347H Stainless Steel
347H is a niobium stabilized austenitic stainless steel for high temperature corrosive service. Niobium improves resistance to intergranular corrosion, with the source listing strong performance from 450℃ to 850℃ and better intergranular corrosion resistance than 304 stainless steel. Its creep and stress rupture properties at elevated temperature are also described as better than 304/304L, with a maximum service temperature of 850℃. In solution treated condition, the cross section can be reduced by 80% during cold forming. The source advises matching 347 filler for welding and avoiding chloride environments.
Product details
Chemical composition
| 347H | C | Si | Mn | P | S | Cr | Ni | Nb |
|---|---|---|---|---|---|---|---|---|
| min | 0.04 | – | – | – | – | 17 | 9 | 0.32 |
| max | 0.1 | 1 | 2 | 0.045 | 0.03 | 19 | 13 | 1.1 |
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Grade equivalents
| English Item | UNS | W.Nr. | JIS | GB/T | Other Grades |
|---|---|---|---|---|---|
| 347H | S34709 | 1.4912 | SUS347H | 07Cr18Ni11Nb 1Cr19Ni11Nb S34779 | X7CrNiNb18-10 4912-347-09-I Z2CND17-11 Z2CND18-13 Z8CNNb18-10 |
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Physical properties
| Density g/cm³ | 7.78 |
|---|---|
| Melting range ℃ | 1398-1427 |
| Thermal conductivity (100℃) λ/(W/m•℃) | 16.2-17.9 |
| Specific heat J/kg•℃ | 460-500 |
| Elastic modulus GPa | 195-200 |
| Electrical resistivity μΩ•m | 0.78-0.98 |
| Linear expansion coefficient a/10-6℃-1 | 16.5-18.0 |
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Mechanical properties
| Tensile strength Rm N/mm | ≥515~540 |
|---|---|
| Yield strength RP0.2 N/mm | ≥205 |
| Elongation % | ≥35~40 |
| Hardness HB | ≤187~192 |
| *After solution heat treatment | |
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Applications
- Boiler systems in supercritical thermal power units
- High-temperature molten-salt storage tanks for concentrated solar power
- High-temperature petrochemical reaction equipment
- Equipment for photovoltaic polysilicon production
- Industrial boilers and pressure vessels
Available product forms
- Round Bar
- Wire
- Forgings
- Plate
- Strip
- Seamless Pipe
- Welded Pipe
- Capillary Tube
- Flanges
- Pipe Fittings
- Non-standard Custom Parts
Values follow the Milike materials catalogue and are provided for preliminary review. Confirm the applicable purchase specification, heat treatment condition, and inspection requirements before final material selection.
- Heat and batch traceability
- PMI testing available
- Cut-to-size processing
- Material certificates on request
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