Stainless Steel - Grade 309
Grade 309 is a highly alloyed austenitic stainless steel used for its excellent oxidation resistance, high temperature strength and creep resistance. The lower nickel content of SX309 improves resistance to sulphur attack at high temperatures. It is tough and ductile, and can be readily fabricated and machined.
Grade 309 is a highly alloyed austenitic stainless steel used for its excellent oxidation resistance, high temperature strength and creep resistance. The lower nickel content of SX309 improves resistance to sulphur attack at high temperatures. It is tough and ductile, and can be readily fabricated and machined.
Sheet Thickness: 0.05mm and above
Typical Applications Grade 309/309S is used exclusively for its high temperature oxidation resistance. It is common for Grade 309, 310 and 321 to be used in the same piece of equipment in the various temperature regions.
Chemical Composition (ASTM A240)
C | Mn | P | S | Si | Cr | Ni | |
309 309S | 0.20 max 0.08 max | 2.00 max | 0.045 max | 0.030 max | 1.00 max | 22.0 - 24.0 | 12.0 - 15.0 |
Typical Properties in the Annealed Condition
The properties quoted in this publication are typical of mill production and unless indicated should not be regarded as guaranteed minimum values for specification purposes.
Mechanical Properties at Room Temperature
Grade 309 | Grade 309S | |||
TYPICAL | MIN | TYPICAL | MIN | |
Tensile Stength MPa | 560 | 515 | 540 | 515 |
Proof Stress (0.2% Offset) MPa | 285 | 205 | 280 | 205 |
Elongation (Percent in 50 mm) | 54 | 40 | 54 | 40 |
Hardness (Brinell) | 164 | 159 | ||
Endurance (fatigue) limit MPa | 260 | 260 | ||
Properties at Elevated Temperatures
Short Time Elevated Temperature Tensile Stress
Short Time Elevated Temperature Tensile Stress
Temperature | oC | 550 | 650 | 750 | 850 | 950 | 1 050 |
Tensile Stress | MPa | 440 | 360 | 240 | 150 | 70 | 30 |
Creep Rupture Stress
Time | Temperature ℃ | 600 | 700 | 800 | 900 | 1 000 |
1 000 h 10 000 h 100 000 h | Stress MPa Stress MPa Stress MPa | 180 150 100 | 90 50 40 | 35 30 20 | 20 10 5 | 5 2 - |
Thermal Processing
1. Annealing. Heat between 1 050℃ and 1 150℃ and water quench. This treatment ensures that all carbides are in solution.
2. Stress Relieving 250-400℃ for 1 hour.
3. Hot Working
Initial forging and pressure 1150-1 200℃
Finishing temperature 1000℃
Note: Soaking times to ensure uniformity of temperature are up to 12 times that required for mild and carbon steels.
2. Stress Relieving 250-400℃ for 1 hour.
3. Hot Working
Initial forging and pressure 1150-1 200℃
Finishing temperature 1000℃
Note: Soaking times to ensure uniformity of temperature are up to 12 times that required for mild and carbon steels.
