Flat bar materials

• Stainless steel flats – 304/304L, 316/316L, 321, 310S, 410 and duplex on request, for corrosive, hygienic, high-temperature and architectural use.
• MS flats – mild steel to IS 2062 and ASTM A36 for general fabrication.

How flat bars are made

Hot-rolled flats are rolled directly to width and thickness, with slightly rounded edges; stainless flats are then annealed and pickled. Cold-drawn or cold-finished flats have sharper edges, a smooth surface and closer tolerances, and are used for machined parts and visible work. Sheared or cut flats are cut from plate by shearing, plasma or laser, for wider and thicker sizes and special dimensions; their edges may be left as cut or machined. Flats are described by width and thickness – for example 50 × 6 mm.

Standards and sizes

Mild steel grades

Yield strength reduces for thicker sections as given in each standard. The sub-grade letter in IS 2062 and EN 10025 indicates impact testing (for example BR or J2), which matters for structures in cold climates or under dynamic loads.

Choosing the grade

304 and 304L flats are used for general fabrication, food machinery, architectural trims and railings. 316 and 316L are chosen for marine, chemical and pharmaceutical use. 321 and 310S are used for furnace parts, heat shields and high-temperature supports. Mild steel flats are used for general structures, base plates and brackets, and are painted or galvanised. For pressure parts machined from flat bar – such as small flanges or plates – ASTM A479 bar is specified, as it carries the requirements for pressure-vessel use.

Fabrication

Flats are sawn or sheared to length, drilled, punched, bent and welded. Stainless flats are welded with matching filler and pickled and passivated after welding. Cold-drawn stainless flats can become slightly magnetic because of cold work; annealing restores the non-magnetic condition if needed.

Applications

Flat bars are used for base plates, cleats, gussets and stiffeners, brackets and hangers, frames and supports, bus bars and earthing strips, railings and balusters, grating bearing bars, conveyor and machine parts, and decorative trims. Related products are on our angles, channels and round bars, rods and wires pages, and all products on the products page.

Weight, handling and storage

Flat bars are sold by weight or by length. Theoretical weight per metre is calculated from the cross-section and the density – 7.85 g/cm³ for mild steel and about 7.9–8.0 g/cm³ for stainless steel – and can be checked with our weight calculator. Actual weights vary with rolling tolerances, so invoiced weights are based on the weighed or calculated figures agreed with the order. Bundles are sized for safe handling by crane or forklift.

Store structural sections off the ground on timber bearers, under cover where possible, and keep stainless steel apart from mild steel to avoid contamination and rust staining. Galvanised sections should be stacked with spacers so that rainwater can drain, preventing white rust.

Flats for earthing and electrical use

Galvanised mild steel flats and copper-bonded or stainless steel flats are used for earthing strips and lightning protection conductors, with sizes chosen for the fault current and corrosion allowance. Stainless steel flats are increasingly used for earthing in corrosive soils and coastal sites because they keep their cross-section far longer than galvanised steel.

Quality checks

Before dispatch, flat bars are checked against the order for grade, size, length and quantity, and the heat numbers on the material are matched to the mill test certificates. Straightness and surface condition are inspected visually, and dimensions are checked against the tolerances of the product standard. For project orders, material can be marked with item or tag numbers, colour coded by grade, and packed by delivery area to make site receiving easier. Third-party inspection by the buyer's nominated agency can be arranged at our premises.

Documents and ordering

All structural sections are supplied with mill test certificates (MTC) showing heat number, chemistry and mechanical properties, and third-party inspection is available on request. Sections are bundled and tagged with grade, size and heat number; stainless sections are packed with protection to keep them separate from carbon steel and free of surface contamination.

Please give the material and grade, width and thickness, hot rolled, cold drawn or cut from plate, length, finish, quantity and any inspection requirement.