C section (cold-formed channel) and hot-rolled channel (U-channel or C-channel) are both channel-shaped steel profiles, but they are produced by fundamentally different processes that affect their geometry, mechanical properties, and suitable applications. This comparison helps specifiers choose the right profile for their project.
Hot-rolled channel is produced by passing heated steel billets through a series of rolling stands that progressively shape the web and tapered flanges. The process operates at temperatures above the recrystallization point (approximately 1,100°C), resulting in a profile with slightly rounded internal corners, tapered flange tips, and a characteristic mill scale surface. Standard hot-rolled channels conform to GB/T 706, EN 10279, or ASTM A6.
Cold-formed C section is produced at ambient temperature by roll-forming galvanized or cold-rolled steel strip through a series of rollers that progressively bend the strip into the channel profile. The process yields a section with uniform thickness, sharp internal corners, and parallel flange surfaces. Cold-formed C sections are governed by GB/T 6723, EN 1993-1-3, or AISI S100.
Hot-rolled channels have tapered flanges — the inner flange surface slopes at approximately 8% (1:12), while the outer surface is also slightly tapered. The web-to-flange junction has a radius (fillet) of approximately 6–12 mm depending on section size. These geometric features affect bolted connection design, as washers may not seat flat on the tapered surface.
Cold-formed C sections have parallel flange surfaces with small bend radii at corners (typically 1–3 times the material thickness). This geometry simplifies bolted connections and allows direct surface contact without tapered washers. C sections are designated by web depth × flange width × lip length × thickness, e.g., C160×60×20×2.0.
Hot-rolled channel is available in Q235B (yield 235 MPa) and Q345B (yield 345 MPa). The hot-rolling process relieves residual stresses from forming, and the thicker sections (up to 20+ mm in web/flange) provide substantial buckling resistance for column and primary beam applications.
Cold-formed C section typically uses Q235B or Q345B substrate with yield strengths of 235–345 MPa. However, the cold-forming process introduces residual stresses and strain hardening at the bent corners that affect section behavior. Thin-gauge C sections (under 3.0 mm) are susceptible to local buckling and distortional buckling modes not present in hot-rolled sections. Design codes for cold-formed steel account for these failure modes through effective width methods.
Hot-rolled channel is specified for primary structural members: building columns, crane runway beams, truck chassis frames, machine bases, and heavy equipment supports where robustness and load capacity govern selection. Standard sizes range from 50 × 37 mm (5.59 kg/m) to 400 × 104 mm (71.5 kg/m) in Chinese standard profiles.
Cold-formed C section is the standard profile for secondary structural members: roof purlins, wall girts, cladding support rails, mezzanine floor joists, and light-gauge steel framing for residential and low-rise commercial buildings. C sections are typically used in thicknesses from 1.5 mm to 3.0 mm, though heavier gauges to 6.0 mm are available for specific applications.
Cold-formed C sections are generally more economical per meter for light-gauge applications, as the roll-forming process is continuous and efficient, and the thinner material uses less steel. Hot-rolled channels carry a higher per-meter cost due to the heavier section weight, but offer greater load capacity per unit length for primary structural applications.
TXD Steel Profile manufactures cold-formed C sections in its own roll-forming lines and stocks hot-rolled channels in the full GB/T 706 size range. For projects requiring both primary (hot-rolled) and secondary (cold-formed) steel, TXD can consolidate both profile types in single shipments.
Contact TXD Steel Profile / Shandong TXD Steel Group
