P355NL1
EN 10028-3 · 1.0566
P355NL1 is a pressure-vessel steel (Fine Grain Normalised family) to EN 10028-3 (1.0566). It has a specified 0.2 % proof stress of 355 MPa and a typical tensile strength of about 490 MPa, with a uniform elongation of 22 %. Nominal carbon content is around 0.18 %. For nonlinear FEA, a bilinear model uses E = 210 GPa up to yield and a tangent modulus of 624 MPa above it. Fine-grain processing delivers good low-temperature toughness alongside the quoted strength.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 22.0% · conservative analysis limit ½εu = 11.0%
Bilinear (BISO) approximation. Elastic modulus E up to the 0.2% proof stress R_p0.2, then a single tangent slope Eₜ to the ultimate tensile strength: Eₜ = (Rₘ − R_p0.2) / (εu − R_p0.2/E − 0.002), where εu is the uniform elongation and Rₘ is a typical (nominal) UTS within the specified band. The half-εu figure is a conservative strain limit for the analysis. Treat these as guidance for first-pass models; for critical work use a measured true stress–strain curve for the actual product and condition.
Ratings — engineering judgement
Weldabilitygood
Low carbon (~0.18%) gives good weldability by all common processes; preheat rarely needed in thin sections.
Machinabilitymoderate
Soft and gummy at low carbon — sharp tooling helps surface finish.
Corrosion resistancepoor
No inherent corrosion resistance — protect by paint, galvanising or plating in exposed use.
Hardenabilitylow
Limited hardenability at low carbon — surface hardening is possible but through-hardening is not.
Toughnessgood
Fine-grain / alloy processing gives good low-temperature toughness for its strength.
Indicative ratings derived from composition and family — engineering guidance, not specification values.
Physical properties
| Density | 7850 | kg/m³ |
| Elastic modulus | 210 | GPa |
| Shear modulus | 80.8 | GPa |
| Poisson's ratio | 0.30 | |
| Thermal expansion | 12.0 | ×10⁻⁶/°C |
| Thermal conductivity | 48 | W/(m·K) |
| Specific heat | 470 | J/(kg·K) |
| Magnetic | Yes |
Typical values for fine grain normalised steel — use the mill certificate for the specific product.
Chemical composition (wt %)
Typical composition per EN 10028-3 — confirm exact limits against the standard.
Available forms
Common applications
- Boilers and pressure vessels
- Storage tanks and process drums
- Heat exchanger shells
- Piping components (to code)
History
The carbon-manganese pressure-vessel plates descend from the riveted-boiler steels of the steam age; EN 10028-2 (and ASME/ASTM in parallel) carry them as fully-killed, fine-grained weldable plate certified with guaranteed elevated-temperature proof strength. The number, 355, is the specified minimum yield strength in MPa.
- 1914Boiler codes formalise plate steel for pressure service (ASME Boiler Code, 1914–15)
- 1955DIN 17155 codifies the HI/HII boiler plates
- 1992EN 10028 harmonises European pressure-vessel plate
This profile is generated from the grade's core data and family. Composition is decoded from the designation where its naming system defines it; physical properties are family-typical and ratings are indicative. Confirm critical values against the governing standard or the mill certificate. Equivalents, historical designations and hand-written expert notes are added per grade over time.