European Steel Chemical Composition — EN 10025-2 Limits for S235, S275, S355
Complete EN 10025-2:2019 chemical composition reference for European structural steels S235JR, S275JR, S355JR, S355J0, S355J2, and S355K2. Maximum carbon, silicon, manganese, phosphorus, and sulfur limits by product thickness, carbon equivalent value (CEV) formula per EN 1011-2, and practical weldability guidance for European steel designers.
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Carbon Equivalent Value (CEV) Formula
Per EN 1011-2, the carbon equivalent value for structural steels is:
CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15
For EN 10025-2 non-alloy structural steels, the simplified form applies since Cr, Mo, V, Ni, and Cu are typically at trace levels:
CEV ≈ C + Mn/6
The CEV is the primary indicator of weldability. Steels with CEV ≤ 0.45 generally require no preheat for thicknesses up to 30 mm under normal shop conditions per EN 1011-2.
Chemical Composition Limits by Grade
S235JR — EN 10025-2
| Element | t ≤ 16 mm | 16 < t ≤ 40 mm | 40 < t ≤ 100 mm | 100 < t ≤ 150 mm |
|---|---|---|---|---|
| C max | 0.17% | 0.17% | 0.20% | 0.20% |
| Si max | — | — | — | — |
| Mn max | 1.40% | 1.40% | 1.40% | 1.40% |
| P max | 0.025% | 0.025% | 0.025% | 0.025% |
| S max | 0.025% | 0.025% | 0.025% | 0.025% |
| N max | 0.012% | 0.012% | 0.012% | 0.012% |
| CEV max | 0.35% | 0.35% | 0.38% | 0.38% |
Note: S235JR has the lowest carbon content of the structural grades, giving excellent weldability. The CEV is typically 0.30-0.35 for standard rolling. No preheat is required for any thickness under normal conditions.
S275JR — EN 10025-2
| Element | t ≤ 16 mm | 16 < t ≤ 40 mm | 40 < t ≤ 100 mm | 100 < t ≤ 150 mm |
|---|---|---|---|---|
| C max | 0.18% | 0.18% | 0.20% | 0.22% |
| Si max | — | — | — | — |
| Mn max | 1.50% | 1.50% | 1.50% | 1.50% |
| P max | 0.025% | 0.025% | 0.025% | 0.025% |
| S max | 0.025% | 0.025% | 0.025% | 0.025% |
| N max | 0.012% | 0.012% | 0.012% | 0.012% |
| CEV max | 0.40% | 0.40% | 0.40% | 0.42% |
S275JR has slightly higher carbon and manganese than S235JR, giving increased strength while maintaining good weldability. CEV of 0.40 allows welding without preheat for thicknesses up to 40 mm.
S355JR — EN 10025-2
| Element | t ≤ 16 mm | 16 < t ≤ 40 mm | 40 < t ≤ 100 mm | 100 < t ≤ 150 mm |
|---|---|---|---|---|
| C max | 0.20% | 0.20% | 0.22% | 0.24% |
| Si max | 0.55% | 0.55% | 0.55% | 0.55% |
| Mn max | 1.60% | 1.60% | 1.60% | 1.70% |
| P max | 0.025% | 0.025% | 0.025% | 0.025% |
| S max | 0.025% | 0.025% | 0.025% | 0.025% |
| N max | 0.012% | 0.012% | 0.012% | 0.012% |
| CEV max | 0.42% | 0.42% | 0.43% | 0.45% |
S355JR has the highest carbon and manganese content of the standard structural grades. The CEV of 0.42-0.45 indicates that preheat may be necessary for thicknesses exceeding 40 mm, particularly in highly restrained joints.
S355J0, S355J2, and S355K2 — Impact Tested Variants
The J0, J2, and K2 suffixes indicate Charpy impact testing requirements (per EN 10025-2) but do not change the chemical composition. S355J0, S355J2, and S355K2 have identical chemical limits to S355JR at the same thickness range. The differences are:
| Suffix | Charpy Test Temp | Min CVN Energy | Application |
|---|---|---|---|
| JR | 20°C | 27 J | Interior, low-temperature risk |
| J0 | 0°C | 27 J | Exterior temperate climate |
| J2 | -20°C | 27 J | Cold climate, fracture-critical |
| K2 | -20°C | 40 J | Higher toughness, offshore/wind |
Weldability Guidelines per EN 1011-2
| Grade | CEV Range | Preheat Required | Electrode Type |
|---|---|---|---|
| S235JR | 0.30-0.35 | None (any thickness) | EN ISO 2560-A 42 |
| S275JR | 0.35-0.40 | None (t ≤ 40 mm), 50°C (t > 40 mm) | EN ISO 2560-A 42 |
| S355JR | 0.40-0.45 | 50°C (t > 30 mm), 100°C (t > 60 mm) | EN ISO 2560-A 46 |
| S355J2 | 0.41-0.45 | Same as S355JR | EN ISO 2560-A 46 |
| S355K2 | 0.42-0.47 | 75°C (t > 25 mm), 125°C (t > 50 mm) | EN ISO 2560-A 46/50 |
Preheat recommendations assume ambient temperature ≥ 5°C, low-hydrogen welding process (MAG/MIG or basic electrodes), and hydrogen levels HD ≤ 5 mL/100g. Increase preheat by 25-50°C for cellulosic electrodes or high-moisture conditions.
EN 10025-2 Sulphur and Phosphorus Limits
All structural grades per EN 10025-2 have a maximum of 0.025% phosphorus and 0.025% sulphur. For improved formability or lamellar tearing resistance, specify:
- S355N/NL — EN 10025-3 normalized weldable fine grain structural steels
- S355M/ML — EN 10025-4 thermomechanical rolled weldable fine grain structural steels
These fine-grain grades offer lower P and S limits (typically 0.020% max) and improved CEV control.
Frequently Asked Questions
What is the carbon equivalent value for S355JR steel?
S355JR has a CEV of 0.42-0.45 depending on thickness, calculated per EN 1011-2 as CEV = C + Mn/6 + (Cr + Mo + V)/5 + (Ni + Cu)/15. For thicknesses up to 40 mm, CEV max is 0.42. For 40-100 mm, CEV max is 0.43. For 100-150 mm, CEV max is 0.45.
Does S235JR require preheat before welding?
S235JR does not typically require preheat before welding at any thickness under normal shop conditions. The CEV of 0.30-0.35 is well below the 0.45 threshold where preheat becomes necessary per EN 1011-2. In cold weather (below 5°C) or highly restrained joints, a minimal 50°C preheat may still be advisable as good practice.
What is the difference between S355JR and S355J2 chemical composition?
S355JR and S355J2 have identical chemical composition limits per EN 10025-2 for the same thickness range. The difference is in Charpy impact testing: JR requires 27 J at 20°C, while J2 requires 27 J at -20°C. The actual measured chemistry may vary slightly between heats to achieve the lower-temperature toughness, but the guaranteed maximum limits per the standard are the same.
Related Pages
- European Steel Grades — Full EN 10025-2 grade property guide
- European Steel Properties — Complete fy/fu mechanical properties
- EN 1993 Beam Design — Flexural design per Eurocode 3
- European Base Plate Design — Column base plate per EN 1993-1-8
- All European References
Educational reference only. Chemical composition limits per EN 10025-2:2019. CEV per EN 1011-2:2001. Verify actual chemical composition against mill certificates and EN 10204 Type 3.1 inspection documents before welding. Results are PRELIMINARY — NOT FOR CONSTRUCTION without independent verification.
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