The hot-dip galvanized steel sheet is based on cold-rolled steel sheets of various strength and thickness specifications, and is hot-dipped with a layer of AL-ZN aluminum-zinc alloy coating on both sides. About 55% AL aluminum, 43.5% ZN zinc, 1.6% Si silicon. It combines the physical protection and high durability of AL with the electrochemical protection of ZN. In addition, the surface has a highly decorative bright silver-gray color and a fish scale pattern with a standard, and has a three-dimensional embossed feeling.
The two important elements of the plated sheet are zinc, aluminum, aluminum-zinc, three alloy substances. Zinc is generally represented by Z. Z is the abbreviation of Zinc in English. For example, the zinc content of Z80 surface is 80 grams per square. Z100 means the galvanized content is 100 grams per square, and so on. The number after Z means the average coating content of three points on both sides of the galvanized steel coil in grams per square. The general materials of hot-dip galvanized spot on the market are: Z80, Z100, Z120, Z140, Z180, Z275, etc. Aluminum is represented by A. A is the abbreviation of English Aluminum.
Aluminium-zinc compounds are added together with Z and A. Such as AZ150. Among the galvanized labels, such as AZ100, it means that the content of galvanized is 100 grams per square, AZ70 is 70 grams of galvanized per square, and AZ150 means that the content of galvanized is 150 grams per square. The stock materials of galvanized sheet coils on the market are generally: AZ50, AZ70, AZ100, AZ150, AZ180, AZ200.
The hot-dip 55% Al-Zn alloy steel plate has no rust after 20 years, but the relative galvanized sheet takes about 10 years, the 4% Al-Zn steel plate takes about 10 years, and the 7% Al-Zn steel plate takes about 9 years to rust. Calculated from the measured value of corrosion weight loss, it can be found that the corrosion resistance of 55% aluminum-zinc alloy steel plate can reach more than 50 years.
1. Characteristics of hot-dip galvanized steel sheet
1. Good formability (Machinability), meeting the requirements of roll forming, bending and other forms of processing.
2. Excellent thermal resistance, ordinary hot-dip galvanized products are usually used at a temperature not exceeding 230 °C, and will change color at 250 °C, but the galvanized sheet is different. use.
3. Super high reflectivity, the ability of aluminized zinc to reflect heat and light is twice that of hot-dip galvanized steel. The reflectivity is greater than 0.70, which is better than 0.65 specified by EPA ENERGY STAR. It is an ideal building material for energy saving.
4. Excellent corrosion resistance (Resistance to corrosion), galvanized steel sheet has excellent corrosion resistance than hot-dip galvanized steel sheet of the same thickness, under the premise of the same thickness and the same zinc layer content, the service life is the same as that of ordinary galvanized steel. 2-6 times the steel plate.
5.The coating of galvanized steel sheet has a good electrochemical protection effect on the steel sheet, and the electrochemical effect is analyzed as follows：
An electrochemical protection reaction occurs at the defect:
Anode reaction: ZN-ZE=ZN2+ (the coating loses electrons, sacrificing dissolution)
The cathode should be: FE+2E=FE (iron gets electrons and is protected)
2. Experiment and test of galvanized steel sheet
1. Large steam exposure test of galvanized steel sheet
2.The salt spray test of the galvanized sheet, the salt spray test of the galvanized sheet is up to 5000 hours/hours, the test results of the galvanized steel sheet under the condition of different zinc layer content are as follows：
3. Fourth, the use of galvanized steel sheet
Precautions for use
1. Use galvanized steel sheets with caution under the use conditions of alkaline medium (strong alkaline introduction is prone to chemical reaction with aluminum medium)
2. The roof of the building with galvanized steel plate should have a certain slope, which is conducive to drainage and avoids aggravation of corrosion (the minimum slope is not less than 10 degrees)
3. Avoid direct contact with warm cement and wet wood, lead, copper, graphite.
4. Cut edge boards should be used as much as possible to avoid cutting on site. Expose the incision to air.
5. During processing and stacking, the fingerprint-resistant surface film should be prevented from turning black due to moisture and high temperature.
6. For the galvanized steel sheet used for foam bonding, a small batch test should be carried out when it is used for the first time to prevent poor bonding performance.
7. It is not recommended to use alcohol-based solvents for wiping and cleaning on the surface. If you need to use it, please conduct a small sample test to avoid damage to the surface coating.
Scope of use
Galvanized steel sheet is widely used in construction industry, home appliance industry, industrial installation industry, electrical cabinet, cable tray. Such as
Roofs, exterior walls, color-coated substrates, garage doors, fences, shutters, ventilation ducts, etc. of civil and industrial buildings.
Industrial instruments, electrical control cabinets, industrial freezers, vending machines, refrigerators, etc.