Overview
Q275 Carbon Steel is a medium-strength carbon structural steel grade specified under GB/T 700 Standard. It offers higher strength and hardness than Q235 while maintaining good weldability, machinability, and fabrication performance.
The designation “Q” represents Yield Strength, and “275” indicates a minimum yield strength of 275 MPa.
Q275 is widely used in:
- Structural Engineering
- Heavy Equipment Manufacturing
- Mechanical Components
- Steel Fabrication
- Construction Machinery
- Agricultural Equipment
- Industrial Equipment
- Transportation Structures
Compared with Q235, Q275 provides improved load-bearing capacity and wear resistance, making it suitable for more demanding engineering applications.
Material Specification
| Property | Value |
|---|---|
| Material Designation | Q275 |
| Standard | GB/T 700 |
| Material Family | Carbon Structural Steel |
| Density | 7.85 g/cm³ |
| Magnetic Property | Magnetic |
| Standard Forms | Plate, Sheet, Bar, Structural Sections, Pipe, Tube |
Q275 Grade Classification
| Grade | Impact Requirement |
|---|---|
| Q275A | Standard Grade |
| Q275B | Improved Mechanical Properties |
Q275B is commonly selected for structural fabrication and machinery manufacturing.
Chemical Composition
Q275B
| Element | Content (%) |
|---|---|
| Iron (Fe) | Balance |
| Carbon (C) | ≤0.28 |
| Manganese (Mn) | ≤1.50 |
| Silicon (Si) | ≤0.35 |
| Sulfur (S) | ≤0.050 |
| Phosphorus (P) | ≤0.045 |
Compared with Q235, the higher carbon content contributes to increased strength and hardness.
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | 410–540 MPa |
| Yield Strength | ≥275 MPa |
| Elongation | ≥21% |
| Hardness | 140–190 HB |
| Elastic Modulus | 200 GPa |
Strength Comparison
| Material | Yield Strength |
|---|---|
| Q195 | 195 MPa |
| Q215 | 215 MPa |
| Q235 | 235 MPa |
| Q275 | 275 MPa |
| Q345 | 345 MPa |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | 1460–1520°C |
| Thermal Conductivity | 48 W/m·K |
| Electrical Resistivity | 0.17 μΩ·m |
| Thermal Expansion Coefficient | 11.7 × 10⁻⁶/K |
| Specific Heat Capacity | 486 J/kg·K |
Corrosion Resistance
| Environment | Performance |
|---|---|
| Indoor Environment | Moderate |
| Dry Atmosphere | Good |
| Industrial Environment | Poor |
| Outdoor Exposure | Poor |
| Marine Environment | Very Poor |
| Chemical Environment | Poor |
Like most carbon steels, Q275 requires corrosion protection when exposed to outdoor or humid environments.
Recommended surface treatments include:
- Hot-Dip Galvanizing
- Zinc Plating
- Powder Coating
- Painting
- E-Coating
- Nickel Plating
Weldability
| Welding Process | Rating |
|---|---|
| MIG Welding | Good |
| TIG Welding | Good |
| Arc Welding | Good |
| Resistance Welding | Good |
| Spot Welding | Good |
Although Q275 remains highly weldable, its higher carbon content requires greater attention to heat input compared with Q235.
For thick sections, preheating may be recommended.
Machinability
| Process | Rating |
|---|---|
| CNC Turning | Good |
| CNC Milling | Good |
| Drilling | Excellent |
| Tapping | Good |
| Grinding | Good |
| Laser Cutting | Excellent |
| Plasma Cutting | Excellent |
Q275 offers better machinability and wear resistance than lower-carbon structural steels.
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| GB/T (China) | Q275 |
| ASTM (USA) | ASTM A570 Grade 40 |
| SAE (USA) | SAE 1025 |
| EN (Europe) | S275JR |
| DIN (Germany) | St44-2 |
| JIS (Japan) | SS490 |
| ISO | E275 |
Available Forms
| Product Type | Availability |
|---|---|
| Hot Rolled Plate | Yes |
| Hot Rolled Sheet | Yes |
| Steel Coil | Yes |
| Round Bar | Yes |
| Flat Bar | Yes |
| Angle Steel | Yes |
| Channel Steel | Yes |
| H-Beam | Yes |
| Pipe & Tube | Yes |
Typical Applications
Structural Engineering
- Industrial Buildings
- Steel Structures
- Platforms
- Support Frames
- Structural Members
Heavy Machinery
- Equipment Frames
- Machine Bases
- Load-Bearing Structures
- Mechanical Supports
Construction Equipment
- Excavator Components
- Crane Structures
- Loader Parts
- Structural Brackets
Transportation Industry
- Trailer Frames
- Vehicle Chassis
- Railway Components
- Logistics Equipment
Agricultural Equipment
- Farm Machinery
- Equipment Frames
- Structural Supports
General Manufacturing
- Welded Assemblies
- Fabricated Components
- Industrial Equipment Parts
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| Laser Cutting | Excellent |
| Plasma Cutting | Excellent |
| CNC Machining | Good |
| Welding | Good |
| Bending | Good |
| Roll Forming | Good |
| Structural Fabrication | Excellent |
| Galvanizing | Excellent |
| Powder Coating | Excellent |
Advantages
Higher Strength Than Q235
Suitable for heavier load-bearing applications.
Good Weldability
Supports most industrial welding processes.
Cost Effective
Less expensive than high-strength alloy steels.
Excellent Availability
Widely stocked in structural forms.
Good Machinability
Suitable for fabrication and machining operations.
Reliable Structural Performance
Commonly used in engineering and construction projects.
Limitations
Lower Corrosion Resistance
Requires protective coatings for outdoor service.
Reduced Formability Compared to Q195/Q235
Higher carbon content slightly reduces ductility.
Not Heat Treatable for High Hardness
Cannot achieve the hardness levels of alloy steels.
Lower Strength Than Q345
Not suitable for heavy-duty high-strength applications.
Comparison with Other Carbon Steels
| Property | Q275 | Q235 | Q345 | ASTM A36 | S275JR |
|---|---|---|---|---|---|
| Yield Strength | 275 MPa | 235 MPa | 345 MPa | 250 MPa | 275 MPa |
| Tensile Strength | 410–540 MPa | 370–500 MPa | 470–630 MPa | 400–550 MPa | 410–560 MPa |
| Weldability | Good | Excellent | Excellent | Excellent | Excellent |
| Cost | Low | Lower | Medium | Medium | Medium |
Comparison with Engineering Materials
| Material | Yield Strength | Corrosion Resistance | Cost |
|---|---|---|---|
| Q275 | 275 MPa | Poor | Low |
| Q235 | 235 MPa | Poor | Low |
| Q345 | 345 MPa | Poor | Medium |
| SS304 | 205 MPa | Excellent | High |
| Aluminum 6061-T6 | 276 MPa | Good | High |
| ASTM A36 | 250 MPa | Poor | Medium |
Available Surface Finishes
Raw Finishes
- Hot Rolled Finish
- Pickled Finish
- Shot Blasted Finish
Protective Finishes
- Hot-Dip Galvanizing
- Electro Galvanizing
- Zinc Plating
- Nickel Plating
- Chrome Plating
Decorative Finishes
- Powder Coating
- Spray Painting
- Electrophoretic Coating (E-Coating)
- Industrial Paint Systems
Frequently Asked Questions (FAQ)
What is Q275 steel?
Q275 is a medium-strength carbon structural steel with a minimum yield strength of 275 MPa and excellent suitability for fabrication and structural applications.
What is Q275 used for?
Typical applications include:
- Structural Steel Fabrication
- Heavy Equipment Frames
- Construction Machinery
- Transportation Structures
- Industrial Equipment
- Agricultural Machinery
What is the difference between Q275 and Q235?
| Property | Q275 | Q235 |
|---|---|---|
| Yield Strength | 275 MPa | 235 MPa |
| Load Capacity | Higher | Lower |
| Hardness | Higher | Lower |
| Formability | Slightly Lower | Better |
What is the difference between Q275 and Q345?
| Property | Q275 | Q345 |
|---|---|---|
| Yield Strength | 275 MPa | 345 MPa |
| Cost | Lower | Higher |
| Structural Capacity | Medium | High |
Is Q275 easy to weld?
Yes. Q275 offers good weldability, although thick sections may require preheating.
Can Q275 be galvanized?
Yes. Q275 is frequently hot-dip galvanized for outdoor and structural applications.
Is Q275 equivalent to S275JR?
Yes. Q275 is generally considered equivalent to EN S275JR for structural engineering applications.
Is Q275 suitable for structural applications?
Yes. Q275 is widely used for medium-duty structural engineering projects.
Why is Q275 used in machinery manufacturing?
Because it combines:
- Good Strength
- Good Weldability
- Cost Efficiency
- Excellent Availability
making it ideal for fabricated mechanical structures.
Does GCNOV provide custom manufacturing services for Q275?
Yes. GCNOV provides:
- CNC Machining
- Laser Cutting
- Plasma Cutting
- Structural Fabrication
- Welding
- Sheet Metal Fabrication
- Galvanizing
- Powder Coating
- Prototype Development
- Low-Volume Production
- Mass Production