Galvanized packaging solutions with surface defects

Galvanized packaging with the solution of the surface defects in galvanized packaged with classes of dot grain distribution on the surface, traditionally known as zinc grains. Zinc granule defects can be roughly divided into two kinds: one kind is strip surface adhesion of granular, up and down at the local increased the zinc layer thickness, causing surface rough, both neither is beautiful and is harmful to use commonly known as zinc grains. Tianjin galvanized packaged with a rough surface there are two kinds of forms, one of particles larger zinc granule, ingredients are mainly iron - Zinc compounds, i. e. , bottom slag, the cause of this defect is too much zinc pot bottom slag buoyancy, adhering to the surface of a steel plate. Second particles smaller zinc granule, the ingredients are mainly iron - Zinc - Aluminum compounds, which is free of slag, the cause of this defect is free of slag in zinc pot stick to the steel plate surface caused by too much. The solution: ( 1) The reasonable control of zinc liquid temperature 450 ℃, 480 ℃, 470 ℃ and zinc strip into the pot temperature - 490℃。 The former is the purpose of minimizing the strip surface iron solubility, which is accelerating the formation of the F2AL5 layer. ( 2) Strict control of chemical composition in liquid zinc, zinc pot add alloy ingot, reasonable to ensure the percentage content of zinc liquid Al 0. 18 ~ 0. 22%. Its purpose on the one hand is the stability of the zinc liquid ingredients in favor of the formation of F2AL5 layer, on the other hand is the supersaturated liquid zinc iron first combined with sufficient quantity of aluminum into the iron - Zinc - Aluminum compounds, which is free of slag, in order to reduce the formation of slag. ( 3) Improve material surface cleanliness, reduce downtime. Improve material surface cleanliness is to minimize the strip surface in normal production into zinc pot 'dirt'. Number of downtime to a great extent, decide how much to zinc liquid fe content, due to the annealing furnace without strip down anti-oxidation function, a large number of oxidation strip surface in the furnace after downtime, and after the car was to the zinc pot, the zinc liquid fe content increases rapidly. Reduce downtime amount of time and is the fundamental way to solve the problem. ( 4) Slag clean up the table, and regular cleaning of bottom slag in a timely manner. Another is the production of 1. More than 4 mm galvanized sheet, in on both sides of the strip of zinc grain of defects. The cause of this defect is mainly due to the low speed of unit, zinc liquid flows into zinc pot is more focused on the edge, the edge cooling fast, strip and the gas nozzle is not parallel and is concave to causes such as the thick edge easy. Zinc granule defects. Usually existed in liquid zinc, there are many free of slag and a small amount of slag, in the right condition better production liquid zinc liquid, attached to the free surface of strip steel slag and slag under the effect of air blade air scour is often rushed back to zinc pot, when the liquid zinc liquidity is not good, air blade air scour is abate, large free of slag or bottom slag flow gathering effect, when a zinc granule parked in a position through the location the liquid zinc in zinc slag can produce, from small to large form a larger zinc grains.