Section Geometry and Role
The 51 x 38 x 5.8 mm channel is a compact C-shaped section with a web height of 51 mm, flange width of 38 mm and web thickness of 5.8 mm. Its U-shaped cross-section provides efficient bending strength around the major axis while leaving one flat face for simple bolted connections, which makes it a practical choice for light frames, brackets and supports.
Grade Requirements: S275JR to EN 10025-2
This channel is supplied in S275JR, a structural grade defined in EN 10025-2. The grade guarantees a minimum yield strength of 275 MPa for thickness up to 16 mm, a tensile range of 410-560 MPa and a minimum Charpy V-notch energy of 27 J at 20 degrees Celsius. The JR suffix indicates the room-temperature impact class, which is suitable for general indoor and mild outdoor applications.
Mill Finish and Surface Condition
Mill finish means the section is delivered as rolled, with the natural oxide layer and residual rolling scale on the surface. The finish is free of loose rust, pitting and laminations, and is the economical starting point when the component will be painted, galvanized or used in a dry indoor environment.
Dimensional Tolerances and Lengths
Web height, flange width, thickness and straightness are controlled to the tolerances of the governing standard, with thickness checked at a defined distance from the flange edge. Sections are supplied in standard lengths of 6 m, with cutting to exact length, punching or drilling available before despatch.
Fabrication and Protection
S275JR welds readily with MIG, TIG or MMA processes and standard filler metals. The section can be drilled, punched, notched and cold-bent within normal limits. For outdoor service, hot-dip galvanizing to BS EN ISO 1461 or a paint system is applied; for indoor use, the mill finish can be left as supplied or given a light primer.
Typical Applications
Support brackets and fixing rails in building services
Light machine frames and equipment stands
Door and window frame reinforcement
Cable tray supports and pipe clamps
Small-scale agricultural and workshop structures
Frequently Asked Questions
Q: What does S275JR mean?
S is structural steel, 275 is the minimum yield strength in MPa, and JR means the material must achieve 27 J Charpy impact energy at room temperature of 20 degrees Celsius.
Q: Is the 51 x 38 x 5.8 mm channel available in other grades?
Equivalent grades such as Q235 to GB/T 700-2006, SS400 to JIS G3101 and ASTM A36 are commonly available for the same section geometry.
Q: What does mill finish look like?
Mill finish is the natural as-rolled surface with a dark oxide layer and rolling scale. It is uniform, free of loose scale and suitable for subsequent painting or galvanizing.
Q: Can this channel be hot-dip galvanized?
Yes. The section is suitable for hot-dip galvanizing to BS EN ISO 1461, which is recommended when it will be used outdoors or in humid conditions.
Q: What standard length is supplied?
The normal supply length is 6 m, and cutting to exact length can be arranged according to the fabrication requirements.
Q: Where is a 51 x 38 mm channel typically used?
It is used for light frames, brackets, rails and supports where the load is moderate and the section must be easy to connect by bolting or welding.