Q195, Q215, Q235, and Q275 are all Chinese standard carbon structural steels, widely used for H-beams in construction and engineering projects. The differences between these steel grades lie in their chemical composition, yield strength, and tensile strength, which determine their suitability for different structural applications.
Chemical Composition
| Steel Series | Grade | C % (≤) | Si % (≤) | Mn % (≤) | P % (≤) | S % (≤) |
|---|---|---|---|---|---|---|
| Q195 | Q195 | 0.12 | 0.30 | 0.50 | 0.035 | 0.04 |
| Q215 | Q215A | 0.15 | 0.35 | 1.20 | 0.045 | 0.05 |
| Q215B | 0.15 | 0.35 | 1.20 | 0.045 | 0.045 | |
| Q235 | Q235A | 0.22 | 0.35 | 1.40 | 0.045 | 0.05 |
| Q235B | 0.20 | 0.35 | 1.40 | 0.045 | 0.045 | |
| Q235C | 0.17 | 0.35 | 1.40 | 0.040 | 0.040 | |
| Q235D | 0.17 | 0.35 | 1.40 | 0.035 | 0.035 | |
| Q275 | Q275A | 0.24 | 0.35 | 1.50 | 0.045 | 0.05 |
| Q275B | 0.21 | 0.35 | 1.50 | 0.045 | 0.045 | |
| Q275C | 0.20 | 0.35 | 1.50 | 0.040 | 0.040 | |
| Q275D | 0.20 | 0.35 | 1.50 | 0.035 | 0.035 |
Notes:
Carbon (C) content increases from Q195 to Q275, enhancing strength but slightly reducing weldability and plasticity.
Manganese (Mn) and silicon (Si) contribute to strength and toughness.
Phosphorus (P) and sulfur (S) are impurities; lower values in higher grades improve toughness and reduce brittleness.
Mechanical Properties
| Steel Grade | Yield Strength (MPa) | Tensile Strength (MPa) |
|---|---|---|
| Q195 | 195 | 315–430 |
| Q215 | 215 | 335–450 |
| Q235 | 235 | 370–500 |
| Q275 | 275 | 410–540 |
Key Takeaways:
Q195: Low yield strength, suitable for lightweight structures and small-scale H-beams.
Q215: Moderate strength for standard structural applications.
Q235: Most widely used for H-beams in general construction due to a balance of strength, ductility, and weldability.
Q275: Higher strength steel, ideal for heavy-duty structures, bridges, or components with higher load requirements.
Applications for H-Beams
Q195 & Q215: Residential buildings, small steel frameworks, and temporary support structures.
Q235: Industrial buildings, factories, warehouses, and general-purpose H-beams.
Q275: Large-scale construction, bridges, heavy machinery frames, and high-strength load-bearing H-beams.
