Why Cold-Rolled Steel Is Harder and Stronger
Cold-rolled strip begins as hot-rolled coil that is pickled to remove oxide and then reduced in thickness at ambient temperature on a tandem mill. Because the steel is deformed below its recrystallisation temperature, dislocations multiply inside the grains and cannot annihilate by diffusion. The result is work hardening: yield strength, tensile strength and surface hardness all rise, while the material keeps a far better surface finish and a much tighter thickness tolerance than the hot-rolled coil it came from. A cold-reduced low-carbon strip such as DC01 typically reaches a yield strength of 140 to 280 MPa against roughly 235 MPa minimum for a hot-rolled structural grade, but it does so with thickness tolerances measured in hundredths of a millimetre rather than tenths.
DC01 in the EN 10130 Cold-Reduced Family
DC01 is the base grade of EN 10130 and is supplied as coil, slit strip and cut-to-length sheet. It is a non-alloy low-carbon steel intended for simple forming operations such as bending, coining, beading and shallow drawing, and it is normally skin-passed to remove the yield-point elongation that causes stretcher strains on formed parts. Its legacy designations remain in daily commercial use, so the following cross-reference is the one most often requested on purchase orders.
| Standard | Designation | Status |
|---|---|---|
| EN 10130 | DC01, material 1.0330 | Current European specification |
| DIN 1623 | ST12 | Withdrawn, replaced by EN 10130 |
| JIS G3141 | SPCC | Commercial quality cold-reduced |
| ASTM A1008 | CS Type B | Commercial quality cold-rolled sheet |
| GB/T 5213 | DC01 | Chinese cold-reduced coil standard |
DC01 versus DC03 and DC04: The Forming Severity Ladder
The DC family is graded by how severely the steel can be formed, not by how strong it is. Each step widens the permitted yield range and raises the guaranteed elongation, which is what allows deeper draws and more complex profiling without splitting.
| Grade | Forming duty | Rp0.2 (MPa) | Rm (MPa) | A80 min (%) |
|---|---|---|---|---|
| DC01 | Simple bending, coining, beading, shallow draw | 140 to 280 | 270 to 410 | 28 |
| DC03 | Deep drawing, difficult profiling | 140 to 240 | 270 to 370 | 34 |
| DC04 | High forming requirements, deep-draw quality | 140 to 210 | 270 to 350 | 38 |
DC04 is a deep-drawing grade of the same family and performs well under every type of deformation, including the high forming requirements of automotive and appliance panels. If a part splits in a DC01 die, the correct response is usually to move up the ladder rather than to increase blank holder force, because the failure is caused by insufficient elongation rather than by insufficient strength.
Surface Finish, Flatness and Thickness Control for CRC Strip
Thickness range: CRC strip is routinely produced from 0.30 mm to 3.00 mm; heavier cold-reduced sections above 3.00 mm are supplied as pickled and oiled hot-rolled material instead.
Surface finish: bright finish for painted parts, matt finish for drawing operations where lubricant retention matters, and a controlled roughness range declared on the inspection certificate.
Flatness and camber: tension-levelled cut-to-length lines deliver the improved and special flatness classes used by laser-cutting and roll-forming customers.
Common sheet formats: 1219 mm x 2438 mm and 1219 mm x 3048 mm, known commercially as 4x8 and 4x10.
Skin-passing: a 0.5 to 1.5% reduction removes the yield-point elongation, stabilises the yield plateau and gives the strip the surface texture needed for painting.
Carbon Steel versus Stainless: Where 316 and Duplex 2205 Fit
Cold-rolled carbon strip and stainless coil are not substitutes, and the price gap explains why buyers ask the question. DC01 and DX51D are non-alloy steels protected by coating or paint. Type 316 stainless, specified under ASTM A240 and EN 10088, contains roughly 16 to 18% chromium, 10 to 14% nickel and 2 to 3% molybdenum, and it resists corrosion through the passive chromium oxide film rather than through a zinc barrier. Duplex grades such as 2205 contain about 22% chromium, 5 to 6% nickel and 3% molybdenum in a two-phase ferritic-austenitic structure, which gives roughly twice the yield strength of an austenitic grade together with better chloride resistance. The lower nickel content of duplex is also the main reason it is often the cheaper of the two on a cost-per-strength basis, even though its alloying is more complex.
Ordering Checklist and FAQ
Specify grade, thickness and its tolerance class, width, surface finish, flatness class, edge condition and oiling state when ordering cold-reduced coil. Adding the application - painted panel, welded bracket, drawn housing - lets the mill confirm whether DC01 is adequate or whether DC03 or DC04 is required.
Q: Why is cold-rolled steel stronger than hot-rolled steel?
Cold reduction deforms the steel below its recrystallisation temperature, so dislocations accumulate and harden the material. Hardness, yield strength and resistance to deformation all increase as a result.
Q: Is DC01 the same as CR4?
DC01 is the EN 10130 designation for cold-reduced commercial-quality low-carbon steel, and it is the grade commonly traded under the workshop shorthand CR4.
Q: What is DC04 used for?
DC04 is a deep-drawing grade with excellent forming behaviour under all deformation types. It suits high forming requirements such as deeply drawn automotive and appliance panels.
Q: What replaced ST12?
EN 10130 replaced the withdrawn DIN 1623 specification, and the designation DC01 replaced ST12. The material number 1.0330 is unchanged.
Q: Is 316 stainless stronger than duplex 2205?
No. Duplex 2205 achieves roughly twice the yield strength of an austenitic 316 grade and offers better chloride resistance, though it needs more careful welding control.
Q: How is cold-rolled strip supplied?
As mill edge or trimmed edge coil, slit strip and cut-to-length sheet in formats such as 4x8 and 4x10, usually lightly oiled to prevent rust in transit.