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Help CenterSteel Round Bar & Solid Round Steel，Q235B、Q355B、45#、20#、40Cr、42CrMo、Cr12MoV、SS400
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1. Product Overview
Round steel bar refers to solid long steel products with a perfectly circular cross-section, which are universal basic industrial profiles. Featuring uniform stress bearing capacity and superior performance in cutting, welding and forging, they are widely applied in construction, machinery manufacturing, automobile industry, heavy industry, mold production, pipe blanks and other industries. Our company supplies three types of round bars produced via hot rolling, cold drawing and forging, with complete material grades and full range of specifications. Custom cutting and heat treatment services are available. Goods are shipped from Tianjin Port, and in-stock products can be delivered within 5–7 working days.
2. Applicable Production Standards
Domestic GB Standards
GB/T 702-2017 Dimensions, shape, mass and tolerances of hot-rolled steel bars
GB/T 905 Cold-drawn steel bars – Dimensions and tolerances
GB/T 699 Quality carbon structural steel
GB/T 3077 Alloy structural steel
GB/T 1499.1 Plain steel bars for construction reinforcement
International General Standards
ASTM A36, A108, SAE1010/1045; EN 10060, DIN 10278, JIS G4051. Mill test certificates, SGS, CE, ISO inspection reports for corresponding materials can be provided upon request.
3. Product Classification by Production Process
3.1 Hot Rolled Round Bar
Diameter range: Φ5.5mm ~ Φ500mm
Surface: Black oxidized surface with native oxide scale, cost-effective
Standard length: 4–12 meters random length, custom fixed length from 1m to 12m available
Advantages: Mass production, sufficient inventory, suitable for rough machining, structural construction and seamless tube blanks
Applications: Anchor bolts, building embedded parts, general shaft components, tube blanks
3.2 Cold Drawn Round Bar
Diameter range: Φ3mm ~ Φ120mm
Surface: Bright and oxide-free with high dimensional accuracy and straightness
Tolerance: Outer diameter tolerance up to h9/h11, no secondary precision turning required
Length: 3–6 meters, short-length cutting service supported
Advantages: Smooth surface and small machining allowance, ideal for mass processing on automatic lathes
Applications: Precision pin shafts, standard fasteners, hydraulic piston rods, small precision mechanical fittings
3.3 Forged Round Bar
Diameter range: Φ120mm ~ Φ800mm extra-large specifications
Process: High-temperature forging to achieve dense internal metal structure without looseness or pores
Advantages: High strength, excellent impact resistance, qualified ultrasonic testing with minimal internal defects
Applications: Heavy-duty spindles, wind power accessories, high-pressure oil cylinders, rough blanks for large molds
4. Main Material Grades, Properties and Applications
4.1 Carbon Steel Round Bar
Low-carbon steel (Q235B / Q345B / 10# / 20#) Good plasticity, weldability and toughness with moderate tensile strength; used for building supports, anchor bolts, chains, general welded structural parts and small stamping components.
Medium-carbon steel (35# / 45#, the most widely used grade on market) Balanced comprehensive mechanical properties after quenching and tempering; applicable to machine tool spindles, gear blanks, transmission shafts, fasteners and general mechanical parts.
High-carbon steel (65Mn / T8 / T10) High hardness and elasticity; suitable for springs, shock absorption components, hand tools and small wear-resistant fittings.
4.2 Alloy Structural Round Bar for Heavy Loads
40Cr: Wear-resistant after tempering, used for automobile half shafts, gears and high-strength bolts
35CrMo / 42CrMo: High temperature resistance and impact resistance, for heavy-duty machine tools, hydraulic spindles and wind power components
20CrMnTi: Special for carburizing, applied to precision gearboxes
GCr15: Bearing steel, for wear-resistant bearing rollers and bushings
5. Specification Parameters
5.1 Diameter Sizes
Hot rolled: 5.5, 6, 8, 10, 12, 14, 16, 18, 20, 22, 25, 28, 30, 35, 40, 45, 50, 60, 80–500mm Cold drawn: 3, 4, 5, 6, 7, 8, 9, 10, 12, 14–120mm
5.2 Theoretical Weight Calculation Formula
Weight per meter (kg/m) = Diameter (mm) × Diameter (mm) × 0.00617 (steel density: 7.85g/cm³)
5.3 Custom Lengths
Standard random length: 4–12m; custom fixed lengths including 2m/3m/6m/9m/12m are acceptable; short material proportion ≤10%, free cutting service available.
5.4 Optional Surface Treatments
Hot rolled black surface, cold drawn bright surface, peeled & turned surface, polished surface, anti-rust oil coating, galvanization, VCI anti-rust paper packaging.
6. Core Product Advantages
Stable mechanical performance under load: Symmetrical circular cross-section delivers consistent mechanical properties in all directions, excellent fatigue resistance under alternating loads without stress concentration, extending service life of rotary and shaft parts.
High compatibility for machining: Perfect for turning, milling, grinding, drilling, forging, welding and heat treatment with low tool consumption during mass production.
Ample material inventory: Over 20,000 tons of spot goods including full series of carbon steel, alloy steel and stainless steel; customized special grades can be produced quickly.
Controllable dimensional precision: Strict outer diameter tolerance for cold drawn bars to reduce customers’ secondary processing costs.
Full quality traceability: Each batch is attached with heat number, material certificate and mechanical performance report; third-party SGS ultrasonic inspection and spectrum composition testing are supported.
7. Packaging, Marking & Logistics
7.1 Export Packaging Standards
Diameter ≤Φ32mm: Bundled with steel strips, 1–3 tons per bundle, wrapped with outer waterproof plastic film
Large-diameter round bars: Bundled in single or multiple pieces with protective labels attached to both ends
Fumigated export packaging: Wooden pallets + anti-rust oil + VCI volatile anti-rust paper to prevent rust and moisture during sea transportation
7.2 Marking Content
Each bundle is tagged with material grade, diameter, length, heat batch number, net weight and enterprise logo.
7. Delivery Information
Ports of loading: Tianjin Port, Qingdao Port
Lead time: 5–7 days for spot goods; 7–15 days for customized special alloys or heat-treated products
Payment term: 30% TT advance deposit, balance remitted by TT against copy of bill of lading; Letter of Credit (LC) is not acceptable
Trade terms: FOB, CIF, CFR, EXW are all negotiable
8. Main Application Fields
Construction engineering: Plain reinforcement bars, embedded anchor bolts, steel structure supports, guardrail bars
General machinery: Various transmission shafts, gear blanks, pin shafts, flange blanks, pump and valve shafts
Automobile manufacturing: Half shafts, gearbox gears, chassis fasteners, shock absorption springs
Heavy industry & wind power: Large spindles, hydraulic oil cylinders, fan transmission components
Pipeline industry: Seamless steel tube blanks, drill pipe base materials
Precision processing: Standard fasteners for automatic lathes, mold ejector pins, small precision shafts
Chemical anti-corrosion: 304/316 stainless steel anti-corrosion equipment shafts, seawater treatment accessories
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