Carbon Steel Round Bar
Carbon steel round bar is one of the most versatile and widely consumed long products in the metals industry. Used as raw material for shafts, bolts, nuts, gears, axles, pins, and countless machined components, round bar is produced by hot rolling, forging, or cold drawing to meet diverse mechanical and dimensional requirements. Huaxia-Steel supplies carbon steel round bar in diameters from 5 mm to 300 mm in grades ranging from low-carbon Q235B and S235JR to medium-carbon C45, SAE 1045, and alloy-enhanced 42CrMo4, all backed by EN 10204 3.1 mill test certificates.
Product Specifications
| Parameter | Hot-Rolled Round Bar | Cold-Drawn Round Bar | Forged Round Bar |
|---|---|---|---|
| Diameter range | 5.5 mm – 300 mm | 3 mm – 100 mm | 80 mm – 800 mm |
| Length | 4,000 – 12,000 mm | 3,000 – 6,000 mm | 3,000 – 10,000 mm |
| Diameter tolerance | ±0.30 mm (≤ 25 mm), ±0.40 mm (25 – 50 mm), ±1 % (> 50 mm) | h9 or h11 (ISO 286) | +3 / –1 mm |
| Straightness | ≤ 3 mm per 1,000 mm | ≤ 1 mm per 1,000 mm | ≤ 4 mm per 1,000 mm |
| Surface finish | Black scale (as rolled), peeled, or rough turned | Bright polished, cold drawn | Black forged, rough machined |
| Roundness | ≤ 50 % of diameter tolerance | ≤ 25 % of diameter tolerance | ≤ 75 % of diameter tolerance |
Available Grades and Standards
| Standard | Grade | Min Yield (MPa) | Min Tensile (MPa) | Typical Application |
|---|---|---|---|---|
| EN 10025-2 | S235JR (1.0038) | 235 | 360 – 510 | General structural, pins, brackets |
| EN 10025-2 | S275JR (1.0044) | 275 | 410 – 560 | Machine frames, shafts, tie rods |
| EN 10025-2 | S355JR (1.0045) | 355 | 470 – 630 | Heavy shafts, gears, high-stress parts |
| EN 10083-2 | C45 (1.0503) | 305 | 570 – 700 | Axles, crankshafts, hydraulic rams |
| DIN 17200 | CK45 (1.1191) | 305 | 570 – 700 | Turned parts, piston rods, spindles |
| ASTM A29 | SAE 1045 | 310 | 570 – 700 | Shafts, bolts, gears, king pins |
| ASTM A29 | SAE 1020 | 245 | 420 – 550 | Low-stress pins, studs, general hardware |
| GB/T 699 | 45# steel | 355 | 600 | Chinese domestic machinery |
| GB/T 1591 | Q345B | 345 | 470 – 630 | Construction, bridges, cranes |
| EN 10083-1 | 42CrMo4 (1.7225) | 650 (Q+T) | 900 – 1,100 | High-strength shafts, gears, bolts |
Manufacturing Process
Hot rolling: Billets are reheated to 1,150 – 1,250 °C and rolled through a sequence of grooved rolls to reduce diameter and achieve the required cross-section. Hot-rolled bars are supplied in the as-rolled (+AR) or normalized (+N) condition.
Cold drawing: Hot-rolled bars are pickled, coated with lubricant, and drawn through a tungsten carbide die at room temperature. Cold drawing increases yield strength by 15–30 %, improves surface finish, and achieves tight dimensional tolerances (h9 or h11).
Peeled and polished: Hot-rolled bars are turned on a peeling lathe to remove surface decarburization and scale, then polished to a bright finish. This delivers the dimensional accuracy of cold-drawn bar in larger diameters where cold drawing is impractical.
Forging: Large diameters (above 250 mm) are produced by open-die forging on hydraulic presses. Forging refines grain structure and eliminates casting defects found in continuously cast billets.
Applications
- Automotive: Axle shafts, drive shafts, steering columns, gear blanks, and fasteners.
- Machinery: Spindle shafts, pump shafts, conveyor rollers, hydraulic cylinder rods, and linear shafts.
- Construction: Anchor bolts, tie rods, dowel bars, and structural connectors.
- Railway: Axles, coupling rods, and suspension components.
- Oil and gas: Drill collar blanks, wellhead studs, and flange bolts.
- Agriculture: Plow bolts, disc harrow axles, and tractor components.
- General hardware: Nuts, bolts, screws, studs, and threaded rod.
Quality Assurance
- EN 10204 3.1 mill test certificate as standard; EN 10204 3.2 with third-party witness available.
- Chemical analysis by optical emission spectrometry (OES) on each heat.
- Mechanical testing: tensile test, hardness test, and impact test (when specified) on each batch.
- Ultrasonic testing (UT) for diameters ≥ 50 mm to detect internal defects such as pipes, inclusions, and cracks.
- Dimensional inspection: diameter, length, straightness, roundness, and chamfer.
- Surface inspection: visual check for seams, laps, cracks, and scale.
- Optional: normalizing, quenching and tempering, induction hardening, and chrome plating.
Packaging and Shipping
- Bars are bundled with steel strapping at 1.5-meter intervals.
- Bundles are wrapped in oiled paper and VCI film for corrosion protection.
- Wooden crates or steel frames for small-diameter bars to prevent bending during handling.
- End protectors (plastic caps) on precision cold-drawn bars to prevent damage.
- Container loading with proper dunnage and lashing; heavy bundles secured with timber chocks.
- Shipping marks: grade, heat number, diameter, quantity, gross/net weight, and destination.
Request a quotation for carbon steel round bar. Specify diameter, length, grade, delivery condition (hot rolled, normalized, cold drawn, Q+T), and any secondary processing (peeling, polishing, cutting, threading). Huaxia-Steel supplies bars from 5 mm to 300 mm diameter with full traceability. Contact us for pricing and lead time.
