# EN DX51D coated steel

Cold-forming coated flat steel: DX51D base grade, metallic-coating designation, mass/test basis, surface condition and standard-edition control.

Reviewed: 2026-11-01

Tags: materials, steel, coated-steel, sheet

## Specify steel, coating and edition separately

SSAB's **EN 10346:2015-basis DX51D** row gives **270–500 MPa tensile strength** and **22% minimum A80** before gauge adjustments. At **0.60 mm**, the two-point deduction gives **20%**. At **0.50 mm**, the four-point deduction gives **18%**. The tests are transverse and the row specifies no yield value. Check the ordered edition for the applicable requirements, including when ordering to **EN 10346:2026**. [SSAB mechanical table and thickness footnote](https://www.ssab.com/en/brands-and-products/steel-categories/coated-steel/metal-coated-formable-steels)

DX51D is a low-carbon cold-forming steel designation within the continuously hot-dip-coated flat-product family. SSAB offers DX51D with **Z, ZA and ZF** coatings in its product page explicitly headed **EN 10346:2015**. The base-steel name alone does not specify a complete coating, finish or surface-protection system. [SSAB formable coated steels](https://www.ssab.com/en/brands-and-products/steel-categories/coated-steel/metal-coated-formable-steels)

**Edition matters:** BSI now lists **BS EN 10346:2026**, identical to EN 10346:2026, as current and published 31 October 2026. Its 2015 page is marked withdrawn. The 2026 public scope covers coated flat products at 0.20–6.5 mm and distinguishes coating families including Z, ZF, ZA, AZ, ZM, AS and A. This public scope does not establish every grade/coating combination or the complete acceptance tables. [BSI current edition](https://knowledge.bsigroup.com/products/continuously-hot-dip-coated-steel-flat-products-for-cold-forming-technical-delivery-conditions-1), [BSI 2015 record](https://knowledge.bsigroup.com/products/continuously-hot-dip-coated-steel-flat-products-for-cold-forming-technical-delivery-conditions)

## Mechanical data: formability without an invented yield rating

SSAB's stated 2015-basis DX51D row gives **Rm 270–500 MPa** and **minimum A80 elongation 22%**, with no specified yield, r90 or n90 value in that row. Its elongation footnote reduces A80 by two percentage points for 0.50 < t ≤0.70 mm and four for t ≤0.50 mm. Tests are transverse to rolling direction. [SSAB mechanical table and footnotes](https://www.ssab.com/en/brands-and-products/steel-categories/coated-steel/metal-coated-formable-steels)

For a load-bearing component, obtain an applicable yield requirement and separate structural design basis.

## Decode a complete named example

thyssenkrupp's covex T bulletin uses **DX51D+Z275-M A-C** as an ordering example:

| Element | Meaning in that producer example |
| --- | --- |
| DX51D | Steel grade |
| Z275 | Zinc-coated product, coating-mass designation 275 |
| M | Minimized spangle |
| A | Normal surface quality |
| C | Passivated surface protection |

These fields describe different attributes. A coating mass does not promise a particular cosmetic surface, and passivation is additional surface protection rather than the metallic coating itself. [thyssenkrupp covex T nomenclature](https://www.thyssenkrupp-steel.com/media/content_1/publikationen/produktinformationen/covex/thyssenkrupp_covex-t_product_information_steel_en.pdf)

Use that example only within its stated producer/edition basis. Confirm the actual permitted suffixes and sequence in the ordered standard and mill acknowledgement; do not construct an arbitrary combination from unrelated catalogues.

## Coating mass is total over both faces

thyssenkrupp's January 2023 zinc-coating table lists **Z275** as minimum **275 g/m² two-sided in the triple-spot sample**, with a separate **235 g/m² single-spot minimum**. It gives a typical thickness of **20 µm per face**, not a guaranteed uniform 20 µm everywhere. The table distinguishes mass requirements from local thickness guidance. [thyssenkrupp hot-dip-coated sheet Z, coating table](https://www.thyssenkrupp-steel.com/media/content_1/publikationen/produktinformationen/feinblech_z/thyssenkrupp_hot-dip-coated-sheet_z_product-information_steel_en.pdf)

**Original mass example:** a flat sheet 1.0 × 2.0 m has projected area 2.0 m². At a hypothetical exactly uniform total coating mass of 275 g/m², coating mass is 2.0 × 275 = **550 g over both faces**. Multiplying by two again would double-count the faces. This does not assert that every production sheet weighs exactly 550 g more: specified sampling, actual deposition and tolerances still apply.

Do not equate Z275 with ZA275, ZM275 or another chemistry merely by matching a number. Coating chemistry, mass, adhesion and subsequent processing must be selected together. A mass designation is not a guaranteed number of outdoor service years or a universal cut-edge-protection distance.

## Surface quality, processing and exposure

The zinc-coating bulletin distinguishes spangle appearance from coating quality. It also references **EN 10143** for dimensional and shape tolerances. Specify these separately from DX51D and the coating mass. [thyssenkrupp surface and tolerance guidance](https://www.thyssenkrupp-steel.com/media/content_1/publikationen/produktinformationen/feinblech_z/thyssenkrupp_hot-dip-coated-sheet_z_product-information_steel_en.pdf)

For visible panels, approve a finished sample with the intended forming and cleaning sequence. Define significant faces, scratches, waviness and inspection conditions. A normal-surface designation is not a mirror-finish requirement. For assembly, define coating repair or sealing at cuts, drilled holes, welds and damaged areas according to the actual service system.

The covex T bulletin warns that cleaning/degreasing can impair its passivation and recommends individual painting tests where special requirements apply. Its guidance belongs to that named additional coating, not every passivated coil. [thyssenkrupp covex T processing](https://www.thyssenkrupp-steel.com/media/content_1/publikationen/produktinformationen/covex/thyssenkrupp_covex-t_product_information_steel_en.pdf)

Resolve cleaning, paint pretreatment, adhesive compatibility and joining before choosing the delivery treatment. Qualify welding on the coated product with the appropriate fume controls and final corrosion-protection plan. Inspect bends and hems for the required substrate and coating integrity. Avoid treating a successful unformed coupon as evidence for all strained or welded surfaces.

## Procurement and source versions

Record mill/coil identity, certificate, contractual edition, thickness/tolerance, coating type/mass, sampling basis, significant face, finish/treatment and final acceptance tests. Preserve that identity after slitting or cutting; a service-centre label should remain connected to the mother-coil evidence.

SSAB's inspected page explicitly cites **EN 10346:2015** and shows no verified technical revision date. thyssenkrupp's zinc bulletin prints **January 2023, version 0**; covex T prints **December 2023, version 0**. BSI's current record is **2026**. This draft identifies those differing bases and does not claim that the full 2026 mechanical/coating requirements were independently verified from its public scope.

[Grades, tempers and conditions](../grades-tempers-and-conditions.md)