# Flat bar stock

Rectangular metal stock: manufacturing routes, dimensional conventions, edge condition and procurement boundaries.

Reviewed: 2026-11-01

Tags: materials, stock-forms, flat-bar

## What flat bar identifies

**EN 10058:2018** covers hot-rolled steel flats and wide flats for general purposes, excluding spring leaves. Its designation uses **width × thickness × length in mm**. The preview allows an undefined rounded corner from manufacturing. Put a sharp locating edge or controlled radius on the order explicitly. [SIST EN 10058 preview](https://preview.sist.si/sist-preview/64327/193669ce71dd44dcb6a215115e681d31/SIST-EN-10058-2019.pdf)

Flat bar is elongated stock with a rectangular cross-section. It describes geometry and commercial supply form, not a unique alloy, strength level, heat treatment or tolerance. A bracket blank, wear strip and precision tooling blank may all start as flat stock while requiring very different material and surface conditions.

## Routes that can produce a rectangular strip

| Route | Selection question |
|---|---|
| Hot-rolled flat bar | Which dimensional standard, edge geometry and surface condition are supplied? |
| Cold-finished or cold-drawn flat | Which finishing process, tolerance and mechanical condition are certified? |
| Strip cut from plate | What parent plate, cutting method, edge condition and orientation are retained? |
| Precision-ground flat stock | Which grade, heat-treatment condition and grinding tolerances apply? |

Nucor describes hot-rolled flats as a bar product and contrasts hot-rolled supply with cold-finished steel's smoother finish and tighter dimensional control. Its cold-finished page describes additional processing after hot rolling and permits sharp corners or specified radii on cold-drawn flats. These are process/product descriptions, not numerical tolerances for every grade and size. Neither webpage supplies a verified technical issue date. [Nucor hot-rolled bar](https://nucor.com/products/hot-rolled-bar/), [Nucor cold-finished bar](https://nucor.com/products/cold-finished-bar/)

Do not infer interchangeability from equal width and thickness. Valbruna Nordic explicitly offers stainless flat bars in **two executions: hot rolled and cut from plate**, with grades 1.4307 and 1.4404 listed. Its stock programme determines the grade/size/execution combinations. That named example shows why the supply route belongs on the order; it does not make those stainless grades interchangeable in service. No issue date was verified on the page. [Valbruna Nordic flat bar](https://www.valbrunanordic.se/en/stainless-steel-bars/our-standard-profiles/flat-bar/)

## Standards, dimensions and edges

**EN 10058:2018** covers nominal dimensions and dimensional/shape tolerances of hot-rolled steel flat bars and wide flats for general purposes; spring leaves are excluded. Its designation separates **width × thickness × length in millimeters**, length type and steel identity. The public SIST adoption is labeled **SIST EN 10058:2019**; DIN's national publication is **February 2019**. Keep the European edition distinct from its national publication year. [SIST official preview, clauses 1 and 4](https://preview.sist.si/sist-preview/64327/193669ce71dd44dcb6a215115e681d31/SIST-EN-10058-2019.pdf), [DIN EN 10058:2019-02](https://www.dinmedia.de/en/standard/din-en-10058/293454414)

The standard's preview notes that manufacturing may leave corners with an undefined rounded shape. Therefore an application requiring a sharp locating edge or a controlled corner radius needs an explicit requirement rather than an assumption about “square bar edges.” Use the stated edition and scope. [SIST preview, foreword and clause 5](https://preview.sist.si/sist-preview/64327/193669ce71dd44dcb6a215115e681d31/SIST-EN-10058-2019.pdf)

For plate-cut material, agree which requirements apply to the parent plate and which apply to the finished strip. Record cut-edge squareness, burr/dross removal and subsequent machining requirements separately from the broad-face finish. A dimensional standard for hot-rolled flats should not be assumed to certify an unspecified cutting process.

## Ground stock is a named product condition

Precision Marshall's ground-flat-stock page states that its products are made from cross-rolled sheet or plate, ground on thickness and width and free of decarburization. It identifies annealed tool-steel examples and also lists prehardened 4140/4142 stock. Ground surfaces therefore do not imply one universal heat-treatment state. The supplier describes approximately **0.005 inch per foot as a flatness aim**, which should not be silently converted into a contractual guarantee. The webpage has no verified issue date. [Precision Marshall ground flat stock](https://pmsteel.com/products/precision-ground-flat-stock/)

For tooling, agree whether the delivered dimensions are finish size or allow further grinding, and whether subsequent hardening is required. Preserve the exact grade and condition rather than storing “ground flat” as if it were a material designation. A stated surface finish or decarburization condition concerns the supplied product; acceptance after later processing remains a separate question.

## Cutting and machining boundaries

SSAB's cutting guidance distinguishes thermal cutting—such as laser, plasma and oxy-fuel—from mechanical processes such as sawing and shearing. It explains that a thermal cut can alter the unmelted material next to the edge, and that the heat-affected zone depends on grade, thickness and heat input. Its process recommendations are expressly bounded to SSAB products. No technical revision date was verified on the page. [SSAB, 20 questions about cutting](https://www.ssab.com/en/support/how-to-process/how-to-cut/20-questions-about-cutting)

## Worked purchasing estimate

**Illustrative assumptions:** one nominal rectangular carbon-steel bar, 50 mm wide, 10 mm thick and 6.000 m long; no holes, coatings or removed material. Use **7850 kg/m³** solely as the estimation density. EN 10058 uses 7.85 kg/dm³; stainless mass uses grade-specific density. [SIST preview, Table 1 footnotes](https://preview.sist.si/sist-preview/64327/193669ce71dd44dcb6a215115e681d31/SIST-EN-10058-2019.pdf)

Area = 50 × 10 = **500 mm²**. Nominal volume = 0.050 × 0.010 × 6.000 = **0.00300 m³**. Estimated mass = 0.00300 × 7850 = **23.55 kg**, or **3.925 kg/m** before rounding.

This is a mass estimate, not a weighbridge result or a structural capacity. Dimensional tolerances, rounded corners, length variation and surface treatments can change actual mass. Recalculate with the actual material density when using another alloy.

## Ordering and receiving checklist

1. Identify grade, product/quality standard and edition, supplied condition and certificate requirements.
2. State width, thickness, length, units, dimension order and the required tolerance provisions.
3. Specify rolled, cold-finished, plate-cut or ground supply, including edges and surfaces that matter.
4. Agree cutting, finishing and inspection requirements before approving substitutions.
5. Retain heat/lot identity through cutting and compare incoming stock with the purchase requirements, separately from finished-part acceptance.

Keep the ordered nominal dimensions with their tolerance source and the lot with its process and condition.

## Related reference

[Stock forms and dimensions](index.md)