Overview
ASTM A213 Grade 309 (UNS S30900) steel tube is an austenitic stainless steel which developed for using in high temperature corrosion resistance applications. It resists oxidation up to 1900°F (1038°C) under non-cyclic conditions. Frequent thermal cycling reduces oxidation resistance to approximately 1850°F (1010°C).
Because of its high chromium and low nickel content, Grade 309 can be utilized in sulfur containing atmospheres up to 1832°F (1000°C). It's not recommended for use in highly carburizing atmospheres since it exhibits only moderate resistance to carbon absorption. Grade 309 can be utilized in slightly oxidizing, nitriding, cementing and thermal cycling applications, albeit, the maximum service temperature must be reduced. When heated between 1202 – 1742°F (650 – 950°C) the alloy is subject to sigma phase precipitation. A solution annealing treatment at 2012 – 2102°F (1100 – 1150°C) will restore a degree of toughness.
Specification
ASTM A213/A213M-21a Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes.
Chemical Composition
| Element | 309 | 309S | 309H |
|---|---|---|---|
| Chromium | 22.0 min.-24.0 max. | 22.0 min.-24.0 max. | 22.0 min.-24.0 max. |
| Nickel | 12.0 min.-15.0 max. | 12.0 min.-15.0 max. | 12.0 min.-15.0 max. |
| Carbon | 0.20 | 0.08 | 0.04 min.-0.10 max. |
| Manganese | 2.00 | 2.00 | 2.00 |
| Phosphorus | 0.045 | 0.045 | 0.045 |
| Sulfer | 0.030 | 0.030 | 0.030 |
| Silicon | 0.75 | 0.75 | 0.75 |
| Iron | Balance | Balance | Balance |
Mechanical Properties
| 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 |
Physical Properties
| Properties | Metric | Imperial |
|---|---|---|
| Density | 8 g/cm3 | 0.289 lb/in³ |
| Melting point | 1455°C | 2650°F |
Tolerances of ASTM A213 TP309 Heat Exchanger Tube
| Specification | Size OD Range Inches | Tolerances | |||
|---|---|---|---|---|---|
| O.D. | Wall | ||||
| Plus | Minus | Plus | Minus | ||
| ASTM-A-213 | Under 1.000 | .004" | .004" | 20% | 0% |
| ASME-SA-213 | 1.000 to 1.500 | .006" | .005" | 20% | 0% |
| Cold Finished Seamless | 1.501 to 1.999 | .008" | .008" | 22% | 0% |
| Heat Exchanger Tube | 2.000 to 2.499 | .010" | .010" | 22% | 0% |
| Minimum Wall | 2.500 to 2.999 | .012" | .012" | 22% | 0% |
| 3.000 to 4.000 | .015" | .015" | 22% | 0% | |
| 4.001 to 5.000 | .015" | .025" | 22% | 0% | |
