Q355B Steel: Chemical Composition and Mechanical Properties
Q355B Steel: Chemical Composition and Mechanical Properties,whatsapp ID +8618540208906
Q355B Steel: Chemical Composition and Mechanical Properties
1. Chemical Composition (GB/T 1591 Standard):
Q355B is a low-alloy high-strength structural steel. Its typical composition (maximum values, unless stated otherwise) is:
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Carbon (C): ≤0.20%
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Silicon (Si): ≤0.55%
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Manganese (Mn): ≤1.60%
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Phosphorus (P): ≤0.035%
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Sulfur (S): ≤0.035%
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Micro-alloying elements (e.g., V, Nb, Ti): Added in trace amounts (≤0.15% combined) for grain refinement and strength.
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Carbon Equivalent (CEV): ~0.40–0.45 (for weldability assessment).
2. Mechanical Properties:
Properties vary with material thickness (hot-rolled condition):
| Thickness (mm) | Yield Strength (MPa) | Tensile Strength (MPa) | Elongation (%) |
|---|---|---|---|
| ≤16 | ≥355 | 470–630 | ≥22 |
| 16–40 | ≥345 | 470–630 | ≥22 |
| 40–63 | ≥335 | 470–630 | ≥21 |
| 63–80 | ≥325 | 470–630 | ≥21 |
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Impact Toughness (Charpy V-notch): ≥34J at 20°C (Grade B requirement).
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Density: ~7.85 g/cm³.
3. Key Notes:
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Applications: Widely used in bridges, buildings, and machinery due to balanced strength and weldability.
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Comparable Grades: EN S355JR or ASTM A572 Gr 50 (similar properties, but verify exact equivalence).
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Processing: Typically supplied hot-rolled; properties may adjust with heat treatment or controlled rolling.