Q235 Channel steel is a highly common and versatile hot-rolled structural steel channel, widely used in construction and manufacturing across China and in international projects. Its name derives from its two key characteristics: its material grade (Q235) and its cross-sectional shape (Channel or C-Shape).

Key Mechanical Properties of Q235 Steel:

Yield Strength (σs): ≥ 235 MPa

Tensile Strength (σb): 370 - 500 MPa

Elongation (δ5): ≥ 26% (indicates good ductility)

Note: The properties can vary slightly between thicknesses.

Q235 is roughly equivalent to other international grades like:

US ASTM: A36 (though A36 has a slightly higher yield strength of 250 MPa)

European EN: S235JR

Japanese JIS: SS400

2. Shape: Channel Steel (U-Channel or C-Channel)

Channel steel gets its name from its distinctive "C" or "U" shaped cross-section. It consists of a vertical web and two horizontal flanges (or legs) at the top and bottom.

Standard Dimensions (per GB/T 706-2016):

Channels are typically designated by their model number, which represents the nominal height of the web in centimeters.

Common Sizes: Ranges from small channels like 50x37mm (5# channel) to large ones like 400x104mm (40# channel).

Key Dimensions:

Height (h): The depth of the web.

Flange Width (b): The width of the two horizontal flanges.

Web Thickness (d): The thickness of the vertical section.

Flange Thickness (t): The thickness of the horizontal flanges.

Weight: The theoretical weight is usually expressed in kilograms per meter (kg/m).

3. Manufacturing Process

Q235 Channel Steel is primarily produced through hot rolling. This process involves heating steel billets to a high temperature (over 1,100°C) and then passing them through a series of rollers to achieve the desired C-shape profile. This method is efficient for mass production and results in a product with good structural integrity.

4. Key Characteristics and Advantages

Cost-Effective: Q235 is one of the most economical structural steel grades available.

Good Weldability: It can be easily welded using all standard methods without requiring pre-heating in most cases.

Excellent Machinability: It can be easily cut, drilled, and formed, making it adaptable to various project needs.

Adequate Strength: With a yield strength of 235 MPa, it provides sufficient load-bearing capacity for a vast range of applications.

Ductility: Its good elongation property allows it to bend and deform to some extent before fracturing, which is a critical safety feature in structures.

5. Common Applications

Due to its balance of strength, workability, and cost, Q235 Channel Steel is ubiquitous in:

Building and Construction: As purlins and rafters in industrial buildings, warehouse frameworks, mezzanine floors, and support frames.

Machinery and Vehicle Manufacturing: As frames, braces, and supports for machinery, truck trailers, and equipment.

Infrastructure: In bridges, transmission towers, and various structural supports.

General Fabrication: For making shelves, racks, stairs, and countless other custom fabrications.

6. Comparison with Q345 Channel Steel

Q345 is a higher-strength low-alloy steel with a yield strength of 345 MPa. While stronger, it is also more expensive. Q235 is chosen where the higher strength of Q345 is not necessary, offering a more budget-friendly solution for medium-duty applications.