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Carbon Steel Round Bar
What Are Carbon Steel Round Bars?
Carbon steel round bars are long, solid cylindrical products manufactured from carbon steel through hot rolling, cold rolling, or forging processes?
Unlike hollow sections such as pipes or tubes, round bars are solid throughout, providing maximum strength and material density for applications requiring high load-bearing capacity and durability.
The key advantages of carbon steel round bars include:
High Strength: Excellent tensile and yield strength for structural and mechanical applications
Cost-Effective: More affordable than alloy or stainless steel, ideal for mass production
Excellent Machinability: Easy to cut, turn, drill, and thread into precision components
Versatility: Available in various carbon content grades for different performance requirements
100% Recyclable: Environmentally sustainable material
Key Specifications (Customizable for Your Production & Project Needs)
We provide standard specifications complying with international standards (ASTM, EN, GB, JIS) and support full customization to match your production equipment, processing requirements, and project scenarios. The following are the common specifications most carbon steel round bar buyers choose, covering mainstream application scenarios:
| Item | Specification Range | Common Standards | Buyer-Focused Note |
| Diameter | 5mm - 200mm (common), up to 500mm (customized) | ASTM A108, EN 10083, GB/T 702, JIS G3401 | Diameter tolerance ≤ ±0.05mm, ensuring uniform machining and dimensional consistency |
| Length | 3m - 12m (standard), customizable (cut to length) | ASTM A108, EN 10083, GB/T 702, JIS G3401 | Cut-to-length service to reduce on-site cutting waste and processing time |
| Temper State | Annealed (O), Normalized (N), Quenched & Tempered (QT) | International Trade Standard | Customizable temper to match your machining and strength requirements |
| Surface Treatment | Mill Finish, Pickled, Polished, Hot-Dip Galvanized | International Trade Standard | Polished for precision parts; galvanized for anti-rust in harsh environments |
Precision Dimensional Specifications (Your Efficiency)
| Parameter | Hot Rolled (HR) | Cold Drawn / Cold Finished (CD/CF) | Turned & Ground (TG&P) |
| Diameter Range | 10 – 500 mm | 3 – 150 mm | 6 – 300 mm |
| Diameter Tolerance | ASTM A29 / EN 10060 (typical ±0.5 mm to ±2.0 mm depending on size) | ASTM A108 (typical h8 to h11, ±0.03 mm to ±0.10 mm) | Precision (typically ±0.025 mm / 0.001") |
| Length | 3– 12 m (random or fixed) | 3– 6 m (random or fixed) | 3 – 6 m (random or fixed) |
| Straightness | Standard commercial straightness | 1 mm per 1000 mm typical | Precision straightness available |
| Surface Finish | As-rolled (with scale) | Smooth, bright, scale-free | Polished, precision surface |
Primary Applications Across Industries
Carbon steel round bars serve critical functions across diverse sectors due to their versatility and mechanical properties| Industry | Key Applications | Recommended Grades | Material Requirements |
| Automotive | Drive shafts, axles, steering components, transmission parts, gears, connecting rods | 45#/1045, 40Cr, 42CrMo | High fatigue resistance, precise tolerances, heat treatability |
| Construction & Infrastructure | Concrete reinforcement, scaffolding, structural supports, anchors, dowels, bolts | Q235B, Q355B, A36 | Weldability, yield strength, cost-effectiveness |
| Heavy Machinery & Equipment | Shafts, spindles, rollers, hydraulic piston rods, machine tool spindles, crane components | 45#/1045, 42CrMo, 40Cr | Wear resistance, machinability, high strength |
| Industrial Manufacturing | Conveyor rollers, pulleys, fasteners, couplings, bushings, pins, studs | 20#/1020, 35#, 45#/1045 | Consistent machinability, dimensional accuracy |
| Forging Industry | Raw material for forged components: crankshafts, connecting rods, gear blanks, flanges | 45#/1045, 40Cr, 42CrMo | Clean internal structure, forgeability |
| Oil & Gas | Valve components, pump shafts, drilling equipment parts, wellhead components | 42CrMo, 4140, 1045 | Toughness, fatigue resistance, traceability |
| Agriculture | Tractor components, plowshares, harvester parts, implement shafts | 45#/1045, Q355B | Durability, impact resistance |
| Mining | Wear-resistant parts, crusher components, conveyor shafts | High-carbon, alloy grades | Surface hardness, wear resistance |
FAQ (For Carbon Steel Round Bar Buyers)
Q1: What are the key factors affecting the machinability of carbon steel round bars, and how do you ensure they meet our processing requirements?
A1: The machinability of carbon steel round bars is mainly determined by carbon content, temper state, and surface roughness. For low-carbon grades (e.g., ASTM A108 Gr.1010), we adopt full annealing (O temper) to improve ductility and reduce machining resistance; for medium-carbon grades (e.g., ASTM A108 Gr.1045), normalized (N) temper is used to balance strength and machinability.
We strictly control surface roughness (Ra ≤ 1.6μm for polished bars) and diameter tolerance to avoid tool wear and ensure machining precision. We also provide detailed mechanical property reports (tensile strength, hardness, elongation) to confirm compatibility with your turning, milling, and drilling equipment.
Q2: What quality inspection standards do your carbon steel round bars comply with, and what certificates can you provide for international trade?
A2: Our carbon steel round bars fully comply with international standards such as ASTM A108, EN 10083, GB/T 702, and JIS G3401. Each batch of products undergoes strict quality inspection, including chemical composition analysis (via spectral analysis), dimensional accuracy detection, surface defect inspection, and mechanical property testing (hardness, tensile strength, yield strength).
We provide MTC (Material Test Certificate) in accordance with EN 10204 3.1/3.2 standards as standard. Additionally, we can provide ISO 9001, CE (for European markets), and SGS/CCIC third-party inspection reports upon your request to meet customs clearance and project acceptance requirements.
Q3: How do you prevent carbon steel round bars from rusting, scratching, or being deformed during transportation and storage?
A3: We adopt professional packaging and protection measures: each round bar is wrapped with PE moisture-proof film and kraft paper to prevent rust and scratches; for small-diameter bars, we bundle them with steel tape and place them on wooden pallets to avoid deformation.
For sea transportation, we add waterproof covers, desiccants, and anti-collision buffers to prevent salt spray and moisture erosion. We also mark "Handle with Care", "Moisture-Proof", and "Anti-Collision" on the packaging to ensure the bars arrive in intact condition and can be directly processed.
Q4: What is the difference between hot-rolled and cold-drawn carbon steel round bars, and how should we choose based on our application?
A4: Hot-rolled carbon steel round bars (produced at 1000℃+ ) have higher diameter tolerance, good toughness, and lower cost, suitable for general structural parts, fasteners, and low-precision machining.
Cold-drawn carbon steel round bars (produced at room temperature) have higher dimensional accuracy, smoother surface, and better mechanical properties, suitable for precision components (e.g., shafts, gears) and applications requiring high machining precision. We can recommend the most suitable type based on your machining requirements, product precision, and cost budget.
Q5: For bulk orders, what is your lead time, and how do you ensure on-time delivery for our project schedule?
A5: For standard specifications and grades (in stock), the lead time is 5-7 working days. For customized specifications (non-standard diameter, length, temper state, or surface treatment) or bulk orders (≥50 tons), the lead time is 12-20 working days, depending on the production schedule.
We have a dedicated production scheduling team to track progress in real time, and cooperate with professional international logistics companies to choose the optimal shipping route. We will provide you with a detailed delivery schedule and real-time logistics updates to ensure the bars arrive on time to match your project or production plan.
Q6: Can you provide customized processing services (e.g., cutting, threading, grinding) for carbon steel round bars, and what are the relevant specifications?
A6: Yes. We provide professional customized processing services to match your installation and processing needs. Cutting length can be adjusted from 1m to 12m, with a tolerance of ±0.5mm; threading (BSP, NPT standard) is available for bars with diameter 10mm-100mm; grinding can be customized to achieve surface roughness Ra ≤ 0.8μm for precision parts.
All processing is completed by automatic equipment to ensure precision and consistency, reducing your on-site processing time and costs.
Contact our sales team today for a quotation or to discuss your project requirements. We are committed to providing high-quality carbon steel bar that meet your exact specifications and delivery deadlines.
Your trusted partner in carbon steel solutions.For further technical information, pricing, or customization, please contact our sales team:
Tel/WA/Wechat: +86 13225105678
Email: sales01@duohessplate.com
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