What DX51D Means
DX51D is the designation for a continuous hot-dip coated steel flat product intended for cold forming, defined in EN 10346. Reading the designation from left to right: the first letter D means a flat product for cold forming, the second letter X means there is no restriction on the substrate, so the strip may be produced from either hot-rolled or cold-rolled base material, the number 51 identifies the steel grade within the DX series, and the final letter D indicates a hot-dip coating. When zinc is used, the product is written DX51D+Z, and when an aluminium-zinc coating is used, DX51D+AZ. The same logic applies to the whole DX family: DX52D, DX53D and DX54D step up in drawability, while S220GD to S550GD cover structural grades with guaranteed higher yield strengths.
Ductility and Forming Behaviour
DX51D is highly ductile and flexible, which is why it is the default grade for bent, punched and lightly drawn parts. It is used in complex deep-drawn components, roll-formed profiles, cable trays, ducting, furniture components and general sheet metal work, and it is supplied in a wide thickness range from 0.12 mm up to 4.0 mm with widths to suit the customer's decoiling line. Because the base material is low carbon steel, DX51D accepts conventional bending, stamping and roll forming without special tooling, provided the bend radius respects the coating class: heavier coatings such as Z275 require a larger minimum bend radius so the zinc layer does not micro-crack on the outside of the bend.
DX51D vs SGCC
SGCC is the Japanese designation from JIS G3302 for hot-dip zinc-coated steel sheet and strip of commercial quality, and it is the closest equivalent to DX51D in the Japanese system. In practice, DX51D+Z and SGCC are treated as interchangeable for most commercial applications, and many suppliers quote them together. The differences are administrative rather than fundamental: the two products follow different standards, so the mill certificate, tolerances and test requirements differ, and the buyer should state the governing standard on the order. On the coating side, both use the same zinc coating concept: SGCC uses F-class designations such as F06 and F18, while DX51D+Z uses Z-class designations such as Z80 and Z275, with the number representing the nominal coating mass in grams per square metre over both surfaces.
DX51D vs DC51D
The difference between DX51D and DC51D is the substrate guarantee. DX51D can be produced from both cold-rolled and hot-rolled steel, so the mill chooses the substrate that meets the required properties; DC51D is typically produced from cold-rolled steel only, and the second letter C makes that cold-rolled substrate explicit. For the buyer, the practical effect is small in most applications, but DC51D is the safer specification where surface quality and consistency are critical, because the cold-rolled substrate gives a smoother, more uniform surface before coating.
Coating Classes: What Z200 and Z275 Mean
| Coating class | Coating mass (g/m2, both sides) | Typical use |
|---|---|---|
| Z80 | 80 | Indoor panels, light structures |
| Z100 | 100 | General construction, fencing |
| Z120 | 120 | Roofing sheets, wall panels |
| Z200 | 200 | Humid environments, long-service outdoor parts |
| Z275 | 275 | Coastal areas, solar mounting, aggressive atmospheres |
Z200 and Z275 are heavy coating classes chosen where the service life requirement dominates over forming severity. The coating mass is measured over both surfaces by the triple-spot method, and heavier coatings improve corrosion resistance but reduce the minimum bend radius that the material can tolerate. Where the part will be stamped deeply, the coating class and the forming parameters must be matched together.
Ordering Checklist for DX51D or SGCC Coil
1. State the standard (EN 10346 for DX51D+Z or JIS G3302 for SGCC), the thickness, width and coil weight. 2. Specify the coating class, for example Z200 or Z275, and the spangle type if appearance matters. 3. Confirm the surface treatment: passivation, chromate-free passivation, oiling or a combination. 4. Request the mill certificate with the coating mass result and the mechanical test values so the delivery can be verified.
Frequently Asked Questions
What is DX51D+Z200 material? DX51D+Z200 is a hot-dip galvanized steel coil per EN 10346: grade DX51D for cold forming with a zinc coating class of Z200, meaning 200 g/m2 of zinc measured over both surfaces.
Is DX51D the same as SGCC? They are the closest equivalents in the European and Japanese systems and are interchangeable for most commercial applications, but they follow different standards, so the certificate and tolerances come from the standard stated on the order.
What is the difference between DX51D and DC51D? DX51D may be produced from hot-rolled or cold-rolled substrate, while DC51D is typically produced from cold-rolled substrate only, giving a smoother and more consistent surface before coating.
What does Z275 mean? Z275 is a coating class of 275 g/m2 of zinc measured over both surfaces, the heaviest common class, used for coastal and highly corrosive environments such as solar mounting structures.
Can DX51D be deep drawn? DX51D handles bending and moderate drawing well; for severe multi-stage deep drawing, the higher grades DX52D, DX53D and DX54D are the appropriate choices.
Which standard governs DX51D? EN 10346 covers continuous hot-dip coated steel flat products and defines the DX51D grade, its properties and the Z and AZ coating classes.