The EN 10025-2 ladder: S235JR (235 MPa) for light framing and furniture tube, S275JR (275 MPa) for mid-duty frames and purlins, S355JR (355 MPa) for columns, beams and heavy structures. Price steps run roughly $10–20 per grade — and upgrading the grade often lets you drop a section size, which can cost less overall.
Every structural quotation starts with one letter-number pair. S235, S275 or S355 — the number is the minimum yield strength in MPa, and the choice ripples through section size, weight and price. This is the plain-language ladder, and the arithmetic that should drive it.
The Ladder at a Glance
| Grade | Min Yield (≤16 mm) | Tensile (MPa) | Impact (JR) | Typical Duty |
|---|---|---|---|---|
| S235JR | 235 MPa | 360–510 | 27 J @ +20 °C | Light framing, furniture tube, fencing, mezzanine joists |
| S275JR | 275 MPa | 430–580 | 27 J @ +20 °C | Mid-duty frames, purlins, equipment supports |
| S355JR | 355 MPa | 470–630 | 27 J @ +20 °C | Columns, rafters, bridges, crane structures |
Charpy grades move with service temperature: JR (+20 °C) → J0 (0 °C) → J2 (−20 °C). Cold-climate projects step down the alphabet, not up the number.
The Money Question: Grade vs Section Size
Steel prices step roughly $10–20 per ton per grade level. But a stronger grade carries more load per kilogram — so sometimes S355 in a smaller section beats S235 in a bigger one:
| Scenario | Option A | Option B | Winner |
|---|---|---|---|
| Fence posts, 2 m span | S235 60×60×3 tube | S355 60×60×3 tube | S235 — strength not the limit |
| Rafter, 12 m span, 1.2 t load | S235 IPE 400 (66.3 kg/m) | S355 IPE 330 (49.1 kg/m) | S355 — 26% lighter offsets the grade premium |
| Column, 6 m, heavy axial | S275 HEB 240 | S355 HEB 220 | Check deflection — often S355 wins on weight |
Deflection and stability still govern many members — the engineer signs off the final call.
What Buyers Get Wrong
- Upgrading "to be safe" without checking connections — a smaller S355 section changes bolt layouts and plate sizes.
- Ignoring availability: S235 tube and S355 beams are always in stock; S275 sits between and sometimes has the longest rolling lead time — we confirm per size.
- Confusing JR with the number: S355JR is not "more impact-resistant" than S235JR — both test at +20 °C. Cold service needs J0/J2 suffixes.
Grade comparisons: S355JR vs Q355B vs A572 Gr50 · S355JR deep dive · GB equivalents
Not sure which grade wins on cost?
Send the loads or the drawing to [email protected] or WhatsApp +86 191 5745 8011 — we price both options per section so the trade-off is visible. MOQ 5 t, all grades from stock or rolling.
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