AISI 309S Stainless Steel Chemical Composition, Grade, Table and Document

The AISI 309S type of austenitic steel stands for its capability of working under high temperatures and has excellent resistance to corrosion in oxidizing environments. This alloy has chromium and nickel as its main constituents, which are usually found in 12% and 22% of the alloy in order to diminish the presence of carbon due to the fact that this tends to sensitize it and corrode faster at higher temperatures. AISI 309S has been engineered to handle situations of an increased temperature category for a long period of time like furnace equipment, heat exchangers, and automotive exhaust. This grade exhibits the highest oxidation resistance and thermal stability category and so it can safely be used in the chemical industry and other areas where good performance are required. Engineers and manufacturers work with charts and PDFs detailing chemical compositions and mechanical properties as well as the grades and fabrication techniques for their application, which is critical for optimal performance.

AISI 309S Austenitic Stainless Steel Chemical Composition And Grade Table

AISI 309S is an austenitic ferritic steel submitted the features associated with good high-temperature strength and corrosion resistance. Its chemical compositions generally include around 22% chromium and 12% nickel as well as low carbon content as a countermeasure of carbode precipitation at high temperatures. It provides higher oxidation resistance in both oxidizing and reducing environments that is compatible with its fuse part, heat exchanger connectors and high-temperature chemical processing machines. AISI 309S has excellent weldability and formability which makes it able to fill a variety of requirements where not only strength and corrosion resistance but also being resistant to elevated temperatures are important properties.

AISI 309S Austenitic Stainless Steel
Elements Fe Cr Ni Mn Si C P S
Min (%) 58.1 22 12 - - - - -
Max (%) 66 24 15 2.0 0.75 0.080 0.045 0.030

The Advantages and Disadvantages of AISI 309S Austenitic Stainless Steel


  • High Temperature Resistance: AISI 309S is characterized by the ability to resist high temperatures which make it suitable even for operations that are non-stop and always at high temperatures.

  • Oxidation Resistance: It rates strongly in both oxidation resistance and corrosion resistance, and in environments with elevated temperatures, it still remains durable and intact.

  • Corrosion Resistance: Due to the excellent feature of AISI 309S as regards corrosion resistance, minor corrosive environments do not pose a problem. As a result, the lifetime of the stainless-steel alloy is prolonged.

  • Weldability: The alloy grade of stainless steel has good weldability that ensures no difficulty in the fabrication and the joining parts of various applications.

  • Versatility: AISI 309S is widely used and highlighted in diverse applications such as furnaces, heat exchangers, and vehicle exhaust systems.


  • Sensitization: AISI 309S has the property of sensitization which causes intergranular corrosion in the some circumstances mostly when the material is exposed to high temperatures and for longer durations.

  • Limited Cold Formability: In contrast to some other austenitic stainless steels, AISI 309S shows weariness to cold workability, thus proper planning must be done during fabrication because of it.

  • Cost: In contrast to basic grades of stainless steels, AISI 309S may have an initial cost rate that is considered higher, which makes it less economical for specific applications.

  • Mechanical Properties at Room Temperature: The mechanical properties of this alloy appear to be better at room temperature as compared to other grades in Stainless Steel but the values may not be enough for certain structural uses.

  • Maintenance: Although AISI 309S demonstrates an impressive corrosion resistance, it can be subject to sensitization over time which could require maintenance and keep it par to its performance in challenging environments.

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