S275JR
EN 10025-2 · 1.0044
S275JR is a structural steel (Carbon-Manganese family) to EN 10025-2 (1.0044). It has a specified 0.2 % proof stress of 275 MPa and a typical tensile strength of about 430 MPa, with a uniform elongation of 23 %. Nominal carbon content is around 0.21 %. For nonlinear FEA, a bilinear model uses E = 210 GPa up to yield and a tangent modulus of 684 MPa above it. A plain-carbon steel: economical and predictable, strengthened by carbon content and heat treatment rather than alloying.
Bilinear material model — nonlinear FEA
Uniform elongation εu = 23.0% · conservative analysis limit ½εu = 11.5%
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
Very good — low carbon equivalent, weldable by all processes with preheat only for thick or highly restrained joints.
Formabilitygood
Good cold forming; slightly less than S235 but ample for normal bending and rolling.
Machinabilitymoderate
Machines a little better than S235 thanks to marginally higher carbon; still not free-cutting.
Corrosion resistancepoor
None inherent — protect by paint or galvanising in exposed use.
Hardenabilitylow
Not a hardening steel; supplied as-rolled or normalised.
Toughnessmoderate
JR = 27 J at +20 °C. Choose J0/J2 for cold or fatigue-critical duty.
Expert notes
S275 is the middle child of the structural range. For decades (as Grade 43 / St 44) it was the standard structural steel; today S355 has largely taken that role because the strength gain is nearly free, so you’ll often see S275 specified mainly to match existing structures or where deflection, not strength, governs.
Because deflection is set by stiffness (E), not yield, upgrading S275 to S355 buys you nothing on a serviceability-governed member — the section stays the same. Knowing whether a member is strength- or stiffness-limited tells you whether the grade even matters.
Same JR caveat as the rest of the family: +20 °C impact only. Specify J0/J2 for cold or dynamic duty.
It welds very well; preheat is only a concern in thick, restrained joints. A sound default when you want a bit more than mild steel without moving to S355.
Mechanical properties
| Condition | Section | Yield (MPa) |
|---|---|---|
| S275 · as-rolled | t ≤ 16 mm | 275 |
| 16 < t ≤ 40 mm | 265 | |
| 40 < t ≤ 63 mm | 255 | |
| 63 < t ≤ 80 mm | 245 | |
| 80 < t ≤ 100 mm | 235 | |
| 100 < t ≤ 150 mm | 225 |
UTS 410–560 MPa · Impact 27 J @ +20 °C · Hardness ~135 HB
Physical properties
| Density | 7850 | kg/m³ |
| Elastic modulus | 210 | GPa |
| Shear modulus | 81 | GPa |
| Poisson's ratio | 0.30 | |
| Thermal expansion | 12.0 | ×10⁻⁶/°C |
| Thermal conductivity | 52 | W/(m·K) |
| Specific heat | 470 | J/(kg·K) |
Chemical composition (wt %)
Available forms
Equivalent grades
| Standard | Grade | Note |
|---|---|---|
| BS 4360 | 43B | |
| ASTM | A529 Gr. 50 | Close; A572-42 is another near equivalent. |
| DIN 17100 | St 44-2 | |
| JIS | SM400B | |
| ISO 630 | E275B |
Historical designations
| Standard | Grade | Note |
|---|---|---|
| DIN 17100 | St 44-2 | “44” = ~440 MPa tensile. |
| BS 4360:1990 | 43B | UK Grade 43 — extremely common on legacy UK drawings. |
| Euronorm 25 | Fe 430 B | Pre-EN 10025 designation. |
Common applications
- General and structural steelwork
- Frames, platforms and support structures
- Baseplates and moderate-load connections
- Bridge secondary steel and general fabrication
- Plant and machinery frames
History
S275 succeeds the St 44 / Grade 43 steels — the mid-strength structural workhorse that sat between mild steel and the high-strength grades before S355 became the default.
- 1949DIN 17100 defines St 44-2
- 1968BS 4360 defines UK Grade 43 (43A/B/C/D)
- 1990EN 10025 introduces S275
- 2004EN 10025-2:2004 — current form of S275JR