What JIS G3141 SPCC-1B and EN 10130 DC01 Actually Cover
SPCC-1B is a commercial-quality cold rolled low carbon steel sheet specified in JIS G3141, the Japanese standard for cold-reduced carbon steel sheet and strip. DC01 is the equivalent commercial-quality grade in EN 10130, the European standard for cold rolled low carbon steel flat products for cold forming. St12 was the earlier German designation for the same quality level under the withdrawn DIN 1623-1 standard, and it is still widely quoted in enquiries and drawings. All three describe a mild, low carbon, uncoated cold rolled sheet supplied in the annealed and skin-passed condition, with good surface finish and good formability for bending, embossing, beading and light drawing.
Cross-Standard Grade Equivalents
| Standard | Designation | Quality / forming level |
|---|---|---|
| JIS G3141 | SPCC-1B / SPCC-SD | Commercial quality, general forming |
| EN 10130 | DC01 | Commercial quality, simple forming |
| DIN 1623-1 (withdrawn) | St12 | Former commercial quality grade, now DC01 |
| BS 1449 Part 1 | CR4 | Commercial quality, broadly equivalent to DC01 |
| ASTM A1008 | CS Type B | Commercial steel, general forming |
The practical message is that SPCC-1B, DC01, St12 and CR4 are interchangeable in most forming operations, but they are not dimensionally or chemically identical. Purchasers should confirm the controlling standard, the thickness tolerance class and the surface finish when swapping one designation for another on an existing dies set.
Chemical Composition Limits
The table below gives the maximum heat analysis values defined for the commercial-quality grades under EN 10130, together with typical commercial-quality limits used for SPCC under JIS G3141.
| Element (max, %) | DC01 (EN 10130) | DC03 (EN 10130) | SPCC (typical) |
|---|---|---|---|
| Carbon | 0.12 | 0.08 | 0.15 |
| Manganese | 0.60 | 0.45 | 0.60 |
| Phosphorus | 0.045 | 0.035 | 0.100 |
| Sulphur | 0.045 | 0.035 | 0.035 |
| Aluminium (min) | 0.020 | 0.020 | - |
Very low carbon and controlled residuals keep the sheet soft and ductile, which is what allows the material to be pressed into automotive and appliance panels without cracking. Note that the carbon limit published for DC03 is 0.08%, not 0.10%; drawings that quote 0.10% for DC03 should be corrected.
Mechanical Properties and Formability
DC01 / SPCC-1B / St12: yield strength approximately 140–280 MPa, tensile strength 270–410 MPa, elongation after fracture 28% minimum. Suitable for bending, embossing, beading and light drawing.
DC03: yield strength approximately 140–240 MPa, tensile strength 270–370 MPa, elongation 34% minimum. Selected when the part needs deeper drawing or more difficult profiling than DC01 can deliver.
DC04 and DC05: progressively higher elongation and plastic strain ratio for severe deep drawing, for example complex automotive panels.
Surface Finish, Delivery Condition and Automotive Use
Sheet of this class is normally supplied annealed and skin-passed, lightly oiled against rust, in either a dull matte finish that takes paint well or a smoother bright finish for visible parts. The designation alone does not fix the finish, and uncoated sheet carries no corrosion protection, so moisture-exposed parts must be painted, phosphated, oiled or galvanized after forming.
Typical automotive applications
Inner body panels, brackets, reinforcements and seat frame components that are painted after assembly.
Oil pans, covers, housings and shrouds produced by press forming and welding.
Structural supports where moderate strength with good weldability is more important than corrosion resistance.
Components that are subsequently hot-dip galvanized or electro-galvanized, where the cold rolled substrate only needs clean formability.
FAQ
Q: Is DC01 the same as CR4?
CR4 under BS 1449 Part 1 and DC01 under EN 10130 both describe a commercial-quality mild cold reduced steel, and in practice they are treated as equivalent, but the controlling standard, tolerances and finish should always be confirmed before substituting one for the other.
Q: What is the difference between DC01 and DC03 steel?
DC01 is intended for simple forming such as bending, embossing, beading and light drawing, while DC03 has a tighter chemistry and higher elongation and is used for deep drawing and difficult profiling.
Q: What does SPCC-1B mean under JIS G3141?
SPCC-1B designates commercial-quality cold rolled low carbon steel sheet under JIS G3141, supplied in a standard surface finish condition; the designation does not by itself define a deep-drawing capability, so harder forming duties call for a higher grade such as SPCD.
Q: Is St12 still a valid designation?
St12 came from the withdrawn DIN 1623-1 standard. It has been replaced by DC01 in EN 10130, but the old name remains common in legacy drawings and should be read as equivalent to DC01.
Q: Can DC01 be used for deep drawing?
DC01 can handle light drawing only. For deep drawing or complex profiles, DC03, DC04 or DC05 should be specified instead, since they offer higher elongation and better plastic strain ratio.
Q: Does cold rolled low carbon steel sheet need a coating?
Yes for any wet or outdoor service. The uncoated surface will rust once moisture is present, so parts are normally painted, phosphated, oiled or galvanized after forming.