Galvanizing process is the key process in galvanizingDegree control, zinc immersion time control, the use of galvanized lifting equipment is the main galvanized requirementsThe digging part.
Continuous hot galvanizing of strip steel by continuous annealing.Annealing process is the key to the production of hot-dip galvanizing products of high strength steel such as dual-phase steel, which greatly affects the enrichment of elements such as Mn and Si on the surface of the steel plate.The annealing process of galvanized steel sheet usually includes preheating, heating, heating and cooling.Preheating strip steel by heating waste gas can not only save fuel, but also avoid deformation of strip steel due to too fast heating rate.The cooling process of some units adopts the sub-cooling method of slow cooling first and fast cooling later, which can not only avoid the poor shape of the plate caused by too fast cooling speed, but also meet the cooling speed requirements of high strength steel such as dual-phase steel.Some manufacturers also set up equalization sections after the cooling sections to provide a buffer area between the galvanizing and cooling sections so that the strip has a better shape and a more uniform temperature into the zinc-steel galvanizing to improve the quality of the galvanizing.In addition, roller design of annealing furnace, internal annealing, fire atmosphere and dew point control, internal tension control and surface spraying of annealing furnace roller are also the focus of research on hot-dip galvanization annealing process.& nbsp4 alloying process alloying refers to let the pure zinc coating of hot dip plating coating under the 450-550 ℃ immediately diffusion annealing, obtain the iron content is between 7% ~ 15% zinc alloy plating process.The main factors influencing the alloying include the content of available aluminum in zinc liquid, the temperature of zinc pot, the temperature of adding zinc to steel, the temperature of alloying, the speed of strip, the chemical composition of substrate and the thickness of the coating.High quality coating of alloying products, often want to between steel plate and coating without teeth, "phase (F3Zn10), coating surface does not contain a large number of columnar phase b (FeZn 13). It needs to choose the appropriate alloying coating annealing process, the heating rate, soaking time and cooling rate on strictly controlled. Alloying technology in China is relatively weak, coating powder or flake is seen during stamping defects, urgent need to systematically study of alloying technology, especially the phase structure of the coating and its effect are studied. & nbsp5Leveling process, to eliminate strip yield platform, access to good strip flatness and appropriate strip surface roughness, hot galvanized steel sheet, to the line is flat and level. Smooth process parameters including thrust force, bending force, li ping entry tension peace, export tension. In improving the strip shape and improve the quality of the strip surface is obviously better than the four-roll temper mill roller leveler. At present, Japan has developed a silver can be replaced with different work roll diameter of four-roll temper mill, it can better control of different specifications and grade of steel galvanized products of flatness and surface roughness.. Galvanized sheet surface roughness control is one of the key technologies in the high quality of galvanized products,At present mainly to roughen leveling roll roll surface method and its parameters and formation parameters are studied, such as another temper mill work roll roll diameter size and roll surface roughness and so on, also has effect on the product surface coarse accuracy. Among them, in terms of roller surface roughen, shot peening roughen and edm roughen the most widely used, laser roughen due to the long period and too high cost, seldom used, and chrome plated roughen and electron beam roughen more research in recent years, rapid development, but not yet popular. In addition, the flat roller sticky zinc problem has always been a problem in high surface quality of galvanized products, need to make the necessary improvements to temper mill equipment, also can add in flat desalting water cleanerPost-treatment technology. & nbsp6 post-processing including passivation, phosphating and coating oil. Through the passivation treatment, can improve gloss, the surface of the galvanized layer structure and improve the corrosion resistance and service life of the galvanized layer, and can improve the adhesion strength of the coating and base metal. The main using chromium passivation treatment, acid salt, clock in the clock solution to add some activator, such as fluoride, phosphate or sulfate, make get thicker after passivation