Product Name
Flat Steel for Vehicles (Automotive & Transport Flat Bars)
Introduction
Flat steel for vehicles are rectangular steel bars and strips specified for automotive and transport manufacturing - chassis components, mounting plates, reinforcement straps, bumper supports, door sills, brackets, floor pans, cross members and general-purpose structural parts. They're produced to meet tight dimensional and mechanical requirements, are easy to form/weld/machine, and can be delivered with corrosion protection and value-added shop work to go straight onto the production line.
Typical Materials & Grades
Mild / structural steels: S235 / A36 / Q235 (general use).
High-strength low-alloy (HSLA): S355, A572 Gr.50 for reduced thicknesses and weight savings.
Automotive high-strength steels: Dual-phase, bake-hardening and microalloyed steels (e.g., DP, BH) for forming applications.
Alloy & heat-treatable: 1045 / 4140 where higher strength or heat treatment is required.
Stainless: 304 / 430 / 409 for corrosion-prone or decorative parts.
Spring & wear grades: spring steel or AR inserts for wear contact areas.
Typical Forms & Supply Conditions
Hot-rolled flats: economical for thicker sections.
Cold-rolled / cold-drawn flats: tight tolerances and superior surface finish for visible or precision parts.
Precision ground / planed: bearing faces and shim plates.
Coils / cut-to-length strips: for stamping/press lines.
Surface conditions: mill, pickled & oiled, galvanized (electro or hot-dip), pre-painted, powder-coated.
Typical Sizes & Tolerances
Widths: 15 mm → 1,200 mm (common automotive: 20–200 mm).
Thicknesses: 1.5 mm → 30 mm (typical: 1.5–6 mm for body/trim; 6–20 mm for structural mounts).
Lengths: cut-to-length (1–12 m), coils for stamping lines; single-piece length limited by transport.
Dimensional tolerances: cold-rolled ±0.02–0.2 mm; hot-rolled wider tolerances; specify tolerance class for critical parts.
Mass formula: mass (kg/m) = Width(mm) × Thickness(mm) × 0.00785
Quick examples:
25 × 3 mm → 25 × 3 × 0.00785 = 0.589 kg/m
100 × 6 mm → 4.71 kg/m
200 × 10 mm → 15.7 kg/m
Key Features & Advantages
Formability: selected grades (DP/BH) readily form for pressed body parts without cracking.
High strength options: HSLA and heat-treatable steels allow lower gauge/weight for same performance.
Good weldability & machinability: supports MIG/MAG, resistance spot-weld and robotic welding processes.
Corrosion protection: pre-galvanized or coated options reduce downstream finishing steps.
Ready-to-assemble: pre-cut, punched, notched and finished to reduce line changeover and cycle time.
Traceability & certification: MTC and batch marking for safety-critical and regulatory parts.
Typical Applications
Chassis cross members, mounting plates and brackets.
Door sills, underbody straps and reinforcement flats.
Bumper supports, tow-eyes, hitch plates and drawbars.
Floor pan tie strips, seat mounting plates and anchor plates.
Brackets for fuel, brake, cable and harness supports.
Repair/patch flats and reinforcement strips in vehicle remanufacture.
Fabrication & Value-Added Services
CNC laser/plasma cutting & nesting for optimized material usage.
Punching & stamping for bolt patterns, slots and tab features.
Bending / press-brake / roll forming to final shape.
Welding & sub-assembly: tack-welded subframes, pre-welded gussets and jigged assemblies.
Heat treatment & tempering for alloy or high-strength requirements.
Surface finishing: hot-dip galvanize, electro-galvanize, phosphate, primer + topcoat, powder coat.
Kitting & sequencing for line-side delivery (JIT / just-in-sequence).
Quality Assurance & Testing
Material certificates (MTC): chemical and mechanical reports.
Mechanical tests: tensile, yield, elongation and hardness testing as required.
Dimensional & surface inspection: width, thickness, flatness, straightness and surface roughness checks.
Weld & assembly inspection: MT/PT/visual for critical joints; spot-weld testing for sheet operations.
Coating tests: film thickness, adhesion and salt-spray (if specified).
Traceability: heat/coil/lot marking for production control.
Packaging & Delivery
Coil or flat-stacked: timber/polymer spacers, strapped and edge-protected.
Kitted sets: packaged sub-assemblies and bolt kits per vehicle model/line sequence.
Protection: VCI film or light oil for export storage; crating for precision ground parts.
Lead times: stock sizes short; custom grades, coated or pre-processed kits depend on scope-lead-time provided with quote.
How to Order / What We Need
Please provide:
Width × Thickness × Length (or coil specification) and quantity.
Material grade and supply condition (hot-rolled / cold-rolled / coated / ground).
Tolerance / flatness requirements and any critical dimensions.
Value-added requests: cutting/Punching/bending/welding/heat-treatment/coating.
Testing/certification needs (MTC, tensile, spot-weld testing, coating tests).
Delivery logistics: JIT/JIS sequencing, packaging/labeling instructions and delivery schedule.
If you like, send a short size list or a single part drawing and I'll return a size-to-weight table, recommended grades for forming vs structural uses, and suggested cutting/finishing options ready for quoting.
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