In short
DX51D is the general-purpose galvanized steel grade in EN 10346 for bending and roll-forming. DX52D, DX53D and DX54D offer increasing deep-drawing ability, while codes such as S250GD–S350GD give the minimum yield strength for structural uses. Corrosion resistance is set by the zinc mass given by the Z number, not by the grade.
How to read the label
A designation such as DX51D+Z275-N-A-C on a galvanized coil or sheet label is the product's full description under the European standard EN 10346:
| Part | Meaning |
|---|---|
| DX51D | Steel grade (formability) |
| +Z | Coating type: zinc. +ZA is zinc-aluminium, +AZ aluminium-zinc, +ZM zinc-magnesium. |
| 275 | Total zinc mass on both sides, g/m² |
| N / M | Spangle: N normal, M minimised |
| A / B / C | Surface quality: A standard, B and C more flawless surfaces for painted or visible parts |
| C, O, CO… | Surface treatment: C chemical passivation, O oiled, CO both |
DX grades: forming classes
Grades starting with DX are low-carbon steels for cold forming. The higher the number, the softer and more ductile the steel and the deeper it can be drawn without tearing. Approximate mechanical values in EN 10346:
| Grade | Use | Yield strength (MPa) | Tensile strength (MPa) | Elongation A80 (min.) |
|---|---|---|---|---|
| DX51D | Bending, roll-forming, general fabrication | Not specified | 270–500 | 22% |
| DX52D | Drawing quality | 140–300 | 270–420 | 26% |
| DX53D | Deep drawing | 140–260 | 270–380 | 30% |
| DX54D | Special deep drawing | 120–220 | 260–350 | 36% |
Exact values vary slightly with thickness and mill; the binding document is the mill certificate delivered with the material.
When is DX51D enough?
For most bending and roll-forming work, such as ventilation ducts, cabinets, doors, trapezoidal sheet and sections, DX51D is sufficient and it is the most common and available grade. For deep-drawn parts such as containers, tanks, automotive and appliance parts, where the steel stretches considerably, DX52D or higher is chosen. Deep drawing DX51D can cause tearing and cracks.
S250GD, S350GD: structural grades
Grades starting with S and ending in GD are for load-bearing uses; the number is the minimum yield strength in MPa, so S350GD guarantees at least 350 MPa. For light steel sections, racking and floor deck sheet sized by structural calculation, use the S grade specified in the design.
A common mix-up: grade does not set corrosion resistance
The difference between DX51D and DX52D is formability, not rust resistance. Corrosion resistance comes from the coating mass: a Z275 DX51D sheet lasts longer outdoors than a Z100 DX53D sheet. See Z100–Z275 coating classes.
Equivalents in other standards
DX51D also existed under the same name in the former European standard EN 10142, replaced by EN 10346. Approximate equivalents are SGCC in the Japanese standard JIS G3302 and ASTM A653 CS Type A in the US standard. These matches are approximate for general use; mechanical values are not identical.
What to specify when ordering
Along with thickness and size, state the grade (e.g. DX51D), coating class (e.g. Z275) and, if the steel will be painted, the surface treatment. If unsure, tell us what the part is for and we will help choose the grade. See galvanized sheet and galvanized coil.
This article was prepared by the İpek Metal technical team. Contact us for values specific to your project.