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Help CenterSteel Round Bar & Round Steel Bar，Q235A/Q235B、HPB300、Q355B/C/D、Q460C、S355J2、10#、20#、35#、45#（S45C）、50#、60#、70Mn
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1. Product Overview
Solid steel round bar refers to long steel products with solid circular cross-section, which are divided into three major categories: hot rolled round bar, cold drawn bright bar (silver bright steel) and forged round bar. Featuring stable strength and excellent processability with complete specifications, they are widely applied in construction, machinery, automobile, wind power, mold, steel structure engineering and other fields. Our company supplies a full range of round bars including plain carbon steel, low alloy steel, high-quality carbon structural steel, alloy structural steel and bearing steel.
2. Executive Standards
Domestic GB Standards
Dimensions of hot rolled round bars: GB/T 702-2017 (Φ6–310mm)
Cold drawn bright bars: GB/T 905, GB/T 3207-2025
High-quality carbon structural steel: GB/T 699
Alloy structural steel: GB/T 3077
High-strength low alloy steel: GB/T 1591
Plain round reinforcing steel bar: GB 1499.1-2024
International Standards
EN10025, ASTM A36/A572/1045, SAE series, JIS Japanese standards. Mill Test Certificate (MTC) corresponding to specified materials can be issued.
3. Classification of Material Grades
3.1 Plain Carbon Steel Round Bar (General Construction Use)
Grades: Q235A/Q235B, HPB300 (plain round reinforcing bar)Features: Easy to weld with high cost performance; used for factory supports, embedded parts, guardrails and raw materials of bolts.
3.2 High-strength Low Alloy Round Bar (Load-bearing Structure)
Grades: Q355B/C/D, Q460C, S355J2Features: Excellent low-temperature impact resistance and strong bearing capacity; applied to bridges, wind power base plates and girders of engineering machinery.
3.3 High-quality Carbon Structural Steel (Main Material for Machining)
Grades: 10#, 20#, 35#, 45# (S45C), 50#, 60#, 70Mn45# round bar is the most widely used type. It features moderate hardness after quenching and tempering, suitable for shafts, gears, mold ejector pins and flange blanks.
3.4 Alloy Structural Round Bar (High-strength & Wear-resistant Components)
Grades: 20Cr, 40Cr, 42CrMo, 20CrMnTi, 40CrNiMo
42CrMo: Wind power main shafts, hydraulic piston rods and heavy-duty gears
20CrMnTi: Automobile transmission gears
3.5 Special Round Bar (Customized on Demand)
Bearing steel GCr15, free-cutting steel, spring steel, forged large-diameter round bar (Φ135–400mm)
4. Specification Parameters
4.1 Diameter Range
Hot rolled black round bar: Φ6mm ~ Φ310mm
Cold drawn bright bar / silver bright steel: Φ3mm ~ Φ80mm (dimensional tolerance ±0.02~0.1mm, smooth surface without secondary polishing)
Forged large round bar: Φ135mm ~ Φ400mm
4.2 Standard Length
Standard fixed lengths: 6m, 9m, 12m; customized lengths ranging from 1m to 12m are available, with short-length proportion ≤10%.
4.3 Surface Treatment
Hot Rolled Black Round Bar: Covered with black oxide scale, low cost, preferred for rough machining
Cold Drawn Bright Bar / Peeled Bar: Bright surface without oxide scale, precise tolerance for direct finish machining
Ground Round Bar: Mirror polishing surface, used for precision shafts and piston rods
Optional surface treatment: Galvanizing, anti-rust oil coating, VCI anti-rust film packaging
4.4 Dimensional Tolerance
Hot rolled: Standard grade and high-precision grade negotiable
Cold drawn silver bright bar: h9/h8/h7 precise tolerance, compatible with automatic CNC machining
5. Core Product Advantages
Stable material performance: Raw materials from formal steel mills with traceable heat numbers; MTC containing chemical composition and mechanical properties provided for each batch.
Balanced processability: Low-carbon grades for easy welding, medium-carbon grades available for quenching & tempering, alloy steel with wear resistance and impact resistance.
Complete size coverage: One-stop supply including small-diameter wire rods, medium-diameter straight bars and extra-large forged round bars.
Straightness compliance: Free of obvious bending, cracks, scars, inclusions and other surface defects.
Flexible delivery: Spot goods in stock; small cutting orders and bulk full-bundle orders are both acceptable. Loading can be arranged at Tianjin Port within 5-7 days.
Export-specific packaging: Moisture-proof and anti-rust, suitable for ocean transportation to avoid collision damage.
6. Main Application Fields
Construction Engineering: Factory steel structures, bridge embedded parts, pile foundations, foundation bolts, guardrail supports
General Machinery: Transmission shafts, gears, flanges, lead screws, fixtures, pump and valve blanks
Automobile Manufacturing: Transmission gears, semi-axles, suspension parts, engine shaft components
Wind Power Energy: Wind turbine main shafts, gear box forgings, base connecting shafts (specialized 42CrMo)
Mold Tooling: Mold blanks, ejector pins and guide posts made of 45# and Cr series steel
Engineering Machinery: Load-bearing pins and hydraulic components for excavators and cranes
Hardware Fasteners: Raw materials for bolts, nuts and rivets
7. Delivery Condition
As-hot-rolled (main supply state): Naturally cooled after rolling without extra heat treatment
Annealed state: Reduced hardness for convenient deep drilling and turning
Quenched & tempered state (quenching + high-temperature tempering): Directly usable finished products to save customers’ heat treatment procedures
Normalizing, solution treatment and other special heat treatments can be customized per customer’s technical agreement.
8. Inspection Standards
Dimensional inspection: Full inspection of diameter, length, ovality and straightness
Physical and chemical test: Spectrum analysis of chemical composition, tensile strength, yield strength, elongation, hardness and low-temperature impact test
Optional Non-Destructive Testing (NDT): UT ultrasonic testing, MT magnetic particle testing (available for high-end wind power and pressure vessel orders)
English version Mill Test Certificate is issued for each batch for customs clearance.
9. Packaging & Ocean Shipment
Standard bundled packing: Round bars with diameter ≤180mm bundled with plastic-coated steel straps, 2-3 tons per bundle, labeled in both Chinese and English (specification, material grade, heat number, weight)
Precision bright bars: Wrapped with anti-rust paper and VCI film internally, packed on wooden pallets or wooden cases externally to prevent scratch and rust.
Export standard: Moisture-proof and rain-proof packaging, suitable for sea transportation via 20GP/40GP containers.
Loading Port: Tianjin Port; loading and container arrangement within 5-7 working days after production completion.
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