Cold Rolled Coil and Hot Rolled Coil: Where Each Product Belongs
CRC cold rolled coil is made by pickling hot rolled coil and then reducing it at room temperature on a cold rolling mill, followed by annealing and temper rolling. The process costs more energy and more passes than hot rolling, and that is reflected in the price per tonne, but it delivers a smooth surface, a gauge tolerance measured in hundredths of a millimetre and forming behaviour that hot rolled material cannot match. HRC hot rolled coil is supplied essentially as rolled, from about 1.2 mm up to 25 mm and beyond, and it is the economic answer wherever the part is structural, is welded rather than stretched, and will not be judged on appearance.
In practical terms, cold rolled coil is the input for exposed panels, doors, appliance skins and painted architectural parts, while hot rolled coil feeds beams, chassis members, brackets and general fabrication. A catalogue that lists CRC and HRC side by side is not offering alternatives for the same job; the two products serve different stages of the same supply chain.
The DC Grade Ladder and Its Cross-Standard Equivalents
The DC series of EN 10130 is the European drawing quality family, and the same steel appears under different names in other systems. DC01, material number 1.0330, is the general purpose grade; in the Japanese system it corresponds functionally to SPCC of JIS G3141, in the American system to ASTM A1008 CS Type B, and in the British trade it has long been sold as CR4, where CR stands for cold reduced and 4 indicates the quality level.
| Grade | Nearest cross-standard equivalent | Forming severity | Typical parts |
|---|---|---|---|
| DC01 | SPCC, ASTM A1008 CS Type B, CR4 | Simple bending, beading, shallow drawing | Panels, brackets, enclosures |
| DC02 | SPCD (JIS G3141), CR3 / CR4 range | Moderate drawing | Housings, covers, trays |
| DC03 | SPCE (JIS G3141) | Deep drawing and difficult profiling | Sinks, bowls, deep covers |
| DC04 | SPCF (JIS G3141) | High forming requirements | Complex stamped automotive and appliance parts |
Because the naming systems are not identical, an order should always state the standard as well as the grade. A request for drawing quality sheet without a standard reference can be met with a product that satisfies the name but misses the required elongation and surface class.
Structural Grades and Coated Products in the Same Catalogue
Structural and coated products appear alongside the drawing grades because they serve the same fabricators. SS400 of JIS G3101 is a hot rolled structural steel with a minimum yield strength of 245 MPa and a tensile range of 400 to 510 MPa, and its elongation minimum depends on thickness, running from 21 percent for thin sections down to 17 percent for thicker ones. It is the JIS counterpart to EN 10025-2 S275JR and close in intent to ASTM A36 plate, and it is chosen where load carrying capacity is the governing requirement rather than formability.
The comparison with a drawing grade is instructive: S235 or SS400 is designed to guarantee a minimum strength for structural duty, whereas DC01 and DC04 are designed with a capped yield strength so that the material will stretch before it fractures. Mild steel strip that is subsequently hot dip galvanised is sold as GI, and when a paint system is applied over the zinc coating the result is PPGI, prepainted galvanised iron. If the substrate is an aluminium-zinc coating instead of pure zinc, the prepainted product is PPGL. All three keep the forming behaviour of the base steel while adding corrosion protection and, in the prepainted case, a finished decorative surface.
Coating Mass and Surface Reference
Coating designations state the total mass of coating applied to both sides of the sheet, which is the only dependable way to compare corrosion performance between suppliers.
| Coating | Total coating mass | Approximate thickness per side | Service environment |
|---|---|---|---|
| Z100 | 100 g/m² of zinc | About 7 µm | Indoor and lightly sheltered parts |
| Z275 | 275 g/m² of zinc | About 19 µm | Outdoor roofing, cladding and ducts |
| AZ150 | 150 g/m² of aluminium-zinc, 55 % aluminium, 43.4 % zinc and 1.6 % silicon | About 20 µm | Roofing and panels needing heat reflectivity |
The aluminium-zinc coating used for AZ150 combines the barrier protection of aluminium with the sacrificial protection of zinc, which gives it better heat resistance and edge protection than an equal mass of pure zinc in many external applications. It is a different coating chemistry, not simply a heavier version of the zinc coating.
Ordering Checklist for Coil and Sheet
State the base grade and the standard, for example EN 10130 DC01 or JIS G3141 SPCC.
State the coating type and coating mass separately, because Z275 and AZ150 behave differently in the same environment.
Specify thickness, width, and whether thickness tolerance is measured at the edge or at the centre of the strip.
Define the surface condition: spangle type, skin passed or not, oiled, chromate passivated or anti-fingerprint treated.
Confirm coil inner diameter, outer diameter and maximum unit weight so that the material matches the decoiler on site.
For prepainted coil, add paint system, colour code, gloss level and the requirement for a strippable protective film.
Frequently Asked Questions
Q: What is the difference between DC01, DC03 and DC04 steel?
The grades describe increasing formability. DC01 suits simple forming such as bending, embossing, beading and shallow drawing, DC03 suits deep drawing and difficult profiling, and DC04 suits the most demanding forming work.
Q: How does DC01 compare with a structural grade such as S235?
S235 and SS400 guarantee a minimum yield strength for load bearing duty, while DC01 has a lower design strength and is intended for parts where detailed shaping matters more than structural capacity.
Q: What is DC03 steel used for?
DC03 is a mild low carbon cold forming grade with excellent deep drawing capability under all types of deformation, so it is used for drawn housings, bowls and profiled covers.
Q: Is CR4 the same as DC01?
CR4 is the British trade description of the same general purpose cold reduced mild steel that EN 10130 calls DC01. The trade name indicates cold reduced strip at quality level 4.
Q: What does SS400 mean?
SS400 is a JIS G3101 structural steel with a minimum yield strength of 245 MPa and a tensile strength range of 400 to 510 MPa, supplied mainly as hot rolled plate, strip and sections.
Q: What is the difference between GI, PPGI and PPGL?
GI is hot dip zinc coated steel, PPGI is that galvanised steel with a paint system applied on top, and PPGL is prepainted steel whose substrate carries an aluminium-zinc coating instead of pure zinc.
Q: Why is cold rolled coil more expensive than hot rolled coil?
Cold rolling requires pickling, multiple cold reduction passes, annealing and temper rolling, and those extra steps raise the conversion cost while delivering a better surface and tighter gauge tolerance.