Q235 steel is a widely used mild carbon structural steel with moderate strength, good bearing capacity, plasticity, toughness, and weldability. It is the most commonly used steel in general fabrication, construction, machinery, and structural applications.
The name "Q235" represents:
235: Nominal yield strength of ~235 MPa (decreases with increasing thickness)
Q235 Grades and Impact Temperature
Q235 is divided into four quality grades (A, B, C, D), mainly distinguished by impact performance at different temperatures:
| Q235A | ||
| Q235B | 20 ℃ (room temperature) | |
| Q235C | 0 ℃ | Suitable for low-temperature applications |
| Q235D | −20 ℃ | Best low-temperature toughness, suitable for very cold environments |
Lower C, P, and S improve flexibility, weldability, and impact resistance.
| C (%) | S (%) | P (%) | ||||
|---|---|---|---|---|---|---|
| Q235A | 0.14–0.22 | 0.30–0.70 | <=0.03 | <=0.045 | 0.045 | |
| Q235B | 0.12–0.20 | 0.30–0.70 | <=0.03 | <=0.045 | 0.045 | |
| Q235C | <=0.18 | 0.35–0.70 | <=0.03 | <=0.040 | 0.040 | |
| Q235D | <=0.17 | 0.35–0.70 | <=0.03 | <=0.035 | 0.035 | Best performance, full mechanical + impact testing |
Boiling Steel (F): Not fully deoxidized; plasticity and toughness are poorer; welded structures prone to cracking under dynamic load. Not suitable for low-temperature use.
Calm/Flat Steel (B/Z): Fully deoxidized; excellent uniformity, plasticity, and toughness; preferred for welded structures.
| Q235 (general) | ||
|---|---|---|
| 375–500 MPa | ||
| Elongation (δ5) | >=26% (d <=16 mm) >=25% (16–40 mm) >=24% (40–60 mm) >=23% (60–100 mm) >=22% (100–150 mm) ≥21% (d >150 mm) |
A=thickness or diameter |
| >=235 MPa | ||
Q235A: only chemical inspection, mechanical properties not mandatory
Q235B: partial mechanical inspection
Q235C/D: full mechanical inspection, including impact tests
Q235 steel is widely used for:
Q235 is a versatile, cost-effective, and widely available structural steel. Its grades (A–D) allow selection based on impact temperature requirements and mechanical performance testing.
The combination of moderate strength, good weldability, plasticity, and toughness makes it suitable for a wide range of industrial and construction applications.
