S355JR and Q355B have nearly identical chemical compositions, ensuring consistent performance and fabrication:
| Element | S355JR (EN 10025-2) | Q355B (GB/T 1591) | Impact on Substitution |
|---|---|---|---|
| Carbon (C) | Max 0.24% | Max 0.24% | Identical limits ensure same weldability-both use E5015 electrodes without preheating. |
| Manganese (Mn) | 1.00–1.60% | 1.00–1.60% | Primary strengthener; identical ranges mean same yield/tensile strength. |
| Silicon (Si) | Max 0.55% | 0.15–0.40% | S355JR's higher max has no effect-both deoxidize effectively, avoiding voids. |
| Phosphorus (P) | Max 0.035% | Max 0.035% | Controlled to prevent cold brittleness; no substitution risks. |
| Sulfur (S) | Max 0.035% | Max 0.035% | Limits "hot shortness"; both grades avoid rolling/welding cracks. |
| Trace Elements | Ni (max 0.30%), Cu (max 0.30%) | Ni (max 0.30%), Cu (max 0.30%) | Optional additions enhance corrosion resistance-suitable for coastal China. |
No elemental variance impacts substitution; S355JR channels use the same fabrication processes as Q355B, reducing project costs.