The difference between the high quality galvalume steel sheet made in China and the galvanized corrugated board is that the chemical composition of the galvanized layer is mainly 55% aluminum, 43.5% zinc, and 1.5% silicon. The anti-corrosion is mainly provided by aluminum-zinc alloy. However, silicon is also important in that it minimizes the formation of brittle layers during production, and without it, it is not possible to use continuous hot-dip production. The interaction between the substrate and the galvanized layer is very important for the adhesion of the galvanized layer during the production process. Silicon is not used to improve corrosion resistance, but to limit the formation of alloy layers, making the product easy to form. The English logo is AZ. A represents aluminum, Z represents zinc, and AZ is aluminized zinc. As the market matures, the name of aluminum-zinc-plated zinc has evolved into many types: aluminum-zinc-coated, 55% aluminum-zinc, aluminum-zinc steel, and anti-corrosion aluminum-zinc. Due to its unique microstructure, galvanized steel sheet has 2 to 6 time higher corrosion resistance than ordinary galvanized steel sheets.
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Cleaning: compared with the common hot galvanized sheet, the production of high quality Galvalume steel sheet has more stringent requirements on the cleaning degree of the base plate. This is due to the high content of aluminum, high temperature, easy oxidation of aluminum and the generation of zinc steam when hot-plated aluminum-zinc alloy.
Therefore, in order to ensure the production of adhesive PZN alloy plating plates, cleaning is generally done outside the furnace, that is, electrolytic degreasing cleaning is set before the annealing furnace.
Annealing: The high quality Galvalume steel sheet made in China annealing with ordinary hot galvanized sheet s than there are two problems should be considered: is to how to realize the online LCAK steel aging treatment, because of its best-of averaging temperature is 300 ~ 350 ℃, and the strip into the zinc pot temperatures higher than 550 ℃.
Some foreign manufacturers in furnace H2 content increased to 40% ~ 60%, and the furnace nose at zero temperature control in 523 hot dips: because A – eta alloy Xing point is higher, so the solution temperature is higher than ordinary galvanizing temperature, the best temperature range is 620 ~ 650 ℃.In order to obtain a better coating adhesion, lambda zinc pot temperature than about 50 ℃ low temperature.
In order to refine the rich aluminum dendritic structure, reduce the interdendritic rich zinc of the volume fraction of grain, in order to improve the coating corrosion resistance (aluminum-rich dendritic crystal small, small gap between crystal, interdendritic is smaller than the grain size of zinc-rich and fine in coating), need fast cooling after plating, the cooling speed of 10 ~ 30 ℃ s general requirements.
Test conditions: placed in relative humidity is 100% x 49 + / – 1 ℃ environment, and check the surface change test conditions: smoke by 55 ℃ environments placed 22 hours to 2 hours and then dry processing 2: Salt spray test, test method will be subject to ASTMB117-73.
The surface is a uniform AZ – ha crystal flower. The surface of the coating layer is solid dendrite crystal, and the dendrite part is the compound of protective effect. Therefore, the remarkable performance of low-cost galvalume steel plate, called G for short, is excellent corrosion resistance and thermal reflection, so the high quality Galvalume steel panel has excellent corrosion resistance at high temperature.
GL board allowed in 3 ℃ working environment for long-term use of surface evenly distributed Azr jin jing to spend and therefore has a good decorative appearance. However, in the process of storage and transportation, the low-cost Galvalume steel plate is prone to corrosion, resulting in white rust, black spots, and other defects. In addition, GL has good performance.
1. The building industry: instead of the hot galvanized sheet is used, such as oil, such as the car roof, wall, waterproof board + pieces of a bay and iron + 3 know the bottom board, extreme pressure lining board.
2. Household appliances industry: bread ovens, refrigerators, air conditioners, stove, oven, heat exchangers and other 4 industrial instrumentation, heater, vending machines, flexible parts, and industrial refrigeration cabinets, etc.
Coating corrosion mechanism ° H < 5: dissolve active zone, is rich with recent early phase, and the dissolution of zinc soon transition to A and zinc solution PH = 6 ~ 9 ° had better corrosion resistance, the destruction of the alloy coating is mainly due to the rich zinc phase PH = 10 ~ 11: good corrosion resistance time zone, wealthy when zinc phase solubility may be accompanied by Apart and A phase of dissolved Xia H > 12: A and zinc alkaline solution area.
According to the performance design of high quality Galvalume steel panel, experimental samples were used to process some fixed hooks of 120Q DX51, 10gm2, surface finish, and chrome-free passivation.
Failure coating (that is, not burned by the flame) of the plate in the processing process, mold extrusion at the plating and surface coating are damaged, but still remain.
In addition, Shandong Hengze New Material Co., Ltd. produces high quality Galvalume steel sheet made in China. Welcome to wholesale GL steel sheet if you are interested in low-cost Galvalume steel plate.