Steel flat bar: sizes, grades and finishes
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A flat bar is a long steel strip with a rectangular cross-section, ordered by width × thickness. European stockist MetalXact lists hot-rolled flat bar in grade S235JR to EN 10025 and EN 10058, in sizes from 10 × 3 mm to 250 × 20 mm.
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What a flat bar is
A flat bar is a strip of metal with a rectangular cross-section: wider than it is thick, flat on all four faces. US stockist Metal Supermarkets describes it as a rolled or extruded product made in mild steel, stainless steel, aluminium, brass, copper and other metals, easy to cut, bend and drill.
In Tanzania the same product is made locally. Lodhia Industries describes them as rectangular steel sections of consistent thickness that can be cut, drilled, machined or welded, offered in a range of widths and thicknesses.
Hot-rolled or bright finish
Steel flat bar comes in two finishes, and they are made differently:
| Hot-rolled | Bright (cold-finished) | |
|---|---|---|
| How it is made | rolled at high temperature, above about 926°C, according to Rapid Metals | finished cold after rolling, for a smoother surface and tighter size |
| Grade and standard (MetalXact) | S235JR (1.0038), EN 10025 and EN 10058 | S235JRC+C (1.0122), EN 10277 |
| What you get | standard tolerances, mill surface | precise dimensions, smooth surface |
Sources: Rapid Metals (UK); MetalXact.
MetalXact describes the cold-drawn version as the one with precise dimensions and a smoother surface, so it is the choice where size or finish has to be exact. Either can be painted, coated or galvanised afterwards, Rapid Metals notes, and MetalXact supplies hot-dip galvanised bar to EN ISO 1461.
Steel flat bar sizes
Sizes are given width first, then thickness: 50 × 6 mm is 50 mm wide and 6 mm thick. MetalXact’s hot-rolled range runs from 10 × 3 mm up to 250 × 20 mm, including widths of 20, 25, 30, 40, 50, 60, 80 and 100 mm.
Many sellers still use inches. UK stockist Rapid Metals lists imperial widths in millimetres, which gives this conversion:
| Width in inches | In millimetres |
|---|---|
| ¾ in | 19.1 mm |
| 1 in | 25.4 mm |
| 1½ in | 38.1 mm |
| 2 in | 50.8 mm |
| 3 in | 76.2 mm |
So a “2 inch” bar is 50.8 mm wide, not 50 mm: close, but not the same size if it has to fit a slot or a bracket.
Uses in building and fabrication
Tanzanian mills list it too: Kamal Steel names mild steel flat bars among its products. Lodhia Industries lists building frames and support structures, fabrication, architectural and decorative work, gates, grills, fences and windows, agricultural tools and trailer parts. Metal Supermarkets adds framing and bracing, machine parts, automotive brackets and railings. For the hollow sections used alongside it in frames and gates, see square pipe and hollow sections.
What to check when you buy flat bar
- Width and thickness in millimetres, and whether the seller’s size is metric or converted from inches.
- Grade and standard — for example S235JR to EN 10025.
- Finish — hot-rolled, bright or galvanised.
- Length of each bar, and whether it can be cut to size.
- Straightness and edges, especially for visible work such as grills and railings.
Flat bar in Zanzibar
Kitovu sells from stock in Zanzibar, and flat bar is not among its products. For other steel sections, see steel pipes and chequered plate.