S275JR vs S355JR: differences explained
S275 vs S355: 275 against 355 MPa minimum yield, the same EN 10025-2 family and delivery condition, a 29 % strength gap that rarely changes the section but often changes the price and the weld procedure.
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Overview
S275 and S355 are neighbours, not opposites. Both are hot-rolled non-alloy structural steels to EN 10025-2, both come as JR, J0 or J2, both weld with the same consumables and both arrive from the same mills. The whole difference is 80 MPa of yield strength and the chemistry needed to reach it.
That matters less than the S235 versus S355 question, because a 29 per cent strength gain is often eaten by deflection or buckling limits before it saves any steel. Where it does count is in plate work and in markets where S275 has quietly stopped being stocked — in much of Europe a mill will happily roll S355 and charge almost the same, which is why the grade is disappearing from service-centre lists.
S275JR vs S355JR side by side
| Property | S275JR | S355JR |
|---|---|---|
| Standard | EN 10025-2:2019 | EN 10025-2:2019 |
| Material number | 1.0044 | 1.0045 |
| Old names | St44-2, Fe430B, 43B | St52-3, Fe510B, 50B |
| Min. yield ReH, ≤ 16 mm | 275 MPa (40 ksi) | 355 MPa (51 ksi) |
| Min. yield, 16–40 mm | 265 MPa | 345 MPa |
| Min. yield, 40–63 mm | 255 MPa | 335 MPa |
| Min. yield, 63–80 mm | 245 MPa | 325 MPa |
| Tensile Rm, 3–100 mm | 410–560 MPa | 470–630 MPa |
| Elongation A, ≥ 3 mm | 23 % | 22 % |
| Impact energy, JR | 27 J at +20 °C | 27 J at +20 °C |
| Max C, ≤ 30 mm | 0.21 % | 0.24 % |
| Max Mn | 1.50 % | 1.60 % |
| Max P / S | 0.035 / 0.035 % | 0.035 / 0.035 % |
| Carbon equivalent CEV, ≤ 30 mm | 0.40 % | 0.45 % |
| Density, E modulus | 7.85 kg/dm³, 210 GPa | 7.85 kg/dm³, 210 GPa |
| Typical price difference | baseline | 0–4 % over S275 in Europe, sometimes zero |
| Stock availability (2026) | Falling: many service centres only order it in | Stocked in every form |
| ASTM closest | A572 Gr 42 / A283 Gr D | A572 Gr 50 |
| JIS closest | SM400B–SM490A | SM490A / SS490 |
| GB closest | Q275 | Q345B |
Which should you choose?
Default to S355JR unless the drawing or the local stock says otherwise. The strength is 29 % higher, the price difference in Europe has narrowed to almost nothing, and the availability is better. S275JR still makes sense where an existing structure is built in it and connection details must match, where a design is deflection-governed and the extra yield buys nothing, or where a market genuinely prices it lower — which is still the case in parts of Asia and the Middle East.
- Extending or repairing a structure already framed in S275, where the connection design assumes that yield
- Deflection-governed floor beams: stiffness is set by the E modulus, which is identical in both grades
- Slender compression members where buckling, not yield, decides the section
- Heavy cold forming, where the lower carbon equivalent gives more forgiving bend radii
- Markets where S275 is genuinely cheaper and available from stock
- Any new design where strength governs — the section drops one or two sizes
- Plate work, machine frames and crane girders, where thickness costs money per tonne
- Structures under EN 1090 EXC2 and above, where S355 is what fabricators are set up for
- Export projects: S355 is the grade an inspector and a third-party reviewer expect to see
- Anywhere the two grades cost the same — which in Europe is most of the time
Frequently asked questions
What is the difference between S275 and S355?
Minimum yield strength: 275 MPa against 355 MPa up to 16 mm thickness, and 410–560 against 470–630 MPa tensile. Everything else — standard, delivery condition, weldability, density, modulus — is effectively the same.
Can I substitute S355 for S275?
Structurally almost always yes, since every strength property is higher. But it is still a design change: the engineer has to confirm that no detail relies on the lower yield, such as a ductile connection designed to yield before a weld fails.
Is S275 cheaper than S355?
Rarely by much in Europe today. Mills roll far more S355, so the scale advantage has closed the gap; in some months S275 costs more because it has to be ordered specially.
Do S275 and S355 weld the same way?
Broadly yes, with the same consumables. S355 allows a higher carbon equivalent (0.45 against 0.40 per cent), so above roughly 30 mm it is more likely to need preheat. Check the actual CEV on the mill certificate rather than the maximum in the standard.
What is S275JR in ASTM?
The nearest common equivalents are A572 Grade 42 and A283 Grade D. None is identical: the chemistry limits and the impact testing regime differ, so a substitution needs the designer's approval.
Which is better for a steel building frame?
S355 in most cases. Columns and beams sized on strength get lighter, and the material cost difference is small. Where the frame is governed by deflection or by the slenderness of long members, the extra yield does nothing and S275 is equally good.
Related comparisons
Verified against EN 10025-2:2019. Last checked: September 2026.