Stainless steel AISI 309 belongs to high-alloyed alloys with increased heat resistance and corrosion resistance. This material has a long service life and excellent operational characteristics, allowing it to be widely used in the industrial sector - from mechanical engineering to oil refining.
The main characteristics and properties of AISI 309 alloy are as follows:
The designation of this alloy contains the letters AISI (an abbreviation for the American Institute of Metals and Alloys, where the standard was developed) and three digits. The first digit in the AISI 309 decryption indicates the material class, in this case - austenitic steel. The next two digits only indicate the serial number of the alloy in its category and do not have a direct relation to its chemical composition.
The technical characteristics of AISI 309 steel are as follows:
- Density: 7900 kg/cm³. This is a typical indicator for alloys of this category.
- Allowable stress at rupture deformation: 550 MPa, indicating the increased strength of the material.
- Yield strength: 230 MPa.
- Hardness according to the Brinell method: 217 units. This is a relatively high indicator among similar stainless steels in terms of composition.
| Standard |
ASTM A240 - Standard Specification for Chromium and Nickel-Chromium, Chromium and Manganese-Nickel Stainless Steels for Plates, Sheets, Strips, Pressure Vessels, and General Use ASTM A276 - Standard Specification for Finished Bars and Blooms, Unworked by the Hot or Cold Method, Other than Wrought (Secondary) Bars ASTM A403 - Standard Specification for Forged Austenitic Stainless Steel Pipe Fittings |
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| Classification | Stainless ferritic steel | ||||||
| Application | Rolled sheets, rolls, rails, pressure vessels | ||||||
Other names |
UNS | S30900 | |||||
| USA (ASTM A167) | Sheet rental | A167 309 | |||||
| USA (ASTM A240) | Flat rental | A240 Type 309 | |||||
| USA (ASTM A276) | Bars and profiles | A276 Type 309 | |||||
| USA (ASTM A403) | Fittings | A403 WP309 | |||||
| USA (ASTM A480) | Plates, sheets, strips | A480 309 | |||||
| USA (ASTM A473) | Stamps | A473 309 | |||||
| USA (ASTM A580) | Stainless wire | A580 Type 309 | |||||
The chemical composition of AISI 309 alloy mainly consists of chromium (from 19 to 21%) and nickel (from 11 to 13%), providing the material with high corrosion resistance and great heat resistance. Other chemical compounds such as nitrogen, sulfur, phosphorus, and carbon are present in very small quantities, less than 1%, and do not affect the alloy's properties or its technical indicators.
The steel is relatively easy to weld and does not require prior heat treatment or additional actions after welding. Additionally, it is well suited for both cold and hot forming. These qualities make the alloy a universal solution for the production of products of various shapes and configurations. Products made from this material can withstand long periods in high-temperature or aggressive environments, maintaining their strength and other technical characteristics.
Applications of AISI 309 and its analogs in various countries worldwide:
Due to its high heat resistance and resistance to various types of corrosion, the alloy is widely used in the industry. Products made from this material are used in mechanical engineering, oil refining, metallurgy, chemical, and mining industries. Various structural elements that operate at high temperatures without load or under weak load are made from its metal. Typical examples of practical applications of the alloy include furnace fittings, conveyor elements, cementation molds, as well as tanks and vessels operating under pressure at high temperatures in aggressive environments.
The Ukrainian analog of AISI 309 is the heat-resistant stainless alloy 20Х23Н13, which has a similar chemical composition and almost the same operational qualities and technical characteristics. In Japan, the equivalent of this alloy is the SUS309 grade, and in Germany, it is X12CrNi23-13. In the domestic market, the alloy is represented by various types of rolled products - round, rectangular, square bars, and sheets.
Chemical composition in % of steel 309
| C | Mn | P | S | Si | Cr | N | No | Fe |
| <0.2 | <2.0 | <0.045 | <0.015 | 1.5-2.5 | 19.0-21.0 | <0.11 | 11.0-13.0 | Rest |
Mechanical properties of material 309
| Strength limit (temporary breaking strength), min., MPa | 550 |
| Yield strength, 0.2%, MPa | 230 |
| Rockwell hardness, HRB max. | 95 |
| Brinell hardness, HB type. | 217 |
| Magnetic properties | Minimal |
| Relative elongation, min., % | 30 |
Characteristics at elevated temperatures
| Temperature, °C | 600 | 700 | 800 | 900 |
| Yield strength, MPa | 80 | 25 | 10 | 4 |
| Temperature, °C | 600 | 700 | 800 | 900 |
| Strength limit, MPa | 120 | 36 | 18 | 8.5 |
| Strength limit, MPab | 65 | 16 | 7.5 | 3 |