S275NL
EN 10025-3 · 1.0491
S275NL is a structural steel (Fine Grain Normalised family) to EN 10025-3 (1.0491). It has a specified 0.2 % proof stress of 275 MPa and a typical tensile strength of about 370 MPa, with a uniform elongation of 24 %. 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 401 MPa above it. Fine-grain processing delivers good low-temperature toughness alongside the quoted strength.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 24.0% · conservative analysis limit ½εu = 12.0%
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 10025-3 for this grade — confirm exact limits (thickness-dependent) against the standard.
Available forms
Common applications
- Building and bridge steelwork
- Platforms, frames and support structures
- Crane and lifting structures
- General heavy fabrication
History
The fine-grain normalised structural steels were developed to push yield strength up while keeping the low-temperature toughness and weldability that plain C-Mn steel loses as it is strengthened — achieved by normalising a micro-alloyed (Nb/V) fine grain. EN 10025-3 is the weldable fine-grain family. The number, 275, is the minimum yield strength in MPa. This is a low-temperature (…L) quality.
- 1960Normalised micro-alloyed steels bring fine-grain toughness to higher strengths
- 1990EN 10113 / EN 10025-3 standardise the S…N / NL normalised grades
- 2004EN 10025-3:2004 — current form
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.