Overview
Q235 Carbon Steel is the most widely used structural carbon steel grade in China under the GB/T 700 Standard. It is known for its balanced combination of strength, weldability, formability, machinability, and cost-effectiveness.
The designation “Q” stands for Yield Strength, while “235” indicates a minimum yield strength of 235 MPa.
Q235 is extensively used in:
- Structural Steel Fabrication
- Construction Industry
- Sheet Metal Manufacturing
- Machinery Components
- Steel Frames
- Industrial Equipment
- Automotive Parts
- General Engineering Applications
Compared with Q195 and Q215, Q235 provides higher strength while maintaining excellent processing performance. It is often considered the Chinese equivalent of ASTM A36 mild steel.
Material Specification
| Property | Value |
|---|---|
| Material Designation | Q235 |
| Standard | GB/T 700 |
| Material Family | Carbon Structural Steel |
| Density | 7.85 g/cm³ |
| Magnetic Property | Magnetic |
| Standard Forms | Plate, Sheet, Coil, Tube, Pipe, Bar, Structural Sections |
Q235 Grade Classification
| Grade | Impact Requirement |
|---|---|
| Q235A | No Impact Requirement |
| Q235B | 20°C Impact Test |
| Q235C | 0°C Impact Test |
| Q235D | -20°C Impact Test |
Q235B is the most commonly used grade in international manufacturing projects.
Chemical Composition
Q235B
| Element | Content (%) |
|---|---|
| Iron (Fe) | Balance |
| Carbon (C) | ≤0.20 |
| Manganese (Mn) | ≤1.40 |
| Silicon (Si) | ≤0.35 |
| Sulfur (S) | ≤0.045 |
| Phosphorus (P) | ≤0.045 |
Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | 370–500 MPa |
| Yield Strength | ≥235 MPa |
| Elongation | ≥26% |
| Hardness | 120–170 HB |
| Elastic Modulus | 200 GPa |
Strength Comparison
| Material | Yield Strength |
|---|---|
| Q195 | 195 MPa |
| Q215 | 215 MPa |
| Q235 | 235 MPa |
| Q345 | 345 MPa |
| ASTM A36 | 250 MPa |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | 1460–1520°C |
| Thermal Conductivity | 48–52 W/m·K |
| Electrical Resistivity | 0.16 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 |
Q235 is not corrosion resistant and requires protective coatings for long-term service.
Common surface protection methods include:
- Hot-Dip Galvanizing
- Electro Galvanizing
- Powder Coating
- Painting
- Zinc Plating
- Nickel Plating
- E-Coating
Weldability
| Welding Process | Rating |
|---|---|
| MIG Welding | Excellent |
| TIG Welding | Excellent |
| Arc Welding | Excellent |
| Resistance Welding | Excellent |
| Spot Welding | Excellent |
Q235 is one of the easiest structural steels to weld and fabricate.
Machinability
| Process | Rating |
|---|---|
| CNC Turning | Good |
| CNC Milling | Good |
| Drilling | Excellent |
| Tapping | Excellent |
| Laser Cutting | Excellent |
| Plasma Cutting | Excellent |
| Waterjet Cutting | Excellent |
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| GB/T (China) | Q235 |
| ASTM (USA) | ASTM A36 |
| SAE (USA) | SAE 1020 |
| EN (Europe) | S235JR |
| DIN (Germany) | St37-2 |
| JIS (Japan) | SS400 |
| ISO | E235 |
Available Forms
| Product Type | Availability |
|---|---|
| Hot Rolled Plate | Yes |
| Hot Rolled Sheet | Yes |
| Cold Rolled Sheet | Yes |
| Steel Coil | Yes |
| Round Bar | Yes |
| Square Bar | Yes |
| Angle Steel | Yes |
| Channel Steel | Yes |
| H-Beam | Yes |
| Pipe & Tube | Yes |
Typical Applications
Structural Engineering
- Steel Buildings
- Industrial Structures
- Warehouses
- Platforms
- Support Frames
Sheet Metal Fabrication
- Electrical Cabinets
- Machine Covers
- Enclosures
- Chassis
- Mounting Brackets
Machinery Manufacturing
- Machine Bases
- Equipment Frames
- Mechanical Supports
- Fabricated Assemblies
Construction Industry
- Structural Beams
- Columns
- Reinforcement Structures
- Building Components
Automotive Industry
- Chassis Components
- Structural Parts
- Brackets
- Reinforcement Members
Infrastructure Projects
- Bridges
- Towers
- Utility Structures
- Transportation Equipment
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| Laser Cutting | Excellent |
| CNC Punching | Excellent |
| Bending | Excellent |
| Roll Forming | Excellent |
| Welding | Outstanding |
| Machining | Good |
| Stamping | Excellent |
| Powder Coating | Excellent |
| Galvanizing | Excellent |
Advantages
Excellent Weldability
Ideal for fabricated and welded structures.
Good Mechanical Strength
Suitable for most general engineering applications.
Cost Effective
One of the most economical structural materials.
Excellent Availability
Globally available in multiple forms.
Easy Processing
Supports cutting, bending, welding, and machining.
Widely Accepted Standard
Recognized throughout international manufacturing industries.
Limitations
Poor Corrosion Resistance
Requires protective coating for outdoor use.
Lower Strength Than Q345
Not suitable for high-load structural applications.
Not Heat Treatable
Cannot be significantly strengthened through heat treatment.
Limited Wear Resistance
Not suitable for severe abrasion environments.
Comparison with Other Carbon Steels
| Property | Q235 | Q195 | Q215 | Q345 | ASTM A36 |
|---|---|---|---|---|---|
| Yield Strength | 235 MPa | 195 MPa | 215 MPa | 345 MPa | 250 MPa |
| Weldability | Excellent | Excellent | Excellent | Excellent | Excellent |
| Formability | Excellent | Outstanding | Excellent | Good | Excellent |
| Cost | Low | Lowest | Low | Medium | Medium |
| Structural Use | Excellent | Limited | Moderate | Heavy Duty | Excellent |
Comparison with Engineering Materials
| Material | Yield Strength | Corrosion Resistance | Cost |
|---|---|---|---|
| Q235 | 235 MPa | Poor | Low |
| Q345 | 345 MPa | Poor | Medium |
| ASTM A36 | 250 MPa | Poor | Medium |
| SS304 | 205 MPa | Excellent | High |
| Aluminum 6061-T6 | 276 MPa | Good | High |
| Galvanized Steel | 235 MPa | Good | Medium |
Available Surface Finishes
Raw Finishes
- Hot Rolled Finish
- Cold Rolled Finish
- Pickled Finish
Protective Finishes
- Hot-Dip Galvanizing
- Electro Galvanizing
- Zinc Plating
- Nickel Plating
- Chrome Plating
Decorative Finishes
- Powder Coating
- Spray Painting
- Electrophoretic Coating (E-Coating)
- Silk Screen Printing
Frequently Asked Questions (FAQ)
What is Q235 steel?
Q235 is a low-carbon structural steel under GB/T 700 and is the most commonly used steel grade in China for fabrication and construction.
What is Q235 used for?
Typical applications include:
- Structural Steel Fabrication
- Machinery Components
- Sheet Metal Parts
- Building Structures
- Steel Frames
- Industrial Equipment
What is the difference between Q235 and Q195?
| Property | Q235 | Q195 |
|---|---|---|
| Yield Strength | 235 MPa | 195 MPa |
| Structural Strength | Higher | Lower |
| Fabrication | Excellent | Excellent |
What is the difference between Q235 and Q345?
| Property | Q235 | Q345 |
|---|---|---|
| Yield Strength | 235 MPa | 345 MPa |
| Cost | Lower | Higher |
| Structural Capacity | Medium | High |
Is Q235 equivalent to ASTM A36?
Yes. Q235B is generally considered equivalent to ASTM A36 for most structural applications.
Is Q235 easy to weld?
Yes. Q235 provides excellent weldability and is widely used for welded structures.
Can Q235 be galvanized?
Yes. Galvanizing is one of the most common surface treatments for Q235.
Is Q235 suitable for outdoor use?
Yes, but only with protective coatings such as galvanizing, powder coating, or painting.
Why is Q235 widely used in manufacturing?
Because it combines:
- Good Strength
- Excellent Weldability
- Easy Fabrication
- Low Cost
making it one of the most versatile engineering materials available.
Does GCNOV provide custom manufacturing services for Q235?
Yes. GCNOV provides:
- Laser Cutting
- CNC Machining
- Sheet Metal Fabrication
- Welding
- Structural Fabrication
- Stamping
- Powder Coating
- Galvanizing
- Prototype Development
- Low-Volume Production
- Mass Production