 max0.030 max22.0 - 24.02.0 max12.0 - 15.0 Remainder
309S 0.08 max1.0 max 0.045 max0.030 max22.0 - 24.02.0 max12.0 - 15.0Remainder

Mechanical Properties

GradeTensile Strength (ksi)0.2% Yield Strength (ksi)Elongation% in 2 inches

Physical Properties

309309STemperature in °C
Density7.9 g/cm³8.03 g/cm³Room
Specific Heat0.12 Kcal/kg.C0.12 Kcal/kg.C22°
Melting Range1399 - 1454 °C1399 - 1454 °C-
Modulus of Elasticity 200 KN/mm²200 KN/mm²22°
Electrical Resistivity78 µΩ.cm78 µΩ.cmRoom
Coefficient of Expansion14.9 µm/m °C14.9 µm/m °C20 - 100°
Thermal Conductivity15.6 W/m -°K15.6 W/m -°K20°

ASTM Specifications

Pipe / Tube (SMLS)Sheet / PlateBarForgingFitting
A 213, A 249 A 167 ,A 240A 276 A 473A 403


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