Prepainted Steel Sheets—-Introduction of Base Metals
The substrates of color-coat boards can divide into cold-rolled substrates, hot-dip galvanized substrates, electro-galvanized substrates, and hot-dip galvanized aluminum-magnesium substrates.
A. Cold rolled substrate
The color-coated sheet produced from the cold-rolled substrate has a smooth and beautiful appearance and has the processing performance of the cold-rolled
sheet: However, any small scratches on the surface coating will expose the cold-rolled substrate to the air, making the exposed area very Red rust will form quickly.
Therefore, such products can only be used for temporary isolation measures that are not demanding and as interior materials.
B. Hot-dip galvanized substrate
In addition to the protective effect of zinc, the hot-dip galvanized color-coated sheet also has the function of insulation protection and rust prevention on the surface,
and the service life is longer than that of the hot-dip galvanized sheet. The zinc content of hot-dip galvanizes substrates are generally 180g/m2 (double-sided),
and the maximum galvanize amount of hot-dip galvanize substrates for building exteriors is 275g/m2 (double-sided).
C. Hot-dip galvanized aluminum substrate
A hot-dip aluminum-zinc steel plate (55% AI-Zn) use as the color-coated substrate. The amount of aluminum and zinc usually 150g/m2 (double-sided).
The corrosion resistance of the hot-dip galvanized sheet is 2 to 5 times that of the hot-dip galvanized sheet.
Continuous or intermittent use at temperatures up to 490°C will not severely oxidize or produce scale.
The ability to reflect heat and light is twice that of galvanized steel, and the reflectivity greater than 0.75 is an ideal building material to save energy.
D. Electro-galvanized substrate
The zinc content is usually 20/20g/m2, so this product is not suitable for outdoor use to make walls, roofs, etc.
But because of its beautiful appearance and excellent processing performance, it can be mainly used in home appliances, audio, furniture, interior decoration, etc.
E. Hot-dip galvanized aluminum-magnesium substrate
Zinc-aluminum-magnesium coating steel plate is to add a certain amount of trace elements, such as aluminum and magnesium,
to the existing hot-dip galvanized or hot-dip aluminum-zinc coating.
Moreover, the results of the published accelerated laboratory experiments and outdoor exposure experiments show that increasing the content of
Al and Mg within a certain range will increase the corrosion resistance of the steel plate by tens to ten times.
Another major advantage after adding magnesium is to improve the corrosion resistance of the cutting edge of the steel plate.
The zinc-based corrosion products containing magnesium will cover the cut surface to protect the cut.