Common steel grade base plates and coatings for color steel plates
Color steel plate production process
Color steel plate (also known as color plate or color-coated steel plate) is a product made from cold-rolled steel plate and galvanized steel plate as the base material. After surface pretreatment (degreasing, cleaning, and chemical conversion treatment), it is continuously coated with paint (roller coating metho
d), and then baked and cooled.
Common steel grades for color steel plates
For buildings, the load-bearing capacity (wind load, snow load, construction personnel and machinery), the span of the building, the design of purlin spacing, etc. all rely on the strength of steel plates. For color-coated and aluminized zinc plates used in building maintenance structures, there are corresponding standards. Such as ASTM653 and ASTM792 from the United States, JISG3302 and JISG3321 from Japan, EN10215 and EN10147 from Europe, etc. It is classified by major steel types into CQ (common commercial grade), DQ (general stamping grade), HSS (high-strength structural steel), and FH (all-hard steel).
Common base plates for color steel plates
(1) Cold-rolled base plate
The colored plates produced from cold-rolled base plates have a smooth and beautiful appearance and possess the processing performance of cold-rolled plates. However, any minor scratch on the surface coating will expose the cold-rolled substrate to the air, causing red rust to form quickly at the exposed iron areas. Therefore, such products can only be used for temporary isolation measures with low requirements and as indoor materials.
(2) Hot-dip galvanized substrate
The product obtained by coating organic coatings on hot-dip galvanized steel plates is called hot-dip galvanized color-coated steel plates. In addition to the protective effect of zinc, the organic coating on the surface of hot-dip galvanized color-coated steel sheets also plays a role in isolation and protection, preventing rust, and has a longer service life than hot-dip galvanized steel sheets. The zinc content of hot-dip galvanized base plates is generally 180g/m2 (on both sides), and the maximum galvanizing content of hot-dip galvanized base plates used for exterior buildings is 275g/m2.
(3) Hot-dip aluminized zinc substrate
According to the requirements, hot-dip aluminized zinc steel plates (55%AI-Zn and 5%AI-Zn) can also be used as color-coated base plates.
(4) Electroplated zinc substrate
The product obtained by coating organic paint on electro-galvanized sheet as the base material and baking it is called electro-galvanized color-coated sheet. Due to the thin zinc layer of electro-galvanized sheet, the zinc content is usually 20/20g/m2. Therefore, this product is not suitable for outdoor use in making walls, roofs, etc. However, due to its beautiful appearance and excellent processing performance, it can mainly be used in household appliances, audio equipment, steel furniture, interior decoration, etc.
Classification codes for the base plates of color steel plates
(1) Structural classification code: Z- Normal zinc flower: Zinc flowers obtained by crystallization at a normal cooling rate and can be used for general purposes. X- Small zinc flower: The cooling rate is specially controlled, and the size of the zinc flower is smaller than that of normal zinc flowers, suitable for painting and other occasions where normal zinc flowers do not meet the requirements. GZ- Finish Zinc Flower: The small zinc flowers have undergone finish treatment and are suitable for deep drawing and ultra-deep drawing processes as well as applications with low surface roughness requirements.
(2) Processing performance code: PT- General purpose, JY- Mechanical Locking, SC- Deep Drawing, CS- Super Deep drawing, JY- Structure.
(3) Zinc coating weight code: Z100, Z200, Z275; The weight of the galvanized coating refers to the total amount of zinc contained on both sides of the steel plate, expressed in grams of zinc per square meter of steel plate (g/m ²), for example, Z100 indicates that its zinc content is not less than 100g/m ².
Types of base plate coatings for color steel plates
According to the coating layer, the coatings produced by the hot-dip galvanizing process can basically be classified into the following six types:
(1) GI (Pure zinc coating)
(2) GA (Zinc-iron alloy coating)
(3) 55%Al-Zn (aluminum-zinc coating) (GALVALUME);
(4) 5%Al-Zn (zinc-aluminum coating,GALFAN);
(5) Aluminizing (aluminum plating), aluminum plating can be further divided into two categories: one is pure aluminum plating, and the other is aluminized silicon products.
(6) Zinc-aluminum-magnesium products, new types of coated zinc-aluminum-magnesium products in recent years, such as Zn-5Al-3Mg. Zinc-aluminum-magnesium is a series of products that can include different Mg and Al contents.
