Steel square bars — also referred to as square bar steel, square section bars or square rod — are hot rolled solid steel profiles with a uniform square cross-section. Combining structural rigidity with excellent machinability, steel square bars serve as versatile stock material across mechanical engineering, construction, tooling and general fabrication. ULAMEX supplies hot rolled square bars manufactured to EN 10059 in side lengths from 8 mm to 100 mm, produced from non-alloy structural steel grades S235JR and S355J2 per EN 10025-2. Cold-drawn square bars are available on request for applications requiring tighter tolerances. Standard stock length is 6,000 mm, available for immediate dispatch from our European warehouse.
Material Grades and Standards
Our steel square bars are manufactured from carbon steel conforming to EN 10025-2, the European standard for non-alloy structural steels. Two grades are kept in permanent stock:
- S235JR (material number 1.0038) — minimum yield strength of 235 MPa, tensile strength 360–510 MPa, and guaranteed Charpy V-notch impact energy of 27 J at +20°C. Formerly designated St37-2 (DIN 17100) and equivalent to ASTM A36, S235JR is the standard structural steel for general fabrication, brackets, fixtures and machine components where moderate strength and good workability are the primary requirements.
- S355J2 (material number 1.0577) — minimum yield strength of 355 MPa, tensile strength 470–630 MPa, with guaranteed impact toughness of 27 J at -20°C. Previously known as St52-3 and comparable to ASTM A572 Grade 50, S355J2 is specified for load-bearing components, tooling applications, and structures subjected to dynamic or low-temperature loading where the higher strength-to-weight ratio of this grade reduces material consumption and overall weight.
Both grades offer excellent weldability with a carbon equivalent (CEV) below 0.45, permitting all standard welding methods — MIG/MAG, MMA (electrode), TIG and submerged arc welding — without mandatory preheating for typical cross-sections. S275JR (1.0044) and other grades per EN 10025-2 are available on request.
Hot rolled square bars are produced in compliance with the dimensional standard EN 10059 (Hot rolled square steel bars — dimensions and tolerances on shape and dimensions), which defines cross-sectional geometry, corner radii, dimensional tolerances and mass-per-metre values. For cold-drawn bright square bars, the governing standard is EN 10278, providing tighter tolerances (h11 or h9) and improved surface finish suitable for precision engineering applications.
Dimensions and Specifications
ULAMEX stocks steel square bars in the following standard side lengths per EN 10059:
- 8 mm — approx. 0.502 kg/m
- 10 mm — approx. 0.785 kg/m
- 12 mm — approx. 1.130 kg/m
- 14 mm — approx. 1.540 kg/m
- 16 mm — approx. 2.010 kg/m
- 20 mm — approx. 3.140 kg/m
- 25 mm — approx. 4.910 kg/m
- 30 mm — approx. 7.065 kg/m
- 35 mm — approx. 9.620 kg/m
- 40 mm — approx. 12.560 kg/m
- 50 mm — approx. 19.630 kg/m
- 60 mm — approx. 28.260 kg/m
- 70 mm — approx. 38.470 kg/m
- 80 mm — approx. 50.240 kg/m
- 90 mm — approx. 63.590 kg/m
- 100 mm — approx. 78.500 kg/m
Mass-per-metre values are calculated based on a steel density of 7,850 kg/m³ and nominal side dimensions. All square bar steel is supplied in a standard length of 6,000 mm (6 m). Custom cut-to-size lengths are available on request. Dimensional tolerances for hot rolled square bars conform to EN 10059 class 1 requirements for side length, corner radius, twist and straightness. Cold-drawn square bars per EN 10278 are available in tolerance classes h11 and h9 for applications demanding higher dimensional accuracy.
Applications of Steel Square Bars
Steel square bars occupy a distinctive position among solid bar products: their four flat faces provide stable seating and alignment in assemblies, while the uniform cross-section ensures consistent material properties in all directions within the plane. This makes square bar steel exceptionally versatile across a wide range of industrial applications:
- Machine components and mechanical engineering — square bars serve as raw stock for the production of shafts with keyway sections, couplings, adaptor blocks, gear blanks, slide guides and linear bearing housings. The square profile provides natural anti-rotation characteristics, eliminating the need for separate keying arrangements in many power transmission assemblies.
- Brackets, fixtures and jigs — the flat surfaces of square bar make it ideal for welded and bolted bracket fabrication, clamping fixtures in CNC machining centres, welding jigs, assembly fixtures and workholding devices where flat reference surfaces are essential for accurate positioning.
- Tooling and die components — square bars in S355J2 are machined into die spacers, press columns, guide pillars, stripper plates and backing blocks in stamping and forming tool sets. The higher yield strength of S355J2 provides additional resistance to compressive deformation under repeated loading cycles.
- Spacers, shims and packing pieces — precision-sawn square bar sections serve as load-bearing spacers in bolted connections, base plate shimming in structural steelwork, and machine levelling pads. Cold-drawn bright square bars with h9 tolerance are preferred where tight dimensional control is critical.
- Construction and structural steelwork — square bars are used as stiffener elements, embedded anchors in concrete connections, balustrade and handrail infill bars, and lattice girder chord members in lightweight truss construction. In decorative metalwork, the clean square profile provides an attractive architectural element for gates, fences and railings.
- Agricultural and material handling equipment — square bars form key components in plough shares, cultivator tines, harrow teeth, conveyor guide rails, hopper chutes and bin construction where the square profile resists rotation and provides a robust wearing surface.
- General fabrication and welded assemblies — frames, supports, cross-members, hinges, latches, stops and bumpers in industrial, commercial and residential metalwork. The square section provides high torsional stiffness relative to its weight, making it an efficient choice for frame and chassis structures.
Technical Properties
Hot rolled steel square bars in grades S235JR and S355J2 offer a well-balanced combination of strength, ductility and workability. The hot rolling process produces a characteristic mill scale surface (dark blue-grey oxide layer) that provides temporary atmospheric corrosion protection during storage and transport, and is typically removed before painting, galvanising or machining.
Key mechanical properties at room temperature:
- S235JR — yield strength ≥235 MPa, tensile strength 360–510 MPa, elongation ≥26% (for thicknesses ≤40 mm), hardness approximately 120 HB
- S355J2 — yield strength ≥355 MPa, tensile strength 470–630 MPa, elongation ≥22% (for thicknesses ≤40 mm), hardness approximately 160 HB
Both grades are classified as fully weldable structural steels. Standard welding procedures per EN 1011-2 apply. The carbon content (max. 0.20% for S235JR, max. 0.22% for S355J2) ensures that no special precautions are required for most joint configurations in typical square bar dimensions. Filler metals should match the base material strength class — E42 electrodes for S235JR, E50 for S355J2.
Square bars can be drilled, tapped, sawn, milled, turned, flame-cut, plasma-cut and ground using standard workshop equipment. The material is suitable for hot-dip galvanising per ISO 1461, powder coating, paint systems per ISO 12944, and electroplating (zinc or nickel). Physical properties: thermal expansion coefficient approximately 12 × 10⁻⁶ /K, density 7,850 kg/m³, modulus of elasticity 210,000 MPa.
Quality and Certification
As an EN 1090 certified steel distributor with ISO 3834-2 quality management, ULAMEX ensures full compliance with European construction product regulations. Every square bar delivery can be accompanied by a mill test certificate 3.1 per EN 10204, documenting chemical composition, mechanical test results and heat traceability — please specify when placing your order.
Our quality assurance covers incoming goods inspection, proper storage conditions to prevent corrosion and mechanical damage, and complete lot traceability from mill to delivery. CE marking per Construction Products Regulation (EU) 305/2011 applies to all structural steel products supplied. Material certificates for cold-drawn bright bars include additional dimensional inspection data confirming tolerance class compliance.
Ordering and Delivery
ULAMEX maintains permanent warehouse stock of steel square bars in all standard sizes from 8 mm to 100 mm in both S235JR and S355J2 grades. Standard stock length is 6,000 mm. Cut-to-size sawing is available for projects requiring non-standard lengths. Cold-drawn bright square bars in tolerance classes h11 and h9 are available from stock or on short lead times.
As a steel bar wholesale supplier with over 35 years of experience in the European steel market, we offer competitive wholesale pricing for project quantities and frame contracts. Delivery is available across Europe, with particularly fast transit times to the DACH region (Germany, Austria, Switzerland), United Kingdom, Scandinavia, and Benelux countries.
Whether you need a single bundle of 20 mm square bars for a workshop project or a full truckload of 50 mm bars for series production, ULAMEX provides reliable supply with consistent quality and complete documentation.
Browse our full steel rods and bars catalogue including round bars, flat bars, hexagonal bars and wire rod, or contact our sales team for a tailored quotation on square bars for your project.