Here's a concise technical overview of Q235B steel based on the Chinese standard GB/T 700-2006 (Carbon Structural Steels):
"Q": Indicates yield strength (Chinese: Qu)
"235": Minimum yield strength of 235 MPa at ≤16mm thickness.
"B": Quality grade (B is medium-tier, requiring impact testing at 20°C).
| Element | Max % (Thickness ≤40mm) |
|---|---|
| Carbon (C) | 0.12–0.20 |
| Manganese (Mn) | 0.30–0.70 |
| Silicon (Si) | ≤0.30 |
| Sulfur (S) | ≤0.045 |
| Phosphorus (P) | ≤0.045 |
| Property | Value |
|---|---|
| Yield Strength (Re) | ≥235 MPa (for ≤16mm thickness; decreases with thicker sections) |
| Tensile Strength (Rm) | 370–500 MPa |
| Elongation (A₅) | ≥26% |
| Impact Energy (KV₂ at 20°C) | ≥27 J |
ASTM: Similar to A36 (but not identical; A36 has higher Mn content).
EN (Europe): Closest to S235JR (EN 10025-2).
Structural frameworks, buildings, bridges.
Machinery parts, bolts, welded components.
General fabrication where moderate strength and weldability are required.
Weldability: Good (preheat if thickness >30mm).
Surface: Often supplied as hot-rolled (black steel) or galvanized.
Limitations: Not suitable for low-temperature applications (use Q345B/D for ≤-20°C).
Cost-effective for general structural use.
Balances strength and ductility.
Widely available in plates, coils, bars, and sections.
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