Cold rolled steel coil is the workhorse material behind stamped and drawn parts in appliances, vehicles, furniture and enclosures. The DC grade series gives designers a graduated choice of formability, from basic bending grades to interstitial-free ultra deep drawing steels, so every component can be produced on the most economical specification that still meets its drawing requirement.
What Cold Rolled Steel Coil Is
Cold rolled coil begins as hot rolled coil that has been pickled to remove oxide scale and is then rolled again at ambient temperature. Re-rolling at low temperature produces more exact dimensions and a better surface than hot rolling alone. Strictly speaking, cold rolling applies to flat product reduced between rollers; material that is pulled to size, such as bar or tube, is drawn rather than rolled. Other cold finishing operations such as turning and grinding refine hot rolled stock without changing its basic section. All the grades in this article therefore describe flat product supplied as coil or cut sheet.
Grade by Grade from DC01 to DC07
DC01 - the basic cold forming grade, with carbon content typically up to about 0.12%. It suits simple operations such as bending, embossing, beading and light drawing.
DC03 - a light drawing grade with good elongation, used for moderately shaped parts and reproduction-type forming work.
DC04 - the standard deep drawing grade, suitable for parts that must form reliably in several deformation modes.
DC05 - a higher deep drawing quality for parts with greater forming severity and a tighter limit on wall thinning.
DC06 - a titanium stabilised interstitial-free steel with very high r90 and n90 values, used for the most demanding drawn and stretched parts such as large panels, oil pans and floor pressings.
DC07 - the top grade of the series, an interstitial-free steel for extreme forming where the material must absorb the largest deformation without failure.
Forming capacity increases along the series, so the correct grade is the lowest one that forms the part without splitting. Higher grades are easier to form but softer and more costly, and they are more easily marked by tooling. The cross reference table below converts a requirement expressed in one national system into the grade series used elsewhere.
Equivalent Grades Across Standards
| Grade | EN 10130 numeric | NF A 36-401 | UNI 5866 | JIS G 3141 |
|---|---|---|---|---|
| DC01 | 1.0330 | C | FeP01 | SPCC |
| DC03 | 1.0347 | E | FeP03 | SPCD |
| DC04 | 1.0338 | ES | FeP04 | SPCEN |
| DC05 | 1.0312 | - | - | - |
| DC06 | 1.0873 | - | - | - |
| DC07 | 1.0898 | - | - | - |
Mechanical Properties of the Series
Yield strength falls and elongation rises as the grade number increases, which is why deeper parts call for higher grades. Transverse values for yield strength Re, tensile strength Rm, elongation A80, plastic strain ratio r90 and work hardening exponent n90 are given below.
| Grade | Re MPa | Rm MPa | A80 min % | r90 min | n90 min |
|---|---|---|---|---|---|
| DC01 | 140 - 280 | 270 - 410 | ≥ 28 | - | - |
| DC03 | 140 - 240 | 270 - 370 | ≥ 34 | ≥ 1.3 | - |
| DC04 | 140 - 210 | 270 - 350 | ≥ 38 | ≥ 1.6 | ≥ 0.18 |
| DC05 | 140 - 180 | 270 - 330 | ≥ 40 | ≥ 1.9 | ≥ 0.20 |
| DC06 | 120 - 170 | 270 - 330 | ≥ 41 | ≥ 2.1 | ≥ 0.22 |
| DC07 | 100 - 150 | 250 - 310 | ≥ 44 | ≥ 2.5 | ≥ 0.23 |
Applications and Selection Notes
Appliance and enclosure parts - DC04 and DC05 for wrappers, shells and panels where surface quality and draw depth both matter.
Automotive and transport - DC06 for large panels, fuel tanks and structural pressings with significant deformation.
General fabrication - DC01 and DC03 for brackets, housings and covers that only need bending and light forming.
Coated product - the same grades act as substrate for hot dip zinc coatings when corrosion protection is required as well as formability.
Standard conversion - the Chinese cold forming standard GB/T 5213 covers comparable low carbon grades, so any conversion between systems should be checked against the drawing and the edition of the standard that applies to the order.
FAQ
Q: What is cold rolled steel coil made from?
It is made from hot rolled coil that has been pickled to remove oxide scale and then rolled again at room temperature to reach final thickness and surface quality.
Q: What do the letters DC stand for in the grade name?
The prefix marks the material as a cold forming grade of flat product, and the number ranks its formability within the series, with higher numbers indicating more severe drawing capability.
Q: Do the grades differ in strength?
The tensile strength ranges overlap, but yield strength falls and elongation rises as the grade number increases, because higher grades are produced with lower carbon and interstitial content to maximise ductility.
Q: Why are the highest grades interstitial-free steels?
Removing dissolved carbon and nitrogen stops those elements from pinning dislocations during deformation, which raises elongation and the plastic strain ratio and allows very deep draws without cracking.
Q: Can DC grade coil be supplied oiled?
Yes. A light oil film is applied on request to limit oxidation during storage and shipping, and it can be removed before painting or welding when the process requires a clean surface.
Q: How does grade selection affect press tooling?
Lower yield strength in the higher grades reduces forming load, but softer material shows tool marks more readily, so die clearance and tool surface finish should be chosen together with the grade.
