S235JR vs S235J0: differences explained
S235JR vs S235J0: identical strength, identical chemistry limits in most respects, one difference that matters — the temperature at which 27 joules of impact energy is proven, +20 °C against 0 °C.
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Overview
Same steel, different promise about cold. Both grades sit in EN 10025-2 with a 235 MPa minimum yield and the same tensile range; what changes is the Charpy V-notch test. JR is verified at room temperature, J0 at zero, J2 at minus twenty. The steel is not magically tougher — the mill simply commits to a result at a lower temperature, and to the cleaner chemistry needed to pass it consistently.
That is why the upgrade is cheap in thin material and expensive in thick. A 10 mm plate will pass at 0 °C almost regardless; a 60 mm plate needs controlled rolling, tighter phosphorus and sulphur and sometimes a normalising pass.
S235JR vs S235J0 side by side
| Property | S235JR | S235J0 |
|---|---|---|
| Standard | EN 10025-2:2019 | EN 10025-2:2019 |
| Material number | 1.0038 | 1.0114 |
| Impact energy | 27 J at +20 °C | 27 J at 0 °C |
| Min. yield ReH, ≤ 16 mm | 235 MPa | 235 MPa |
| Tensile Rm, 3–100 mm | 360–510 MPa | 360–510 MPa |
| Elongation A, ≥ 3 mm | 26 % | 26 % |
| Max C, ≤ 16 mm | 0.17 % | 0.17 % |
| Max P | 0.035 % | 0.030 % |
| Max S | 0.035 % | 0.030 % |
| Max N | 0.012 % | 0.012 % |
| Deoxidation | Optional (FN — rimming not permitted) | FN, fully killed practice in effect |
| Typical thickness limit in stock | All sections and plate | Plate and heavier sections |
| Price difference | Baseline | 0–3 % in thin, 3–8 % in heavy plate |
| Where it is required | Indoor, ambient, non-critical | Outdoor structures in temperate climates |
| Old name | St37-2 | St37-3 U |
| Next step up | S235J2 (27 J at −20 °C) | S235J2 (27 J at −20 °C) |
| ASTM parallel | A36 (no low-temperature requirement) | A36 with supplementary impact testing |
| EN 1993-1-10 use | Limited thickness in cold service | Greater permitted thickness at low temperature |
| Certificate | EN 10204 3.1 with room-temperature Charpy | EN 10204 3.1 with 0 °C Charpy |
| Same weld procedure? | Yes | Yes |
Which should you choose?
Specify J0 when the steel will be cold and loaded at the same time — outdoor frames in a temperate climate, plant that starts up in winter, thick welded joints where restraint adds to the risk. JR is enough indoors and for light thicknesses. If the structure is genuinely exposed to hard winters, do not stop at J0: EN 1993-1-10 usually pushes the answer to S235J2 or S355J2, and the cost gap between J0 and J2 is smaller than the gap from JR to J0.
- Interior structures, plant rooms and equipment frames that stay above freezing
- Thin material where fracture toughness is not the governing check
- Non-welded or lightly welded parts — brackets, trims, covers
- Where availability decides: JR is the grade every stockist holds in every form
- Cost-sensitive general fabrication with no low-temperature clause in the specification
- Outdoor structures in a climate that reaches 0 °C
- Thicker welded plate, where restraint and thickness both reduce effective toughness
- When EN 1993-1-10 gives a permitted thickness that JR cannot meet
- Projects whose specification names an impact class — read it before ordering
- Structures with dynamic or impact loading, where a brittle start is the failure mode to avoid
Frequently asked questions
What does J0 mean in S235J0?
The impact quality: a Charpy V-notch test giving at least 27 joules at 0 °C. JR is the same energy at +20 °C, J2 at −20 °C.
Is S235J0 stronger than S235JR?
No. Yield, tensile and elongation are identical. Only the guaranteed low-temperature toughness differs, along with slightly tighter phosphorus and sulphur limits.
Can I use S235J0 where S235JR is specified?
Yes — it meets everything JR requires and adds a toughness guarantee. The reverse is not true and should never be accepted without the designer's approval.
Does J0 cost more?
Slightly in thin material, more in heavy plate, where reaching 27 J at 0 °C requires controlled rolling and cleaner steel. In sections the difference is often lost in the rounding.
Which impact class do I actually need?
EN 1993-1-10 answers it from the service temperature, the plate thickness and the stress level. As a rough guide: indoors JR, outdoors in a temperate climate J0, outdoors in a cold climate or in thick welded joints J2.
Is S235J0 the same as St37-3?
It replaced St37-3 U from the withdrawn DIN 17100. The old name still appears on drawings in Germany, Türkiye and the Balkans.
Related comparisons
Verified against EN 10025-2:2019. Last checked: October 2026.