Q235 is the most common carbon structural steel in China. You’ll encounter it everywhere—from general construction to low-strength fasteners. But what exactly is in it, and how strong is it?
What Does Q235 Mean?
-
Q = “Qu” (屈服) — Chinese for yield point
-
235 = Minimum yield strength in MPa (for thickness ≤16mm)
Q235 is further divided into quality grades A, B, C, D, which indicate different impact test requirements and slight variations in composition.
| Grade | Impact Test | Typical Use |
|---|---|---|
| Q235A | No impact test required | General structures, non-critical parts |
| Q235B | Room temperature impact (20°C) | Welded structures, slightly higher quality requirements |
| Q235C | 0°C impact test | Low-temperature applications |
| Q235D | -20°C impact test | Critical low-temperature service |
Chemical Composition
The table below shows the chemical composition ranges for Q235 based on GB/T 700. Note that actual values vary by mill and heat—always refer to the mill certificate.
| Element | Q235A | Q235B | Q235C | Q235D |
|---|---|---|---|---|
| Carbon (C) | 0.14-0.22% | 0.12-0.20% | ≤0.18% | ≤0.17% |
| Silicon (Si) | ≤0.30% | ≤0.30% | ≤0.30% | ≤0.30% |
| Manganese (Mn) | 0.30-0.65% | 0.30-0.70% | 0.35-0.80% | 0.35-0.80% |
| Phosphorus (P) | ≤0.045% | ≤0.045% | ≤0.040% | ≤0.035% |
| Sulfur (S) | ≤0.050% | ≤0.045% | ≤0.040% | ≤0.035% |
| Chromium (Cr) | ≤0.30% (residual) | ≤0.30% (residual) | ≤0.30% (residual) | ≤0.30% (residual) |
| Nickel (Ni) | ≤0.30% (residual) | ≤0.30% (residual) | ≤0.30% (residual) | ≤0.30% (residual) |
| Copper (Cu) | ≤0.30% (residual) | ≤0.30% (residual) | ≤0.30% (residual) | ≤0.30% (residual) |
Mechanical Properties：Tensile and Yield Strength
Q235’s mechanical properties depend on thickness. Thicker sections have lower yield strength requirements.
| Thickness (mm) | Yield Strength (MPa) min | Tensile Strength (MPa) |
|---|---|---|
| ≤16 | 235 | 370-500 |
| >16 – 40 | 225 | 370-500 |
| >40 – 60 | 215 | 370-500 |
| >60 – 100 | 205 | 370-500 |
| >100 – 150 | 195 | 370-500 |
| >150 | 185 | 370-500 |
Tensile strength for all Q235 grades is 370-500 MPa regardless of thickness.
Summary: Q235 at a Glance
| Property | Value |
|---|---|
| Standard | GB/T 700 |
| Grades | A, B, C, D (increasing quality) |
| Yield Strength | 235 MPa (≤16mm) to 185 MPa (>150mm) |
| Tensile Strength | 370-500 MPa |
| Carbon Range | 0.12-0.22% (varies by grade) |
| Key Features | Good weldability, formability, low cost |
| Fastener Use | Class 4.6 and 4.8 only |
No products in the cart.