What Is S275JR Channel Steel
S275JR is a structural steel grade defined in EN 10025-2, with the number 275 indicating a minimum yield strength of 275 MPa for thickness up to 16 mm. When rolled as a channel, the steel forms a U-shaped section with a web and two flanges on the same side, providing efficient bending strength in one direction and a convenient shape for bolted connections. The JR designation guarantees 27 J impact energy at +20 °C.
Chemical Composition
Per EN 10025-2, S275JR limits the main elements as follows for thickness up to 40 mm:
Carbon - 0.24% maximum, keeping the steel readily weldable.
Manganese - 1.50% maximum, providing strength through solid solution hardening.
Phosphorus - 0.040% maximum, and sulphur 0.040% maximum for cleanliness.
Nitrogen - 0.014% maximum, with a minimum aluminium content required when nitrogen fixing elements are absent.
Mechanical Performance
Yield strength - 275 MPa minimum for thickness up to 16 mm, reducing to 255 MPa for 40-63 mm.
Tensile strength - 410-560 MPa for thickness up to 16 mm, and 410-540 MPa for 16-40 mm.
Elongation - minimum 21% on the standard proportional test piece.
Impact toughness - 27 J minimum at +20 °C for the JR designation.
Performance in Service
The composition gives S275JR a carbon equivalent below about 0.40%, which means the channel can be welded by all conventional processes without preheat in normal thicknesses. It forms well by cold bending, punches and drills cleanly, and is fully suitable for hot-dip galvanizing. The grade offers a good balance between strength and ductility, so it performs reliably in frames, bracing and secondary members.
Typical Channel Applications
Building frames - columns, purlins, eaves beams and bracing members.
Industrial structures - equipment skids, cable trays, ladder and walkway supports.
Transport and trailers - chassis rails and cross members.
General fabrication - brackets, lintels, posts and framework for gates and barriers.
Frequently Asked Questions
Q: What does S275JR stand for?
S means structural steel, 275 is the minimum yield strength in MPa for thickness up to 16 mm, J refers to impact test requirements and R means room temperature at +20 °C.
Q: Can S275JR channel be welded without preheat?
Yes, in most thickness ranges the low carbon equivalent allows welding without preheat using standard electrodes or MIG wire.
Q: What channel sizes are standard?
Channels are available in European UPN and UPE series, JIS channels and Chinese C series, with depths from 50 mm to 400 mm.
Q: Is S275JR stronger than S235JR?
Yes, S275JR guarantees 275 MPa yield versus 235 MPa for S235JR, allowing lighter sections for the same load.
Q: Can the channel be galvanized?
Yes, S275JR channels are routinely hot-dip galvanized per ISO 1461 for outdoor and industrial corrosion protection.
Q: What certificates are supplied?
Mill test certificates per EN 10204 type 3.1 state the heat analysis, mechanical test results and rolling details.