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Help CenterFlat Steel & Flat Bar，EN 10025、ASTM A36/A572、JIS G3101、ISO 630、Q355B / S355JR / A572 Gr50、10#、20#、45# 、40Cr、42CrMo
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1. Product Overview
Flat Bar (commonly called flat iron) is long strip section steel with rectangular cross-section and rounded edges, divided into four categories: hot rolled flat bar, cold drawn precision flat bar, hot-dip galvanized flat bar and forged flat bar. Manufactured from carbon steel and low alloy steel via high-temperature hot rolling or room-temperature cold drawing, it features flat section, large contact surface and convenient welding & bending processing with stable mechanical properties. It can be directly used in steel structures, earthing lightning protection, mechanical processing, photovoltaic brackets, guardrail embedded parts and other engineering projects. Compliant with domestic special section steel standards and mainstream European, American & Japanese export industrial standards, custom processing including fixed-length cutting, punching, bending and galvanizing is available.
Applicable Standards
Domestic StandardsGB/T 704-2016 Dimensions, Shape, Mass and Permissible Deviations of Hot Rolled Steel Bars, YB/T 037 Cold Drawn Flat Bars, GB/T 700 Carbon Structural Steel, GB/T 1591 High Strength Low Alloy Structural Steel, GB/T 13912 Technical Specifications for Hot-Dip Galvanized Coatings
International Export StandardsEN 10025, ASTM A36/A572, JIS G3101, ISO 630
2. Main Steel Grades & Application Conditions
Q235B / S235JR / A36 (General Carbon Steel)Excellent plasticity and weldability with cost advantage, for building steel structures, guardrails, embedded plates, general machine bases and indoor supports
Q355B / S355JR / A572 Gr50 (HSLA Steel)High yield strength and outstanding low-temperature toughness, for photovoltaic brackets, bridge fittings, construction machinery load-bearing parts and outdoor heavy-duty structures
10#, 20#, 45# High Quality Carbon Steel (Cold Drawn Precision Flat Bar)Ultra-high dimensional accuracy, for machined shaft seats, mold accessories, machine tool guide rails and precision equipment parts
40Cr, 42CrMo Alloy Flat BarSuperior wear resistance and tensile strength, for heavy machinery, transmission components and heavy-duty forged parts
3. Product Classification by Manufacturing Process
Hot Rolled Flat Bar (Main Stock Product)Formed under 1200℃ high temperature rolling, black mill scale or sandblasted surface, regular dimensional tolerance, low cost, preferred material for general structural engineering
Cold Drawn Precision Flat BarMulti-pass cold drawing at room temperature, high precision & oxide-free smooth surface without secondary polishing, dedicated for precision machinery
Hot-Dip Galvanized Flat BarHot rolled substrate fully hot-dip galvanized with uniform & firmly bonded zinc layer, for power earthing, lightning protection, outdoor anti-corrosion brackets and coastal projects
Forged Flat BarHigh-temperature forging with dense internal structure free of lamination, superior impact & compression resistance, for heavy-load mining & mechanical equipment parts
4. Complete Production Process
Hot Rolled Flat Bar Process
Steel billet heating → Reciprocating hot rolling → Sizing & straightening → Cooling → Cutting to fixed length → Surface cleaning → Dimension & appearance inspection → Marking & coding → Bundling with steel strips & warehousing
Cold Drawn Flat Bar Process
Pickling & phosphating of hot rolled blank → Multi-pass cold drawing for thickness reduction → Stress relief annealing → Finishing & straightening → Polishing & deburring → Full dimensional inspection → Anti-rust packaging
Galvanized Flat Bar Process
Degreasing & pickling of finished flat bar → Flux dipping & wetting → Hot-dip galvanizing at 460~520℃ → Air blowing to remove excess zinc → Passivation anti-rust treatment → Inspection & packing
5. Core Specification & Technical Parameters
Dimension RangeWidth: 12mm～300mm; Thickness: 3mm～60mm; Common sizes: 20×3, 40×4, 50×5, 80×8, 100×10mm
Standard Fixed Length: 6m, 9m, 12m, customized cutting length 0.5–15m available
Dimensional Tolerance
Hot Rolled Flat Bar: Thickness ±0.3~0.8mm, Width ±1.0mm, Straightness ≤2mm/m
Cold Drawn Precision Flat Bar: Thickness ±0.02~0.15mm, Width ±0.2mm, Straightness ≤0.8mm/m
Zinc Coating Index (Galvanized Flat Bar)Zinc coating weight ≥120g/㎡, pass neutral salt spray test ≥800h without peeling or missing plating
Mechanical Performance
Q235B: Yield strength ≥235MPa, tensile strength 375–500MPa, no cracking after 180° cold bending
Q355B: Yield strength ≥355MPa, qualified low-temperature impact property for severe cold outdoor environments
Surface OptionsHot rolled black finish, sandblasted rust removal, bright cold drawn, silver-gray hot-dip galvanized, polished bright surface
6. Core Product Advantages
Convenient forming & excellent weldabilityFlat rectangular cross-section ensures tight joint fitting, no cracking during electric welding & gas cutting, supports direct bending, punching, drilling and stamping without secondary milling process.
Complete specifications for diversified demandsSufficient spot stock of standard hot rolled bars, customized special specifications including precision cold drawn, galvanized and forged bars, covering simple civil structures and heavy industrial equipment.
Complete anti-corrosion system for long outdoor service lifeZinc layer provides cathodic protection for galvanized flat bars, resisting rust in buried, open-air and coastal high-corrosion environments, standard section dedicated for earthing & lightning protection projects.
Standard & accurate weight calculationUniform theoretical weight formula (kg/m = Width(mm) × Thickness(mm) × 0.00785), convenient for engineering budget and blanking calculation.
Stable mechanical performance with high safety factorRolling & forging eliminates internal defects such as lamination and pores, uniform mechanical property along full length, superior load-bearing & impact resistance compared with simply cut steel plates.
Sufficient Stock & Stable Delivery CycleFull series of materials and specifications in stock, shipped directly from Tianjin Port, production & delivery cycle 5–7 days. One-stop custom processing including punching, bending, galvanizing and fixed-length cutting available for bulk orders.
7. Main Application Fields
Power Lightning & Earthing: Hot-dip galvanized earthing flat bars and lightning down conductors for substations, buildings and photovoltaic power stations
Steel Structure Engineering: Factory supports, embedded parts, stair treads, guardrails and curtain wall connectors
New Energy Photovoltaic: Main & secondary beams of photovoltaic brackets, fixed bases and outdoor anti-corrosion supports
Machinery Manufacturing: Equipment bases, machine tool guide rails, gear blanks, agricultural machinery frames and forklift fittings
Municipal Transportation: Road guardrails, bridge reinforcement parts, lamp post bases and traffic sign brackets
Construction Machinery: Load-bearing structures, wear-resistant base plates and trailer girders for excavators & loaders
Building & Decoration: Metal door frames, stair handrails, ceiling keels and decorative metal components
8. Factory Inspection & Complete Qualification Documents
Full-item inspection for every piece per batch with complete export supporting documents attached:
Full dimensional inspection of width, thickness, length, straightness and appearance
Mechanical performance test including tensile and cold bending, room-temperature impact test
Additional zinc coating weight, adhesion and salt spray anti-corrosion test for galvanized flat bars
Spectral chemical composition analysis to avoid material mismatch
Original Mill Test Certificate EN 10204 3.1, factory certificate, SGS third-party inspection report, CE certification documents
9. Packaging, Marking & Logistics Delivery
Packaging: Same specifications bundled uniformly with steel strips, metal corner protectors to prevent collision damage; export goods wrapped with waterproof plastic film and fixed on wooden pallets for sea transportation moisture & rust resistance
Marking: Permanent printing on side of each bundle including material grade, width × thickness, length, heat number, execution standard and manufacturer; product qualification label attached to each bundle
Delivery: Direct shipment from warehouse to Tianjin Port, suitable for 20GP/40HQ full containers and bulk carriers; delivery cycle 5–7 days, FOB/CIF/CFR trade terms acceptable, full container & LCL export supported
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