Carbon structural steel grades, their chemical compositions, mechanical properties, and main applications are essential for understanding the material's suitability in various engineering and construction contexts. Below is a detailed overview of different carbon structural steel grades, including their composition, yield strength, tensile strength, elongation, impact resistance, and cold bending capabilities.
**Chemical Composition of Carbon Structural Steel Grades**
| Brand | Grade | Chemical Composition (mass fraction) (%) | Deoxygenation Method |
|-------|--------|------------------------------------------|----------------------|
| | | C | Mn | Si | S | P | |
| Q195 | | ≤0.12 | 0.25–0.50 | ≤0.07 | ≤0.050 | ≤0.045 | F, b, Z |
| Q215 | A | 0.09–0.15 | 0.25–0.55 | ≤0.07 | ≤0.050 | ≤0.045 | F, b, Z |
| | B | ≤0.12 | 0.30–0.70 | ≤0.07 | ≤0.045 | ≤0.045 | – |
| Q235 | A | 0.14–0.22 | 0.30–0.65 | ≤0.07 | ≤0.050 | ≤0.045 | F, b, Z |
| | B | 0.12–0.20 | 0.30–0.70 | ≤0.07 | ≤0.045 | ≤0.045 | – |
| | C | ≤0.18 | 0.35–0.80 | ≤0.07 | ≤0.040 | ≤0.040 | Z |
| | D | ≤0.17 | – | – | ≤0.035 | ≤0.035 | TZ |
| Q255 | A | 0.18–0.28 | 0.40–0.70 | ≤0.07 | ≤0.050 | ≤0.045 | Z |
| | B | ≤0.12 | 0.30–0.70 | ≤0.07 | ≤0.045 | ≤0.045 | – |
| Q275 | | 0.28–0.38 | 0.50–0.80 | ≤0.07 | ≤0.050 | ≤0.045 | Z |
*Note: F stands for boiling steel, b for semi-killed steel, z for killed steel, and TZ for special killed steel.*
- The maximum Mn content for boiling steel grades Q235A and B is 0.60%.
- The Si content in boiling steel is ≤0.07%, in semi-killed steel ≤0.17%, and in killed steel ≤0.12%.
**Yield Point of Carbon Structural Steel**
| Brand | Grade | Yield Point (MPa) | Steel Thickness or Diameter (mm) |
|-------|--------|--------------------|----------------------------------|
| | | ≤16 | >16–40 | >40–60 | >60–100 | >100–150 | >150 |
| Q195 | | 195 | 185 | – | – | – | – |
| Q215 | A, B | 215 | 205 | 195 | 185 | 175 | 165 |
| Q235 | A, B | 235 | 225 | 215 | 205 | 195 | 185 |
| | C, D | 235 | 225 | 215 | 205 | 195 | 185 |
| Q255 | A, B | 255 | 245 | 235 | 225 | 215 | 205 |
| Q275 | | 275 | 265 | 255 | 245 | 235 | 225 |
*Note: The yield point of Q195 is for reference only and not a delivery condition.*
**Tensile Strength, Elongation, and Impact Properties**
| Brand | Tensile Strength (MPa) | Elongation (δ5%) | Impact Test (V-notch, Ak/J) | Temperature (°C) |
|-------|-------------------------|-------------------|----------------------------|------------------|
| Q195 | 315–430 | 33 | – | – |
| Q215 | 335–450 | 31 | 20 | ≥27 |
| Q235 | 375–500 | 26 | 20 | ≥27 |
| Q255 | 410–550 | 24 | 20 | ≥27 |
| Q275 | 490–630 | 20 | – | – |
*Note: Impact values are provided for certain grades at temperatures of 0°C and -20°C.*
**Cold Bending Properties**
| Brand | Sample Orientation | 180° Cold Bending (B=2a/mm) |
|-------|--------------------|------------------------------|
| Q195 | Vertical | – |
| | Horizontal | 0.5a |
| Q215 | Vertical | 0.5a, 1.5a, 2a |
| | Horizontal | a, 2a, 2.5a |
| Q235 | Vertical | a, 2a, 2.5a |
| | Horizontal | 1.5a, 2.5a, 3a |
| Q255 | – | 2a, 3a, 3.5a |
| Q275 | – | 3a, 4a, 4.5a |
*Note: ‘a’ refers to the thickness or diameter of the steel sample.*
**Main Characteristics and Applications**
| Brand | Main Characteristics | Application Examples |
|-------|----------------------|----------------------|
| Q195 | High plasticity, toughness, and weldability; low strength | Anchor bolts, rivets, thin plates, welded pipes, brackets, and structures |
| Q215 | Good formability, weldability, and moderate strength | General parts, beams, and light-duty structures |
| Q235 | Excellent ductility, toughness, and weldability; good cold forming | Wide range of general-purpose parts, building structures, bridges, and machinery |
| Q255 | Good strength, ductility, and weldability | Bolts, keys, shafts, and structural components |
| Q275 | High strength, good machinability, and limited weldability | Gears, sprockets, agricultural machinery, and high-strength parts |
Carbon structural steels are widely used in construction, manufacturing, and engineering due to their balance of strength, ductility, and cost-effectiveness. Each grade is selected based on the specific requirements of the application, such as load-bearing capacity, environmental conditions, and fabrication methods. Understanding these properties helps engineers and designers make informed material choices that ensure safety, durability, and efficiency in their projects.
Imaging Hyperspectral Camera,Hyperspectral Camera 900-1700nm,Hyperspectral Camera 400-100nm
CHNSpec Technology (Zhejiang)Co.,Ltd , https://www.chnspec360.com