Cold-rolled low-carbon steel sheet is the starting material for a large share of galvanized, painted and plain flat products used in industry. In the European system these grades are defined by EN 10130, cold rolled low carbon steel flat products for cold forming. The most common grade, DC01, is frequently ordered under the older designation CR4, and the two names refer to the same class of material in most supply chains. This article explains the grade structure, the property differences that matter in practice, and how to specify sheets that will later be galvanized without surprises.
What DC01 means under EN 10130
DC01 is the base forming grade of the EN 10130 series. It is a low-carbon, aluminium-killed or rimmed steel intended for bending, profiling, flanging and simple drawing. For thicknesses above 0.5 mm up to 3.0 mm, EN 10130 requires a yield strength Rp0.2 of 140-280 MPa, a tensile strength Rm of 270-410 MPa and a minimum elongation A80 of 28%. The chemical limits are carbon 0.12% max, manganese 0.60% max, phosphorus 0.045% max and sulphur 0.045% max. Surface quality is classified A and B, and the sheet is normally supplied in a bright, lightly oiled condition.
| Property | DC01 / CR4 | DC03 / CR3 | DC04 / CR2 type |
|---|---|---|---|
| Carbon max | 0.12% | 0.10% | 0.08% |
| Manganese max | 0.60% | 0.45% | 0.40% |
| Yield Rp0.2 | 140-280 MPa | 140-240 MPa | 140-210 MPa |
| Tensile Rm | 270-410 MPa | 270-370 MPa | 270-350 MPa |
| Elongation A80 min | 28% | 34% | 38% |
Where the CR4 designation comes from
CR4 is a legacy designation used in British and continental practice for cold-reduced low-carbon sheet; in most reference tables CR4 maps to DC01, and CR3 maps to DC03. The CR series numbers lower toward better formability, so CR1 and CR2 approximately correspond to the deeper-drawing DC04-DC06 range. When a drawing calls for CR4, ordering DC01 to EN 10130 is normally acceptable, but the contract should state the governing standard explicitly so that mechanical values and tolerances are defined.
DC04 and when to step up from DC01
DC04 is the deep-drawing grade of the same family. Compared with DC01 it has a lower carbon limit of 0.08%, a lower yield range of 140-210 MPa and a minimum elongation of 38%, which translates into better stretchability and less risk of tearing in complex draws. It is the substrate of choice for automotive inner panels, appliance wrappers and parts with deep flanges or tight corners. The price difference between DC01 and DC04 is small relative to the tooling and scrap cost of a failed draw, so for anything beyond simple bends, DC04 is usually the economical choice.
Using these grades as galvanizing substrates
The same chemistry family appears in the galvanized world: a DC01-type base becomes DX51D+Z or DX53D+Z after continuous hot-dip galvanizing, and a DC04-type base maps to DX54D or DX56D. If the final product is to be galvanized, specify the coated grade directly and let the line anneal the substrate, because the coating process changes the temper and the mechanical certificate of the finished coil, not of the uncoated sheet.
Sourcing and verification checklist
State the standard and edition, the grade, the thickness and width tolerance class, the surface quality, and the oiling and packaging requirement. Request the mill certificate before shipment and check that the yield, tensile and elongation values fall inside the EN 10130 ranges for the ordered thickness. For sheets that will be galvanized later, also confirm flatness, because bow and waviness are measured differently on uncoated and coated product and affect line feeding.
Frequently asked questions
Is CR4 exactly the same steel as DC01?
In commercial practice CR4 is treated as equivalent to DC01, but CR4 is a legacy name without a current standard text; to remove ambiguity, order DC01 to EN 10130 and note the CR4 reference in the contract.
Can DC01 be deep drawn?
Only for shallow parts. The minimum elongation of 28% and the yield range up to 280 MPa limit the drawing ratio; for deeper draws, DC03 or DC04 should be selected.
What surface finish is supplied on DC01?
DC01 is normally supplied with a smooth bright surface, lightly oiled to prevent corrosion in transit; surface quality A is the higher class, free of visible defects on the visible face.
Does galvanizing change the mechanical properties of DC01?
The coating itself adds no strength, but the annealing step inside the galvanizing line softens the base; the mechanical values of the coated product are guaranteed against the coated grade standard such as EN 10346, not against EN 10130.
What thickness range does EN 10130 cover?
The standard covers cold-rolled flat products from 0.35 mm to 3.0 mm in its main mechanical tables; thicker material is usually produced to EN 10025 or hot-rolled specifications instead.
How should DC01 sheets be stored before processing?
Store them indoors, flat, with the oil film intact and edge protection in place; condensation under stacked sheets causes surface rust that cannot be fully removed by the galvanizing pickle line without pitting.