Product Name

Small-Section Steel Flat Bar

1. Overview

Small-Section Steel Flat Bar refers to rectangular flat bars with relatively small cross-sections (moderate width-to-thickness ratio). They are commonly used for light structural members, assembly strips, support bars, hangers, trim strips, machine accessories, fastening plates and replacement parts. Compared with medium or large flat bars, small-section flats are easier to cut, punch, bend and install on site, and are suitable for light loads or uses such as panels, frames, supports and decorative trims.

2. Typical Material Grades

Carbon structural steels (common): Q195 / Q235 / S235 / A36 - general-purpose, economical, good weldability.

Medium carbon / heat-treatable: 1045 / C45 - when higher strength or quench/tempering is needed.

Stainless steels (corrosion/appearance): 304 / 316 / 430 - for corrosion resistance or aesthetic requirements.

Pre-galvanized / cold-rolled: used where surface quality is important or for easy downstream coating.

When choosing material, state the working environment (indoor/outdoor/coastal/chemical), load type and whether welding or heat treatment will be required.

3. Common Sizes (small-section typical stock)

Width (b): 10 mm – 80 mm (typical: 12 / 15 / 20 / 25 / 30 / 40 / 50 / 60 mm).

Thickness (t): 1.5 mm – 10 mm (typical: 1.5 / 2 / 2.5 / 3 / 4 / 5 / 6 / 8 / 10 mm).

Lengths: standard 1 m / 2 m / 2.44 m (8 ft) / 3 m / 6 m; cut-to-length available.

Supply conditions: hot-rolled, cold-rolled (cold-drawn/bright), pickled & oiled, pre-galvanized, planed/ground (for high flatness).

4. Weight & Section Properties (calculations)

Section area AAA (mm²) = b×tb \times tb×t

Mass per metre (kg/m) = A×0.00785=b(mm)×t(mm)×0.00785A \times 0.00785 = b(\text{mm}) \times t(\text{mm}) \times 0.00785A×0.00785=b(mm)×t(mm)×0.00785

Second moment of area III (bending about axis perpendicular to thickness):

I=b t312(mm4)I = \dfrac{b\,t^{3}}{12}\quad (\text{mm}^4)I=12bt3​(mm4)

Section modulus SSS (if extreme fiber distance = t/2t/2t/2):

S=It/2=b t26(mm3)S = \dfrac{I}{t/2} = \dfrac{b\,t^{2}}{6}\quad (\text{mm}^3)S=t/2I​=6bt2​(mm3)

Worked examples (step-by-step):

25 × 3 mm: area = 75 mm² → mass = 75 × 0.00785 = 0.58875 kg/m ≈ 0.589 kg/m.

20 × 2 mm: area = 40 mm² → mass = 40 × 0.00785 = 0.314 kg/m.

50 × 4 mm: area = 200 mm² → mass = 200 × 0.00785 = 1.57 kg/m.

30 × 6 mm: area = 180 mm² → mass = 180 × 0.00785 = 1.413 kg/m.

Use these formulas for quick material and transport weight estimates; final billing/transport should use actual weighed mass.

5. Tolerances & Machining Accuracy

Hot-rolled (standard): wider width/thickness tolerances - specify if tight tolerance needed.

Cold-rolled / cold-drawn (bright): tighter dimensions and smoother surface - suitable where finish or close fit is required.

Planed / ground: achieves higher flatness and thickness accuracy for bearing plates or contact surfaces.

Straightness / edge finish: generally good for small sections; specify if stricter straightness or burr-free edges are required.

6. Surface Treatments & Corrosion Protection

Mill finish (black): lowest cost; suitable for welding and subsequent coating.

Pickled & oiled: short-term rust protection, suitable for storage/export.

Electro-galvanized / hot-dip galvanized (HDG): small-section parts can use electro-galvanize; outdoor use recommends HDG or duplex (galvanize + coating).

Phosphate + primer/topcoat / powder coating: for appearance and corrosion protection.

Stainless as-supplied: no coating required for corrosion resistance or decorative use.

7. Typical Factory Value-Added Services

Cutting: sawing, plasma or laser cut to length/shape.

Punching / drilling / slotting: pre-drill bolt patterns to save site time.

Bending / light forming / hems: limited forming depending on thickness.

Welded assemblies / pre-assembly: small welded brackets, stiffeners, splice kits.

Planing / surface grinding: for flat bearing faces.

Coatings: galvanizing, painting, powder coating.

Kitting: pack with bolts/washers and installation drawings.

8. Quality Control & Inspection

Mill Test Certificate (MTC): chemical composition and mechanical properties on request.

Dimensional checks: width, thickness, length and hole position reports.

Mechanical tests: tensile tests and, if required, impact tests per contract.

Coating inspection: coating thickness, adhesion and appearance checks.

Factory inspection report and batch identification for traceability and site acceptance.

9. Typical Applications

Light support strips, hangers, decorative trims.

Machine accessories, control panel strips, guide rails.

Frame members, shelf crossbars, door/window fittings, fence rails.

Small splice plates, hinge plates, seat plates, bearing shims and repair patches.

Electrical cabinet accessories, signage rails and architectural trims.

10. Design & Selection Advice (practical)

Define working conditions: state if member is load-bearing (bending/axial/shear), subject to impact/fatigue, expected temperature and corrosive exposure.

Choose material accordingly: outdoor/corrosive → galvanized or stainless; fatigue/structural → consider heat-treatable alloys (1045/4140).

Thickness vs width: thickness strongly affects bending stiffness (I∝t3I \propto t^3I∝t3); increase width when more contact area is needed.

Local reinforcement: add bearing plates or stiffeners near holes and concentrated loads to avoid local buckling or fatigue.

Allow machining allowance if planing or grinding will follow.

Plan transport/installation: if single-piece length exceeds transport or handling limits, plan splicing with alignment holes.

11. Packaging, Identification & Logistics

Packaging: bundle by size onto wooden pallets or steel racks, use spacers and steel strapping; protect surfaces with plastic wrap or rust preventive.

Identification: each bundle labeled with size, length, quantity, heat/lot number and PO.

Shipping: short pieces suitable for regular carriers; long or bulk loads can be arranged by truck with loading/unloading guidance.

Storage: avoid long-term outdoor exposure; store indoors or under waterproof cover.

12. Lead Times (guidance)

Stock common small-section sizes: 3–10 working days (subject to inventory and quantity).

Orders requiring punching/coating/kitting: 1–3 weeks depending on operations and volume.

Special materials (stainless/alloy) or third-party inspection: 2–6 weeks or per contract.

13. Ordering Information - What to Provide

Size list: width × thickness × length × quantity (or a detailed cut list).

Material grade and whether MTC is required.

Surface treatment: mill / pickled & oiled / electro-galvanized / HDG / painted / planed.

Processing requirements: hole drawings, slots, bends, weld assemblies, etc.

Tolerance and flatness requirements, if critical.

Inspection requirements (third-party witness, NDT), delivery schedule and transport constraints.

14. FAQ (Common Questions)

Q: How to quickly calculate the weight per metre?
A: mass (kg/m) = b(mm) × t(mm) × 0.00785.

Q: Which dimension matters more for bending stiffness?
A: Thickness; bending stiffness scales with t3t^3t3. Width affects contact area and distribution.

Q: What surface treatment for outdoor light-duty use?
A: Electro-galvanizing is common for small parts; for long-term durability choose HDG or duplex systems.

Q: Can you deliver kitted assemblies (with bolts/washers)?
A: Yes - we can pre-pack items into kits and include installation notes.

If you'd like, I can immediately do one of the following (no waiting):

Generate a per-item weight and bundle plan from your size × quantity list; or

For a specific load/span case, recommend 2–3 candidate sizes and run quick strength/deflection checks; or

Prepare a supplier RFQ template (technical spec, inspection and delivery clauses) for you to send to vendors.

Send either the size list or the working parameters and I'll prepare the requested output right away.

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