Overview
Alloy 347 (UNS S34700) is columbium stabilized austenitic stainless steel plate with good general corrosion resistance and somewhat better resistance in strong oxidizing conditions than 321 (UNS S32100). It has excellent resistance to intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range of 800 – 1500°F (427 – 816°C). The alloy has good oxidation resistance and creep strength to 1500°F (816°C). It also possesses good low temperature toughness.
Due to the stabilizing element Nb, its resistance to intergranular corrosion and polysulfuric acid intergranular stress corrosion is good. Its corrosion resistance in acid, alkali, salt and other corrosive media is similar to that of Ti-containing 18-8 austenitic stainless steel. Therefore, it is widely used in boiler, power generation, petroleum, chemical, synthetic fiber, food, paper and other industries. Used in large boiler superheater tubes, reheater tubes, steam pipelines and petrochemical heat exchangers.
Specification
ASTM A213/A213M-21a Standard Specification for Seamless Ferritic and Austenitic Alloy-Steel Boiler, Superheater, and Heat-Exchanger Tubes.
| Specifications | ASTM A213 / ASME SA213 |
| Dimensions | ASTM, ASME and API |
| Range | 1/2"OD - 12"OD |
| Outside Diameter | 3.00 mm - 219.10 mm, 6.35 mm O.D to 114.3 mm O.D |
| Length | Single Random, Double Random & Required Length |
| Thickness | 0.40 mm - 12.70 mm, 0.8 mm to12.7 mm |
| Schedule | SCH20, SCH30, SCH40, STD, SCH80, XS, SCH60, SCH120, SCH140, SCH160, XXS |
| Type | Seamless |
| Form | Round Tube, Square Tube, Rectangular Tube |
| End | Plain End, Beveled End, Treaded |
ASTM A213 SS 347 Equivalent
Grade | UNS No | Old British | Euronorm | Swedish SS | Japanese JIS | ||
| BS | En | No | Name | ||||
| 347 | S34700 | 347S31 | 58G | 1.4550 | X6CrNiNb18-10 | 2338 | SUS 347 |
Chemical Composition
| Grade | C | Mn | Si | P | S | Cr | Cb | Ni | Fe |
| SS 347 | 0.08 max | 2.0 max | 1.0 max | 0.045 max | 0.030 max | 17.00 - 20.00 | 10xC – 1.10 | 9.00 - 13.00 | 62.74 min |
Mechanical Properties
UNS No | Grade | Proof Stress | Tensile Strength | Elongation | Hardness Max | |
| HB | HRB | |||||
| S34700 | 347 | 205 | 515 | 40 | 201 | 92 |
Physical Properties
| Properties | Metric | Imperial |
| Density | 7.7 – 8.03 g/cm3 | 0.278 – 0.290 lb/in³ |
Applications
- 1. Aerospace.
- 2. Laboratory benches & equipment.
- 3. Coastal architectural panelling, railings & trim.
- 4. Boat fittings.
- 5. Chemical Processing.
- 6. Heat Exchangers.
- 7. Woven or welded screens for mining, quarrying & water filtration.
- 8. Threaded fasteners.
- 9. Springs.
