1. Standard Classification
BS EN 10025 is the British adoption of the European standard for hot-rolled structural steels, covering six parts:
Part 2: General structural steels (S275/S355)
Part 3: Normalized/normalized-rolled weldable fine grain steels
Part 4: Thermomechanical rolled weldable fine grain steels
Part 5: Weathering steels
Part 6: Quenched & tempered high-yield steels
Chemical Composition (Typical %)
| Element | S275JR | S355JR | Limits |
|---|---|---|---|
| C (max) | 0.21 | 0.22 | EN 10025-2 |
| Si (max) | 0.40 | 0.55 | |
| Mn (max) | 1.50 | 1.60 | |
| P (max) | 0.035 | 0.035 | |
| S (max) | 0.035 | 0.035 | |
| CEV (max) | 0.40 | 0.45 | Pcm formula |
Key Differences Between S275 & S355
| Parameter | S275 | S355 |
|---|---|---|
| Yield Strength | 275 MPa | 355 MPa (↑29%) |
| Tensile Strength | 410-560 MPa | 470-630 MPa |
| Weight Savings | - | Up to 20% lighter for same load |
| Weldability (CEV) | Better (0.40 max) | Good (0.45 max) |
| Cost | Lower | Higher (~15-20% premium) |
