Steel round bars, also referred to as smooth bars or steel rods, are fundamental products for construction, mechanical engineering and general fabrication throughout Europe. ULAMEX supplies hot rolled round bar steel in diameters from 6 mm to 250 mm, manufactured from non-alloy structural carbon steel to full European standard compliance. For precision applications, we also offer bright drawn steel bar with h9 or h11 tolerance on request, providing the tighter dimensional control required for shafts, pins and machined components. With over 38 years of experience as a steel round bar supplier, ULAMEX maintains deep stock of the most requested round bar sizes — from 10 mm through 100 mm and beyond — ensuring rapid dispatch across the United Kingdom, Scandinavia, Benelux and the wider European market.
Material Grades and Standards for Steel Round Bars
Our steel round bars are manufactured in accordance with EN 10060, the European standard for hot rolled round steel bars covering dimensions, shape and tolerances for general-purpose applications. Material grades conform to EN 10025-2, the European reference standard for structural steels. We stock two principal grades:
- S235JR (material number 1.0038, formerly St37-2, equivalent to ASTM A36) — the most widely used mild steel round bar grade for general construction and fabrication. Minimum yield strength of 235 MPa (for diameters up to 16 mm), tensile strength of 360–510 MPa and minimum elongation of 26%. Charpy V-notch impact toughness guaranteed at 27 J at +20°C. S235JR round bar is the go-to material for general-purpose pins, dowels, spacers, handles and fabrication stock where ease of working is prioritised over high strength.
- S355J2 (material number 1.0577, formerly St52-3, equivalent to ASTM A572 Grade 50) — a higher-strength structural steel with minimum yield strength of 355 MPa, tensile strength of 470–630 MPa and guaranteed impact toughness of 27 J at −20°C. S355J2 round bar steel is specified for axles, heavily loaded pins, mechanical engineering components and applications requiring superior strength-to-weight performance, particularly in low-temperature environments.
Both grades exhibit excellent weldability with carbon equivalent values (CEV) below 0.45, compatible with MIG/MAG, MMA and TIG welding processes. For thicknesses below 25 mm, no mandatory preheat is required under standard conditions. Where full traceability is needed, we supply EN 10204 Type 3.1 inspection certificates documenting chemical composition, mechanical properties and compliance with the relevant product standard.
Dimensions, Tolerances and Specifications
ULAMEX stocks a comprehensive selection of steel round bar sizes to serve diverse project and production requirements:
- Diameter range: 6 mm to 250 mm
- Standard length: 6,000 mm (6 m)
- Surface finish: hot rolled (mill scale) as standard; bright drawn (cold finished) to h9 or h11 tolerance on request
- Most requested diameters: 8, 10, 12, 14, 16, 18, 20, 22, 25, 28, 30, 35, 40, 45, 50, 55, 60, 65, 70, 80, 90, 100, 120, 150, 200, 250 mm
Dimensional tolerances for hot rolled round bar conform to EN 10060. For diameters up to 25 mm, the tolerance is typically ±0.4 mm; for diameters 25–100 mm, tolerances widen to ±0.75 mm; for diameters above 100 mm, tolerances reach ±1.3 mm. Ovality (difference between maximum and minimum measured diameter on the same cross-section) must not exceed 75% of the diameter tolerance. Bright drawn steel bar to h9 tolerance offers significantly tighter dimensional control: for example, a 30 mm diameter bar has a tolerance of 0 / −0.052 mm, making it suitable for precision machining, bearing journals and sliding fits.
The weight per metre of a steel round bar is calculated as: diameter² × 0.006165 kg/m (for steel density 7,850 kg/m³). For example, a 20 mm round bar weighs approximately 2.47 kg/m, a 50 mm round bar weighs approximately 15.41 kg/m, and a 100 mm round bar weighs approximately 61.65 kg/m. Our team provides steel round bar weight tables and dimensional guidance on request.
Applications of Steel Round Bars
Steel round bars serve a remarkably broad range of applications, thanks to their symmetrical cross-section, consistent mechanical properties in all radial directions and straightforward machinability. Key application areas include:
- Mechanical engineering and machine building — Round bar for shafts, axles, spindles, drive pins and coupling elements. The circular cross-section provides uniform torsional resistance and is the starting material for most turned and ground rotating components. S355J2 round bar is preferred where higher fatigue strength and load-bearing capacity are required.
- Fabrication and construction — anchor bolts, threaded rods, hold-down bolts, hinge pins, dowels and structural connecting elements. Steel rod in diameters 12–30 mm is extensively used for connection hardware in steel-frame buildings, timber structures and precast concrete assemblies.
- Turning and CNC machining stock — Steel bar for machining is one of the largest demand segments. Bright drawn steel bar with h9 or h11 tolerance eliminates the need for initial roughing cuts, reducing machining time, tool wear and material waste. Applications include bushings, spacers, studs, valve stems and hydraulic cylinder rods.
- Automotive and transport — axle blanks, trailer pin stock, tow bars, suspension links and general vehicle component manufacturing. Round bar in diameters 20–60 mm accounts for the highest volume in this segment.
- Agricultural and material handling equipment — plough shafts, conveyor rollers, pivot pins, loader arm pins and general repair stock for farm machinery and warehousing systems.
- Forging and forming — hot rolled carbon steel round bar serves as feedstock for drop forging, upset forging, ring rolling and hot forming of components such as flanges, hooks, shackles and chain links.
The ability to source round bar steel in a continuous diameter range from 6 mm to 250 mm from a single supplier simplifies procurement, consolidates deliveries and reduces inventory complexity for fabricators and machine shops.
Technical Properties of Steel Round Bars
The mechanical and physical properties of our steel round bars provide the performance characteristics demanded by structural engineering, mechanical design and machining operations:
- Yield strength: 235 MPa (S235JR) or 355 MPa (S355J2) for diameters up to 16 mm
- Tensile strength: 360–510 MPa (S235JR) or 470–630 MPa (S355J2)
- Elongation at break: minimum 26% (S235JR) or 22% (S355J2)
- Density: 7,850 kg/m³
- Modulus of elasticity: 210,000 MPa (210 GPa)
- Thermal conductivity: approximately 50 W/(m·K) at 20°C
Weldability is excellent for both grades across all common arc welding processes. For hot rolled round bar up to 25 mm diameter, welding can proceed without preheat under standard ambient conditions. For larger diameters in S355J2 or multi-pass welds in restrained joints, preheating to 75–150°C may be recommended per EN 1011-2. Welded connections involving round bar — such as plug welds, fillet-welded pins or butt-welded rod extensions — should follow qualified welding procedure specifications (WPS) per EN ISO 15614-1 when the work falls under EN 1090 execution classes.
Machinability of S235JR round bar is rated at approximately 70% relative to free-cutting steel (AISI 1212 = 100%). For improved surface finish and chip control during turning, boring or milling operations, bright drawn steel bar provides a cleaner starting surface free from mill scale, reducing tool wear and enhancing dimensional accuracy of finished parts. Hot rolled round bar can be readily heat-treated (normalising, stress relieving) where application requirements dictate improved uniformity of properties or residual stress reduction.
Quality Assurance and Certification
ULAMEX operates under EN 1090-1 certified factory production control and ISO 3834-2 quality management. Every consignment of steel round bar is fully traceable to the originating mill and heat number. We provide EN 10204 Type 3.1 inspection certificates as standard for structural applications, documenting chemical analysis, tensile test results, impact test values and dimensional measurements. Our certifications underpin the reliability and compliance that fabricators, machine shops and construction companies require from their steel supply chain.
Ordering and Delivery
The most popular steel round bar sizes are held in stock for rapid availability, with standard lead times of 2–5 working days across Europe. Bright drawn steel bar in h9 and h11 tolerance is available on request with lead times from our finishing partners. For project volumes, non-standard diameters or special lengths, we offer competitive delivery schedules sourced directly from our mill network. Round bars are supplied in bundles, strapped and labelled with heat number and material grade for full traceability on site.
To request a quotation for steel round bars, bright drawn bar or any product from our black steel rods range, please contact our sales team. We offer expert technical guidance, competitive wholesale pricing and dependable logistics across the United Kingdom, Scandinavia, Benelux and the wider European market — supported by more than 35 years of experience in steel distribution.