DX51D and DX52D Coil: What the Grade Codes Mean
DX51D and DX52D are European designations for continuously hot dip zinc coated steel sheet supplied in coil. The letters identify a product intended for cold forming, and the final D indicates a coating applied by the hot dip process. DX51D is a commercial quality forming grade used wherever bending and light profiling are the main demands. DX52D is a drawing quality grade, with a wider forming window that suits components requiring deeper deformation.
Both grades begin as full hard cold rolled sheet. The strip is pickled and rolled to final gauge, then passed through the zinc pot so that a zinc layer is deposited on both surfaces. That metallurgically bonded coating is what gives the material its corrosion resistance, paintability and processing behaviour.
Grade Comparison
| Item | DX51D | DX52D |
|---|---|---|
| Forming class | Commercial quality | Drawing quality |
| Yield strength range | 140 to 320 MPa | 140 to 300 MPa |
| Tensile strength range | 270 to 500 MPa | 270 to 420 MPa |
| Minimum elongation, A80 | 22 % | 26 % |
| Typical use | Panels, ducting, profiles, general fabrication | Drawn and formed building components |
Property ranges follow the EN 10346 requirements for these grades. Because DX52D offers higher ductility, it is selected when a part has to stretch rather than simply bend.
Coating Designation and Mass
Coating is designated by the letter of the coating family followed by the total coating mass in grams per square metre for both surfaces. A Z275 coating therefore carries 275 g/m2 of zinc in total, not per side. Heavier coatings extend service life but reduce the forming window slightly, because a thick intermetallic layer is less ductile than the steel beneath it.
Z coatings: pure zinc, the standard choice for general building work
ZF coatings: zinc iron alloy, favoured where paint adhesion and weldability are priorities
AZ coatings: zinc aluminium, chosen for long life in aggressive outdoor exposure
Coating mass range: Z30 up to Z275 in this product family
Coil can be supplied with a regular spangle, minimised spangle, large spangle or zero spangle surface, depending on whether the sheet receives a skin pass after coating. Zero spangle and minimised spangle surfaces are normally chosen for painted applications where a smooth, uniform appearance is required.
Product Specifications
| Parameter | Range or option |
|---|---|
| Applicable standards | GB, JIS and ASTM specifications, plus EN 10346 |
| Thickness | 0.1 mm to 4.0 mm |
| Width | 500 mm to 1250 mm |
| Zinc coating | 30 g/m2 to 275 g/m2 |
| Surface treatment | Chromated, unoiled or dry |
| Spangle | Regular, minimised, large or zero spangle |
Corrosion Behaviour in Service
In typical atmospheric environments the zinc coating provides maintenance free corrosion protection for 20 to 70 years or longer, and the life cycle cost is correspondingly low. The coating covers inner and outer surfaces, edges and corners, so protection is continuous around the component with no dead angles. The alloy layer formed between zinc and steel is metallurgically bonded and hard, and resists damage during transport, processing and installation. Even if the coating is breached locally, zinc continues to protect the exposed steel by sacrificial action, which is the reason thin coated sheet outperforms bare or painted carbon steel in the same exposure.
Applications and Processing Guidance
Hot dip galvanized coil in these grades is used for fencing, greenhouse structures, door and tube products, low pressure liquid, water, gas and oil line pipe, indoor and outdoor building construction, and scaffolding systems where a light, economical and durable material is needed. Coil can be slit, profiled, roll formed, bent and joined by conventional methods, and it can be supplied in customised packaging with a chosen number of strips per bundle, pallet type and label placement so that coils arrive undamaged. For drawing operations, DX52D is the safer starting point; for bending and profiling, DX51D gives adequate formability with a wider strength range.
FAQ
Q: What does DX51D mean?
DX51D is a commercial quality continuously hot dip zinc coated steel grade intended for cold forming, where bending and light profiling are the main operations.
Q: What is DX52D used for?
DX52D is a drawing quality grade with higher elongation, so it is used for building components that need deeper forming than simple bending.
Q: Does Z275 mean 275 g/m2 on each side?
No. The number designates the total coating mass for both surfaces, so Z275 carries 275 g/m2 of zinc in total.
Q: How is hot dip galvanized coil produced?
Full hard cold rolled sheet is pickled and rolled, then passed through a molten zinc pot so that zinc is deposited on both surfaces of the strip.
Q: Which coating should be chosen for outdoor building work?
Standard zinc coatings suit general construction, while zinc aluminium coatings are selected where aggressive outdoor exposure requires a longer service life.
Q: What surface finishes are available?
Coil can be supplied chromated, unoiled or dry, with regular, minimised, large or zero spangle surfaces depending on the application and appearance required.
Q: What makes galvanized coil corrosion resistant?
The bonded zinc layer protects edges and corners continuously and keeps working by sacrificial action even where the coating is locally damaged.