EN 10028-3 — Flat products made of steels for pressure purposes. Part 3: Weldable fine grain steels, normalized
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Scope
Normalized fine-grain pressure-vessel plate in strength classes 275, 355, 400 and 460 MPa: P275N/NH/NL1/NL2, P355N/NH/NL1/NL2, P460N/NH/NL1/NL2 (and P275NH etc.). Al-killed with Nb/V/Ti grain refinement; impact guaranteed at −20 °C (N/NH), −40 °C (NL1) and −50 °C (NL2); NH grades have elevated-temperature yield to 400 °C.
Grades covered by EN 10028-3
| Grade | No. | Type | C % | Yield MPa | Tensile MPa | Nearest equivalents |
|---|---|---|---|---|---|---|
| P355NH | 1.0565 | Weldable fine-grain normalized steel for pressure purposes, elevated temperature | ≤ 0.2 | 355 | 490–630 | A516 Gr. 70, A537 Cl. 1, A737 Gr. B |
Revision history and superseded standards
| Year | Change |
|---|---|
| 1992 | EN 10028-3:1992 — replaced DIN 17102 |
| 2003 | Revision |
| 2009 | Revision; PED alignment |
| 2017 | EN 10028-3:2017 — current |
Supersedes: DIN 17102:1983 (StE, WStE, TStE, EStE 255–500); BS 1501-224/225; EN 10028-3:1992 / 2003 / 2009.
Where to buy the standard
The full text is copyrighted by CEN and is not reproduced here. Purchase the current edition from CEN or your national standards body. The values on this site are the normative limits as published; the standard's own tables, notes and test methods govern.
Related standards
Normalised fine grain, for the cold end
Where part 2 of EN 10028 publishes strength at elevated temperature, part 3 covers weldable fine-grain steels in the normalised condition for the opposite duty: pressure equipment that must stay tough as the temperature falls. P275NH, P355NH, P460NH and their L1 and L2 variants sit here.
The suffix states the impact requirement. NH is tested to −20 °C, NL1 to −40 °C and NL2 to −50 °C. The strength tables are nearly identical across the three — what is being bought is certified toughness at a stated temperature, not additional load capacity.
Where fine grain comes from, and why it matters
The toughness comes from grain size, and the grain size comes from aluminium, niobium, vanadium or titanium additions combined with a controlled normalising treatment. Fine grain raises yield strength and lowers the ductile-to-brittle transition temperature at the same time — one of the few metallurgical levers that improves two properties at once.
It also survives post-weld heat treatment, which is why these grades dominate in vessels that will be stress-relieved. The trade-off is that normalising is part of the product: a plate of the same chemistry supplied as-rolled is not the same material and will not carry the certificate.