ThePipingMart Blog Grades AISI – SAE 309 Stainless Steel (UNS S30900) – Composition, Properties, and Uses

AISI – SAE 309 Stainless Steel (UNS S30900) – Composition, Properties, and Uses

AISI 309 Stainless Steel

For those in the metalworking industry, AISI 309 is a common alloy with many useful properties. This steel has a higher corrosion resistance than 304 stainless steel but lower than 310 and 316 stainless steel, making it ideal for many industrial applications. Read on to learn more about the properties and uses of this versatile alloy.

What Forms is AISI – SAE 309 Stainless Steel Available at Piping Mart?

  • AISI – SAE 309 Stainless Steel Nuts
  • AISI – SAE 309 Stainless Steel Fasteners
  • AISI – SAE 309 Stainless Steel Channels
  • AISI – SAE 309 Stainless Steel Bolts
  • AISI – SAE 309 Stainless Steel Tubing
  • AISI – SAE 309 Stainless Steel Pipe Fittings

AISI – SAE 309 Stainless Steel Composition

SS 309 is used for various applications due to its high chromium and nickel content. This type of alloy has excellent corrosion resistance properties and offers superior resistance to scaling even in environments that reach temperatures up to 2000°F. It also has enhanced durability, making it suitable for Inconel sheet production. The composition of AISI 309 stainless steel includes 25-27% chromium, 14-17% nickel, 2% manganese, .2%-.5% silicon, 0-1.5% molybdenum, .75%-1.25% titanium and minor amounts of phosphorus, sulfur, nitrogen, and carbon. This specific alloy can also be used as a universal steel substitute where improved temperature creep deformation resistance is desired compared to other common austenitic alloys.

Element Content (%)
Iron, Fe 60
Chromium, Cr 23
Nickel, Ni 14
Manganese, Mn 2
Silicon, Si 1
Carbon, C 0.20
Phosphorous, P 0.045
Sulfur, S 0.030

AISI – SAE 309 Stainless Steel Properties

AISI stainless steel 309 is an austenitic chromium-nickel stainless steel that contains between 22% and 24% chromium, 12% to 15% nickel, and less than 0.2% carbon. This alloy is known for having excellent corrosion resistance and stress-corrosion cracking resistance, as well as high ductility, good formability, and impact strength at both room temperature and cryogenic temperatures. It also has good oxidation resistance up to 1125°F (600°C). However, due to its low carbon content, this alloy does not have good creep strength at elevated temperatures.

  • AISI 309 stainless steel is austenitic stainless steel that contains high levels of chromium and nickel.
  • The high chromium content gives the steel excellent corrosion resistance, while the high nickel content gives it good resistance to oxidation.
  • The steel has good mechanical properties, including high strength and good ductility.
  • AISI 309 stainless steel can be easily welded and formed, making it suitable for a wide range of applications.
  • The steel is non-magnetic and can be heat treated to achieve a variety of different microstructures.

AISI – SAE 309 Stainless Steel Physical Properties

309 SS is a strong, high-temperature-resistant metal. Its physical properties make it highly sought after in applications that require durability, such as Inconel sheeting. Its ability to resist corrosion and oxidation at temperatures exceeding 1000°F (537°C) makes it an ideal material for Inconel sheets, where temperature changes are frequent and intense. Its low carbon content helps minimize carbide precipitation during welding while its high nickel content increases resistance to corrosion and oxidation. AISI 309 Stainless Steel is also known for having excellent formability characteristics, making it easy to work with through a variety of processes. With superior chemical and mechanical properties, AISI 309 Stainless Steel is widely recognized for its value in industrial projects that require strength and durability—especially Inconel sheeting.

Properties Metric Imperial
Density 8 g/cm3 0.289 lb/in³
Melting point 1455°C 2650°F

AISI – SAE 309 Stainless Steel Mechanical Properties

AISI 309 is a versatile material with incredibly impressive mechanical properties. It is often used in Inconel sheet form and features a high chromium and nickel content. This combination results in resistance to corrosion and oxidation along with elevated levels of strength and hardness. In fact, this metal can handle temperatures up to 2200 degrees Fahrenheit without any significant loss in its mechanical properties across the board. AISI 309 stainless steel is often found in parts exposed to extreme heat or pressure where components must remain strong, durable, and resistant to fatigue damage from thermal cycling.

Properties Metric Imperial
Tensile strength 620 MPa 89900 psi
Yield strength (@ strain 0.200%) 310 MPa 45000 psi
Izod impact 120 – 165 J 88.5 – 122 ft-lb
Shear modulus (typical for steel) 77 GPa 11200 ksi
Elastic modulus 200 GPa 29008 ksi
Poisson’s ratio 0.27-0.30 0.27-0.30
Elongation at break (in 50 mm) 45% 45%
Hardness, Brinell 147 147
Hardness, Rockwell B 85 85
Hardness, Vickers (converted from Rockwell B hardness) 169 169

Thermal Properties

Properties Metric Imperial
Thermal expansion co-efficient (@ 0-100°C/32-212°F) 14.9 µm/m°C 8.28 µin/in°F
Thermal conductivity (@ 0-100°C/32-212°F) 15.6 W/mK 108 BTU in/hr.ft².°F

AISI – SAE 309 Equivalent

Other designations equivalent to 309 stainless steel are included in the following table.

ASTM A473 ASME SA403 ASTM A409 MIL-S-862
ASTM A479 ASME SA409 ASTM A511 SAE J405 (30309)
DIN 1.4828 ASTM A312 ASTM A554 SAE 30309

AISI – SAE 309 Stainless Steel Uses

Due to its high corrosion resistance, AISI 309 stainless steel is ideal for use in many industrial applications, such as chemical processing equipment, food processing equipment, heat exchangers, paper mills, power plants, textile equipment, oil refineries, and more. It can also be found in the automotive industry and is often used for exhaust systems due to its ability to withstand high temperatures without losing its form or strength. Additionally, this alloy can be used in architectural applications because it resists staining over time better than other alloys.

  • AISI 309 stainless steel is commonly used in welding applications.
  • AISI 309 stainless steel is often used in high-temperature applications.
  • AISI 309 stainless steel has good corrosion resistance.
  • AISI 309 stainless steel has good formability.
  • AISI 309 stainless steel is weldable by all standard fusion methods


Overall, 309 SS is an incredibly versatile metal that can be found in everything from automotive parts to kitchen appliances! Its combination of good formability and high corrosion resistance makes it perfect for any number of industrial or commercial applications. If you’re looking for an affordable yet reliable material that will stand up over time without losing its shape or integrity, then AISI 309 stainless steel could be just what you need! Thanks for reading—we hope this guide has been helpful in understanding the unique properties of this popular alloy!

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