DC05 is the extra deep drawing grade of the EN 10130 family of cold-rolled steels, with better formability than DC01, DC03 and DC04. When the part also needs corrosion resistance, the base coil is coated and supplied as DC05+Z for hot-dip galvanizing or DC05+ZE for electro-galvanizing. The base steel is tested to EN 10130, the hot-dip coating to EN 10346 and the electro coating to EN 10152, and the marking DC05+Z or DC05+ZE tells the buyer exactly which product route was used. This article sets out the performance data and the process.
Base Grade DC05: Composition and Mechanical Properties
| Item | DC05 value per EN 10130 |
|---|---|
| Carbon, max % | 0.06 |
| Manganese, max % | 0.35 |
| Phosphorus, max % | 0.025 |
| Sulphur, max % | 0.025 |
| Yield strength Rp0.2 (MPa) | 120 - 180 |
| Tensile strength Rm (MPa) | 270 - 330 |
| Elongation A80 (min %) | 36 |
| Plastic strain ratio r90 (min) | 1.7 |
| Strain hardening exponent n90 (min) | 0.20 |
The low yield strength and high r90 and n90 values are what make DC05 an extra deep drawing grade: it flows instead of thinning, and strain distributes evenly before local necking, so complex curved surfaces draw without cracking, wrinkling or necking, which directly lowers stamping scrap rates. The same forming indicators survive galvanizing because the coating process is designed not to damage the base structure.
Coating Systems: Hot-Dip Z and Electro ZE
| Coating type | Designation | Coating mass (g/m2, both sides) | Surface roughness | Typical corrosion performance |
|---|---|---|---|---|
| Hot-dip, EN 10346 | Z60 to Z275 | 60 - 275 | Ra up to about 2.5 microns | Strong; in neutral salt spray (ISO 9227) red rust appears only after several hundred to more than one thousand hours depending on coating mass |
| Electro, EN 10152 | ZE25 / ZE50 | 10 - 50 | Ra up to about 1.0 micron | Moderate; requires passivation, suited to indoor service |
Hot-dip zinc is metallurgically bonded to the steel and gives the strongest protection, with Z60, Z100, Z140, Z180, Z200 and Z275 as the standard classes. Electro-galvanized zinc is thinner but far smoother, which makes ZE the choice for visible precision parts, and it is normally supplied with a passivation layer, either chromate or chromium-free.
Why Choose DC05 Galvanized Coil
The grade exists to resolve the conflict between protection and processability. Ordinary galvanized coils with thick, hard coatings can shed zinc or powder at the bend line during severe stamping; DC05+Z avoids this because the soft base deforms under the coating, and for the most severe draws a thinner class such as Z60 or Z100 is specified. The base surface quality of DC05 is available as class FB (no visible defects) or FC (minor defects permitted but covered by paint), so after galvanizing the coil can be used bare or directly painted without extra polishing. On well-run production lines the mechanical consistency of the DC05 base is also excellent, with yield strength fluctuation held to roughly 10 MPa within a coil, which prevents dimensional scatter in stamping. Against bare cold-rolled steel, the zinc layer multiplies corrosion resistance by roughly five to ten times in atmospheric service.
Production Process
The base plate is made by cold rolling hot-rolled pickled coil in multiple passes with a reduction ratio of about 40 to 60 percent, followed by recrystallization annealing in a continuous annealing furnace at 700 to 800 degrees Celsius, which removes cold-working stress and restores the soft, ductile ferrite structure, then temper rolling for surface and shape control. For hot-dip galvanizing, the annealed strip is cleaned, pickled, reduced again at 850 to 900 degrees Celsius and passed through a zinc bath at 450 to 460 degrees Celsius; air knives purge excess zinc to set the coating mass, and the strip cools to form the zinc-iron alloy layer with the pure zinc top layer. For electro-galvanizing, the strip is cleaned, pickled and plated in an electrolytic bath, with coating mass controlled by current density and line speed, then passivated. Both routes finish with stretching and leveling for flatness, optional skin passing and surface treatment, then coiling and packaging.
Application Fields
The home appliance industry is the core consumer: refrigerator liners and door panels drawn to deep cavities, washing machine drums, air-conditioner evaporator covers, microwave oven liners and electric kettle bases, where complex surfaces must form without cracks and the coated surface must look good without painting. The automotive sector uses DC05+Z for interior parts such as instrument-panel brackets and door trim panels, and small exterior parts such as mirror brackets and wiper bases, where the coating replaces post-painting. Electronics and light industry use DC05+ZE for router housings, printer consumable boxes and precision hardware such as lock panels, where the smooth surface prints or paints directly. Medical device casings and high-end furniture hardware complete the picture, with low impurity levels, high surface quality and dimensional stability after stamping as the common requirements.
Frequently Asked Questions
What does DC05+Z mean? DC05 is the extra deep drawing grade of EN 10130, and +Z means the coil is hot-dip galvanized to EN 10346 with a coating class such as Z60 to Z275.
What is the difference between DC05+Z and DC05+ZE? DC05+Z is hot-dip galvanized with a thick, metallurgically bonded coating and strong corrosion resistance; DC05+ZE is electro-galvanized to EN 10152 with a thinner, smoother coating, better for visible indoor parts.
Does galvanizing reduce the formability of DC05? The base properties are retained, but very thick zinc coatings can powder at sharp bends. For severe deep drawing, specify a thinner class such as Z60 or Z100 to keep the coating intact.
What zinc coating should be chosen for a deep-drawn outdoor part? Balance formability and protection: Z100 to Z140 suit most drawn outdoor parts, while Z275 is preferred when the environment is aggressive and the draw severity is modest.
Is DC05 the same as DC06? No. DC06 has even lower carbon and higher r90 and n90 values, making it the ultra deep drawing grade; DC05 is the extra deep drawing grade one step below and more economical.
How is corrosion resistance verified? Coating mass is verified by weighing per the product standard, and corrosion behaviour is characterized in neutral salt spray per ISO 9227; the time to red rust increases with coating mass.