347H
Data verified347H is the high-carbon niobium-stabilised grade for creep-range pressure service, combining the sensitisation resistance of 347 with code creep-rupture values. It is widely used in refinery and steam plant.
Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.04–0.10 |
| Si | ≤0.75 |
| Mn | ≤2.00 |
| P | ≤0.045 |
| S | ≤0.030 |
| Cr | 17.00–19.00 |
| Ni | 9.00–13.00 |
| Nb | 8×C–1.00 |
Weight percent, per the governing standard ranges. Actual values per heat are on the mill certificate.
Properties
| Delivery condition | Annealed |
| Hardness | ≤217 HB (annealed) |
| Tensile strength | 515–690 MPa |
| Density | 7.90 g/cm³ |
| Creep service | Rated for pressure service above ~525 °C |
Heat treatment
Solution anneal 1040–1120 °C, rapid cool, with grain size controlled for creep performance.
Equivalent grades
| Standard | Designation |
|---|---|
| din | 1.4912 |
| aisi | 347H |
| jis | SUS347 |
| gb | 07Cr19Ni11Nb |
Compare side by side: 347H vs 347 · 347H vs 321H
Equivalents overlap in chemistry and use but are not always identical — see our equivalents guide before substituting in certified designs.
Applications & Processing
Applications: Refinery and petrochemical pressure piping, steam headers, superheater tubes, catalyst regenerator parts.
Processing: Welds with 347-type fillers; post-weld heat treatment is generally not required for stabilised grades in this service.
Need 347H from stock?
Steel.Wiki is sponsored by Shenzhen NewAsia Special Steel (Nasteel), a special-steel stockholder in Shenzhen stocking mold, tool and alloy steels with EN 10204 3.1 certification.
Ask for a quotationVisit NasteelSource: ASTM A240 / A312 published ranges · Last updated 2026-11-03. Data is indicative — verify critical values against the governing standard and mill certificate before use.