Steel sheet grade designations -
DX51D, DC01, S235JR, S350GD
A steel sheet grade designation encodes the intended forming route of the product, the rolling method and the guaranteed level of mechanical properties. In thin flat products, in the thickness range from 0.3 to 5 mm, four groups of designations apply, each taken from a separate standard: EN 10346 for continuously hot-dip coated products, EN 10130 for cold rolled products for cold forming, EN 10025-2 for general purpose structural steels and EN 10111 for hot rolled products intended for further cold forming.
Reading the designation correctly makes it possible to verify whether a purchase specification matches the actual requirements of the finished part, and to assess whether the selected grade has been over-specified. A mismatch usually becomes visible only during bending, drawing or service life of the finished component.
EN 10346
hot-dip coated products: DX51D to DX57D and S220GD to S350GD
EN 10130
cold rolled products for cold forming: DC01 to DC07
EN 10025-2
non-alloy structural steels: S235, S275, S355 with impact designation
EN 10111
hot rolled products for cold forming: DD11 to DD14
Structure of the grade designation
Steel sheet grade designations follow two separate logics. Products intended for cold forming carry a designation starting with the letter D, in which the following characters indicate the rolling technology and the forming class. Structural steels carry a designation starting with the letter S, in which the primary information is the minimum specified yield strength.
| Element of the designation | Meaning | Example |
|---|---|---|
| D in the first position | flat product intended for cold forming | DX51D, DC04, DD11 |
| X, C or D in the second position | rolling method: X not specified and left to the producer, C cold rolled, D hot rolled | DX52D, DC01, DD13 |
| two-digit number | increasing forming capability, linked to a cleaner chemical composition | DX51D to DX57D, DC01 to DC07 |
| D at the end of the designation | intended for continuous hot-dip coating | DX53D, S280GD |
| S with a number | structural steel with the minimum specified yield strength given in megapascals | S235, S350 |
| G after the number | flat product within the group of coated structural steels | S320GD |
| JR, J0, J2, K2 | required impact energy and test temperature | S235JR, S355J2 |
Designation rules according to EN 10027-1 and the product standards.
Continuously hot-dip coated products, EN 10346
The DX group covers materials intended for cold forming with a metallic coating applied in line. Higher numbers in the designation correspond to greater forming capability, accompanied by a lower and narrower yield strength range. For DX51D the standard does not specify yield strength, which means there is no guarantee of its repeatability between deliveries.
| Grade | Re [MPa] | Rm [MPa] | A80 min. | Typical use |
|---|---|---|---|---|
| DX51D | not specified | 270-500 | 22% | bending, roll forming, shallow drawing |
| DX52D | 140-300 | 270-420 | 26% | roll forming with a higher degree of deformation |
| DX53D | 140-260 | 270-380 | 30% | deep drawing |
| DX54D | 120-220 | 260-350 | 36% | high drawing requirements |
| DX56D | 120-180 | 260-350 | 39% | drawn parts of complex geometry |
| DX57D | 120-170 | 260-350 | 41% | drawn parts with the highest degree of deformation |
Values according to EN 10346 as compiled by a producer of coated products.
A separate group within the same standard covers structural grades with a metallic coating. The designation S250GD stands for a structural steel with a minimum yield strength of 250 MPa, supplied as a flat product intended for hot-dip coating. In this group selection is driven by the load capacity of the section rather than by formability, which is why the guaranteed elongation decreases as the yield strength rises.
| Grade | Re min. [MPa] | Rm min. [MPa] | A80 min. |
|---|---|---|---|
| S220GD | 220 | 300 | 20% |
| S250GD | 250 | 300 | 19% |
| S280GD | 280 | 360 | 18% |
| S320GD | 320 | 390 | 17% |
| S350GD | 350 | 420 | 16% |
Values according to EN 10346 as compiled by a producer of coated products.
Structural grades from this group are used in thin-walled load bearing components: cold formed profiles, purlins, cassettes and support structures for photovoltaic installations. The type and mass of the coating are parameters independent of the grade in this standard, so a material specification without the coating class remains incomplete.
Cold rolled products for cold forming, EN 10130
The DC group covers cold rolled products without a metallic coating, with a smooth surface and narrow thickness tolerances. A higher number in the designation corresponds to better formability and a cleaner chemical composition. DC06 is characterised by a carbon content not exceeding 0.02 percent, which is the condition for achieving high anisotropy values.
| Grade | Re max. [MPa] | Rm [MPa] | A80 min. | Typical use |
|---|---|---|---|---|
| DC01 | 280 | 270-410 | 28% | bending, drawing, flanging |
| DC03 | 240 | 270-370 | 34% | deep drawing |
| DC04 | 210 | 270-350 | 38% | high drawing requirements |
| DC05 | 180 | 270-330 | 40% | drawn parts with a high degree of deformation |
| DC06 | 180 | 270-350 | 38% | drawn parts of complex geometry, additionally r90 min. 1.8 and n90 min. 0.22 |
Values for skin passed condition, thickness above 0.7 mm, according to EN 10130 and producer catalogues.
In the low and medium forming classes the DC grades functionally overlap with uncoated DX grades. What remains decisive is the surface finish and the corrosion protection of the finished part, because cold rolled sheet is supplied as a material without corrosion resistance, protected only by oil for transport and storage.
General purpose structural steels, EN 10025-2
In the designation S235JR the letter S stands for structural steel, the number for the minimum yield strength for thicknesses up to 16 mm, and the letter code for the required impact properties. For thicknesses below 3 mm S235JR has a tensile strength of 360-510 MPa with a minimum elongation of 26 percent, and S355J2 a tensile strength of 510-680 MPa with a minimum of 22 percent.
| Designation | Minimum impact energy | Test temperature |
|---|---|---|
| JR | 27 J | plus 20 degrees Celsius |
| J0 | 27 J | 0 degrees Celsius |
| J2 | 27 J | minus 20 degrees Celsius |
| K2 | 40 J | minus 20 degrees Celsius |
Requirements according to EN 10025-2.
In thin flat products the impact designation has limited significance. The standard provides that the impact properties of quality JR products are verified only when this has been specified at the time of the order. Requiring an impact test without agreeing it when the order is placed therefore leads to a gap between the expectation of the buyer and the scope of the inspection document.
Hot rolled products for cold forming, EN 10111
The standard covers hot rolled products intended for further cold forming, designated from DD11 to DD14. The most widely used grade, DD11, has a yield strength in the range of 170-360 MPa and a tensile strength up to 440 MPa, with a minimum A80 elongation of 23 percent for thicknesses below 2 mm. The following grades have narrower yield strength ranges and higher required elongation.
This material is used in side panels, frames, housings and agricultural machinery components, that is wherever formability rather than the load capacity of the section is decisive. The surface of a hot rolled product remains covered with mill scale unless the material has been ordered pickled and oiled.
Most common specification mismatches
Several mismatches between the wording of a specification and the actual requirement of the finished part recur in purchasing practice.
1
Treating DX51D and DC01 as equivalent
Both grades are described as materials for bending, while the fundamental difference, the presence of a metallic coating, is left aside. This is decisive in parts used without additional corrosion protection.
2
Over-specified forming class
Using DX54D instead of DX51D, or DC04 instead of DC01, raises the material cost and narrows availability without adding any benefit in bent and roll formed parts.
3
Treating S235JR and DD11 as substitutes
The first is a structural steel with a defined yield strength and impact properties, the second a material intended for cold forming, in which yield strength is given as a range and impact properties are not specified.
4
Specification limited to grade and thickness
Without the coating class and type, the surface finish and the method of protection, the delivered material may differ from technological expectations even though it fully complies with the ordered grade.
Verification of a specification is easier once it is clear what the grade designation itself covers. Surface quality class, dimensional tolerances and the method of protection are governed by separate provisions of the product standards, which is discussed in more detail in the article on second-grade steel sheet defects. The scope of confirmation of mechanical properties depends in turn on the type of document ordered, covered in the article on inspection documents according to EN 10204. The characteristics of downgraded material, in which the grade still matches the order despite manufacturing deviations, are presented in the article on second-grade steel sheet.
Available steel grades, coating types and formats of coils, slit strip and sheets are presented in the HEN-STOL steel sheet offer, with separate pages for galvanized steel sheet, cold-rolled steel sheet and hot-rolled steel sheet.
See how we can help
Send us the specification of the material you currently use: grade, thickness, width, coating class and type, preferred delivery form and batch size. We will verify availability and present the best terms we can offer. If the selected grade turns out to be over-specified, we will indicate a material matching the actual requirements of the part.
Frequently asked questions
What does the designation DX51D mean?
The letter D indicates a flat product for cold forming, the letter X means that the rolling method is not specified and is left to the producer, the number 51 describes the lowest forming class in this group, and the final letter D indicates that the product is intended for continuous hot-dip coating according to EN 10346.
What is the difference between DX51D and DC01?
DX51D is a hot-dip coated product according to EN 10346, that is a material with a metallic coating applied in line. DC01 is a cold rolled product according to EN 10130, without a coating, with a smoother surface and narrower thickness tolerances. The difference determines whether the material is suitable for parts used without additional corrosion protection.
Which grade corresponds to deep drawing?
Among coated products deep drawing corresponds to DX53D and higher grades, among cold rolled products to DC03 and higher. The limit of suitability is set by the geometry of the drawn part rather than by the name of the operation, so the class is selected against the required degree of deformation and the A80 values given for the grade.
What do the letters G and D mean in S350GD?
The letter S stands for structural steel, the number 350 for the minimum specified yield strength in megapascals, the letter G for a flat product within the group of coated structural steels, and the letter D for a product intended for hot-dip coating. The minimum tensile strength of this grade is 420 MPa and the minimum A80 elongation 16 percent.
Can S235JR and DD11 be used interchangeably?
These grades are not equivalent. S235JR is a structural steel with a minimum yield strength of 235 MPa and specified impact properties, DD11 is a hot rolled product for cold forming in which yield strength is given as a range of 170-360 MPa and impact properties are not specified. Any substitution requires a check against the structural requirements of the part.
What should a sheet specification contain besides the grade?
Besides the grade and dimensions a specification should state the coating type and mass, the surface quality class, the finish and method of protection, the delivery form and the required inspection document. The grade designation alone determines none of these parameters, although they decide whether the material performs in the process.
Sources
- EN 10346, Continuously hot-dip coated steel flat products, technical delivery conditions
- EN 10130, Cold rolled low carbon steel flat products for cold forming, technical delivery conditions
- EN 10025-2, Hot rolled products of structural steels, technical delivery conditions for non-alloy structural steels
- EN 10111, Continuously hot rolled low carbon steel sheet and strip for cold forming
- EN 10027-1, Designation systems for steels, steel names
- SSAB, Metal coated formable steels and metal coated structural steels according to EN 10346:2015
- ArcelorMittal, B10 Steels for cold forming, product catalogue
- Salzgitter Flachstahl, Mild non-alloy steels for direct cold forming according to EN 10111