309/309S Stainless Steel is an austenitic heat-resisting stainless steel grade, 309/309S Stainless Steel is suitable for a number of high-temperature applications due to its high chromium and nickel content. Alloys 309 and 309S are austenitic chromium-nickel stainless steels that are often used for higher-temperature applications. Due to their high chromium and nickel content, Alloys 309 and 309S are highly corrosion resistant, have outstanding oxidation resistance, and excellent heat resistance while providing good strength at room and elevated temperatures.
309/309S Stainless Steel Features
- Austenitic Heat resistant alloys, high chromium and nickel content
- Excellent corrosion resistance
- More resistant to marine atmospheres than Alloy 304
- Outstanding oxidation resistance at higher temperatures, oxidation resistant to 1900°F
- Moderate strength at high temperature
- Ease of fabrication
- Good sulfidation resistance
- Good weldability
309/309S Stainless Steel Chemical Composition
The only significant difference between 309 and 309S is the carbon content. Alloy 309S has a much less carbon composition (0.08% max) which minimizes carbide precipitation and improves weldability 309H has carbon content range from 0.04 to 0.10%. 309/309S Stainless Steel is a chromium-nickel stainless grade, 22-24% chromium, with Min. 12% Nickel content, this gives Alloy 309/309S good corrosion resistance at elevated temperatures.
| C | Mn | Si | P | S | Cr | Ni | Fe | |
|---|---|---|---|---|---|---|---|---|
| 309 | 0.20 Max | 2.0 Max | 0.75 Max | 0.045 Max | 0.03 Max | Min: 22.0 Max: 24.0 | Min: 12.0 Max: 15.0 | Balance |
| 309S | 0.08 Max | 2.0 Max | 0.75 Max | 0.045 Max | 0.03 Max | Min: 22.0 Max: 24.0 | Min: 12.0 Max: 15.0 | Balance |
| 309H | Min: 0.04 Max: 0.10 | 2.0 Max | 0.75 Max | 0.045 Max | 0.03 Max | Min: 22.0 Max: 24.0 | Min: 12.0 Max: 15.0 | Balance |
309/309S Stainless Steel Mechanical Properties
| Grade | Tensile Strength Mpa(Min) | Yield Strength 0.2% Mpa (Min) | Elongation % | Hardness (Brinell) MAX |
|---|---|---|---|---|
| 309/H | 515 | 205 | 40 | 217 |
309/309S Stainless Steel Physical Properties
| Density Lbm/In^3 | Thermal Conductivity (BTU/H Ft. °F) | Electrical Resistivity (In X 10^-6) | Modulus Of Elasticity (Psi X 10^6) | Coefficient Of Thermal Expansion (In/In)/ °F X 10^-6 | Specific Heat (BTU/Lb/ °F) | Melting Range (°F) |
|---|---|---|---|---|---|---|
| At 68°F: 0.285 | 9.0 At 32- 212°F | 30.7 At 68°F | 28.5 | 8.28 At 32 – 212°F | 0.1200 At 68°F To 212°F | 2500-2590 |
309S Stainless Steel Equivalent
- UNS S30908
- JIS SUS309S
- GOST 20KH23N13
- EN X12CrNi23-13
Forms
Corrosion Resistance
Alloy 309 is not designed for service in wet corrosive environments. The high carbon content, which is present to enhance creep properties, has a detrimental effect on aqueous corrosion resistance. The alloy is prone to intergranular corrosion after long-term exposure to high temperatures. However, due to its high chromium content (23%), Alloy 309 is more corrosion-resistant than most heat-resistant alloys.
High-Temperature Corrosion Alloy 309 resists high-temperature corrosion in most in-service conditions.
Alloy 309 resists high-temperature corrosion in most in-service conditions. Operating temperatures are as follows:
- Oxidizing conditions (max. sulfur content–2 g/m3)
- 1922°F (1050°C) continuous service
- 2012°F (1100°C) peak temperature
- Oxidizing conditions (max. sulfur greater than 2 g/m3)
- 1742°F (950°C) maximum temperature
- Low oxygen atmosphere (max. sulfur content–2 g/m3)
- 1832°F (1000°C) maximum temperature
- Nitriding or carburizing atmospheres
- 1562–1742°F (850–950°C) maximum
The alloy does not perform as well as Alloy 600 (UNS N06600) or Alloy 800 (UNS N08800) in reducing, nitriding, or carburizing atmospheres, but it does outperform most heat-resistant stainless steels in these conditions.
Oxidation Resistance
Type 309/309S is a high-temperature chromium-nickel austenitic stainless steel that resists oxidation at temperatures up to 1900˚F in dry air at constant temperature. Under thermal cycling conditions, this grade resists oxidation up to a temperature of approximately 1850˚F. Type 309 has good sulfidation resistance but low resistance to carburization and should not be used in highly carburizing atmospheres.
309 has only moderate resistance to carbon absorption and is not suggested for use in highly carburizing atmospheres.
Type 309 is non-magnetic in the annealed and cold-worked conditions and is as resistant to corrosion as Type 304/304L.
Welding
306/309S have good or very good weldability, a filler material with a matching composition should preferably be used to ensure weld metal properties (e.g. strength, corrosion resistance) equivalent to those of the parent metal.
Grade 309 stainless steel can be welded using fusion or resistance welding methods. The oxyacetylene welding method is not preferred for welding this alloy.
Hot Working
Grade 309 stainless steel is hot worked at 1177°C (2150°F) followed by reheating at 982°C (1800°F). It can be then quenched rapidly. Post-work annealing can be done to restore its corrosion resistance property.
Cold Working
Grade 309 stainless steel can be headed, upset, drawn, and stamped even though it has a high work hardening rate. Annealing is performed after cold working to reduce internal stress.
Heat Treatment
Grade 309 stainless steel is annealed at 1038-1121°C (1900-2050°F) followed by quenching in water.
309 stainless steel does not react to heat treatment, 309 can only be hardened by cold working.
Applications
Alloys 309 and 309S are used exclusively for their high-temperature oxidation resistance, excellent high-temperature strength, along with their resistance to creep deformation and environmental attack. Some examples include, but are not limited to:
- Annealing covers and boxes
- Carbon saggers
- Waste incinerators
- Pulverized coal burners
- Brazing fixtures
- Lead pans, neutral salt pots
- Muffles, retorts
- Furnace fans and shafts
- Radiant tubes for aluminum and steel annealing
- Glass forming equipment
- Thermowells
- Paper mill equipment
- Power boiler tube hangers
- Rotary kilns and calciners
- Anchor bolts
309S/309H And 1.4833 Comparison
| Standard | Grade | C | Mn | Cr | Ni | N |
|---|---|---|---|---|---|---|
| ASME II A SA-240 | TYPE 309S | ≤0.08 | ≤2.00 | 22.0-24.0 | 12.0-15.0 | |
| ASTM A240 | TYPE 309H | 0.04-0.10 | ≤2.00 | 22.0-24.0 | 12.0-15.0 | |
| ASTM A240 | TYPE 309S | ≤0.08 | ≤2.00 | 22.0-24.0 | 12.0-15.0 | |
| EN 10095 | 1.4833 | ≤0.15 | ≤2.00 | 22.00-24.00 | 12.00-14.00 | ≤0.11 |