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Help CenterFlat Steel & Flat Steel Bar，Q195、Q235B、SS400、A36、S235JR、Q355B、S355JR、A572 Gr50、45#、40Cr、42CrMo
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1. Product Overview
Flat Steel Bar (also called flat iron) is long rectangular section steel, divided into four categories: hot rolled flat bar, cold drawn bright flat bar, hot-dip galvanized flat bar and spring flat bar. Hot rolled flat bar is formed by high-temperature rolling with standard rounded edges; cold drawn flat bar is precision drawn at room temperature with ultra-tight tolerance and mirror smooth surface; galvanized flat bar with anti-corrosion coating is widely used for lightning grounding and outdoor guardrails. It can be bent, welded, punched, cut and machined, serving as universal basic section steel for steel structures, power grounding, machinery parts, bridges and iron art projects.
2. Core Product Advantages
Regular Shape & Graded Dimensional ToleranceCost-effective hot rolled grade with stable dimension; cold drawn flat bar achieves tolerance ±0.02mm for thickness & width, excellent straightness and flatness without secondary milling.
Superior Comprehensive MachinabilityLow carbon equivalent for carbon & low alloy grades, crack-free welding; suitable for 180° cold bending, stamping, drilling and tapping, matching all sheet metal & mechanical processing procedures.
Complete Anti-corrosion Solutions for All Working ConditionsMultiple options: black hot rolled finish, shot blasting anti-rust primer, electro-galvanized, hot-dip galvanized, Zn-Al-Mg coated, applicable for indoor, open-air, coastal high salt spray and chemical corrosive environments.
Full Material Grades with Various Strength LevelsComplete series covering ordinary carbon, HSLA high strength, wear-resistant alloy and dedicated spring flat bar, matching light decorative load to heavy equipment bearing load.
Full Specification Range & Custom LengthWide coverage of thickness & width; standard lengths 6m/9m/12m, custom cuttable from 0.5m to 12m to reduce customer blanking loss.
Complete Inspection & Full Export DocumentsEN10204 3.1 material certificate attached for each batch, including mechanical, chemical composition and galvanizing layer test reports, complying with inspection standards of engineering, shipyard and power station worldwide.
3. Main Executive Standards (Domestic & International Export Standards)
Domestic Standards
GB/T 704-2016 Dimensions, shape, weight and tolerances of hot rolled steel bars (hot rolled flat bar)
GB/T 905-2001 Cold drawn flat bar dimensional tolerance
GB/T 700 Carbon structural steel
GB/T 1591 High strength low alloy structural steel
GB/T 13912 Technical specification for hot-dip galvanized coating
International Export Standards
EN 10025 European structural flat bar S235JR, S355JR
ASTM A36 / A572 Gr50 US carbon & high strength flat bar
JIS G3101 SS400 Japanese general flat bar
EN 10278 European cold drawn bright flat bar
4. Product Classification & Application
Hot Rolled Black Flat Bar (Main General Grade)Q235B/Q355B, low cost & good toughness; steel structure connecting plates, embedded parts, stair treads, supports, bridge stiffeners.
Cold Drawn Bright Flat Bar (Precision Machinery Use)Oxide-free smooth surface, high dimensional accuracy; machine tool guide rails, flange blanks, automation equipment fittings, hardware stamping parts.
Hot-dip Galvanized Flat Bar (Lightning Grounding & Outdoor Anti-corrosion)Heavy zinc coating 60–280g/㎡; power lightning grounding, photovoltaic supports, municipal guardrails, dock anti-corrosion components.
Spring Flat Bar (Heavy-duty Elastic Parts)65Mn, 60Si2Mn; automobile leaf springs, construction machinery shock shrapnel, heavy-duty elastic supports.
5. Common Material Grades
Carbon Flat Bar (Construction, Grounding, General Machinery)
Q195, Q235B, SS400, A36, S235JR
HSLA High Strength Flat Bar (Bridges, Heavy Equipment, PV Supports)
Q355B, S355JR, A572 Gr50
Alloy Structural Flat Bar (Wear-resistant High-strength Machining Parts)
45#, 40Cr, 42CrMo
Spring Flat Bar (Shock Absorption & Elastic Components)
65Mn, 60Si2Mn
6. Specification Range
Thickness: 3mm–60mm
Width: 12mm–300mm
Standard Length: 6m, 9m, 12m; custom length 0.5–12m available
Theoretical Weight Formula: kg/m = Width(mm) × Thickness(mm) × 0.00785
Surface Delivery Condition: Hot rolled black finish, cold drawn bright, shot blasted primed, electro-galvanized, hot-dip galvanized
Tolerance: Hot rolled ±0.3~1.0mm; precision cold drawn ±0.02~0.15mm
7. Complete Production Process
Hot Rolled Flat Bar Flow
Slab heating → High-pressure water descaling → Universal mill rectangular section rolling → Hot straightening → Cooling & fixed-length shearing → Surface cleaning → Marking stenciling → Strapping & warehousing
Cold Drawn Bright Flat Bar Flow
Hot rolled blank → Pickling & phosphating lubrication → Multi-pass cold drawing thickness reduction → Finish polishing → Straightening → Fixed-length cutting → Anti-rust packaging
Galvanized Flat Bar Deep Processing Flow
Finished flat bar → Shot blasting rust removal → High-temperature hot-dip galvanizing → Cooling & passivation → Inspection & strapping
8. Quality Inspection Items (EN10204 3.1 Material Certificate Attached)
Dimensional Inspection: Width, thickness, length, straightness, flatness, edge radius tolerance
Surface Inspection: Full inspection for cracks, laps, scabs, scratches, oxide scale and missing galvanizing coating
Chemical Spectrum Analysis: Strictly controlled S≤0.045%, P≤0.045%
Mechanical Tests: Yield strength, tensile strength, percentage elongation, 180° cold bending test
Special Galvanizing Test (Galvanized Flat Bar): Zinc coating weight, adhesion, neutral salt spray test
Surface Roughness Test (Cold Drawn Bright Flat Bar)
9. Main Application Fields
Steel Structure ConstructionFactory beam & column connecting plates, embedded steel plates, stair treads, roof purlins, guardrails, iron gates, curtain wall frames
Power & Photovoltaic IndustryLightning grounding flat bar (standard 40×4 / 50×5 grounding specification), cable trays, tower fittings, photovoltaic support bases
General Machinery ManufacturingMachine tool bases, guide rails, flange blanks, equipment supports, agricultural machinery parts, forklift reinforcements
Transportation & Bridge EngineeringBridge stiffeners, vehicle chassis reinforcements, ship bulkhead stiffeners, highway guardrails
Chemical & Environmental Protection EquipmentPipe supports, storage tank bases, anti-corrosion equipment frames, sewage treatment structural parts
Decoration & Hardware IndustryStorage rack beams, metal furniture, balcony railings, craft iron art, indoor decorative profiles
10. Packaging & Export Logistics
Same specification stacked in layers, bundled transversely & longitudinally with steel strips, plastic end caps for edge protection; galvanized & cold drawn flat bars wrapped with multi-layer waterproof anti-rust paper inside, fixed on solid anti-slip wooden pallets, fully covered with rain tarpaulin for sea transportation moisture & scratch prevention.
Stock ready within 5-7 days, container loading at Tianjin Port. FOB, CIF, CFR trade terms acceptable.
Attached complete documents: EN10204 3.1 material certificate, mechanical test report, galvanizing salt spray test report, dimensional inspection sheet, packing list, commercial invoice.
11. Customization & Supporting Services
CNC cutting, beveling, bending, punching and tapping deep processing for non-standard thickness, width & length
Anti-corrosion customization: Shot blasting rust removal, anti-rust primer, electro-galvanizing, heavy hot-dip galvanizing, Zn-Al-Mg coating
Custom production of high-precision cold drawn bright flat bar, spring flat bar
One-stop supply of complete galvanized grounding flat bar with matching grounding terminals & galvanized fittings
Small batch sample orders & full container bulk export orders are both acceptable
Send Inquiry to This Supplier
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