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How many processes are there for galvanizing? And the advantages and disadvantages of comparison.

Release date:2018-06-28 author: click:

Galvanizing process and advantages and disadvantages:

(1) Wet hot-dip galvanizing

The solvent on the surface of the steel sheet is hot-dip galvanized without being dried (i.e., the surface is still wet) into the zinc liquid whose surface is covered with the molten solvent. The disadvantages of this method are:

a. It can only be galvanized in a lead-free state, and the alloy layer of the plating layer is thick and the adhesion is very bad.

b. The generated zinc slag is accumulated at the interface between the zinc liquid and the lead liquid and cannot be deposited on the bottom of the pot (because the specific gravity of the zinc slag is greater than that of the zinc liquid and less than the lead liquid), so that the steel sheet contaminates the surface by passing through the zinc layer. Therefore, this method has been basically eliminated.

(2) Single sheet steel

This method generally uses a hot rolled rolled sheet as a raw material. First, the annealed steel sheet is sent to a pickling workshop, and the hot-dip galvanized iron sheet on the surface of the steel sheet is removed with sulfuric acid or hydrochloric acid. The steel plate after pickling is immediately immersed in a water tank for galvanizing, which prevents the steel plate from reoxidizing. After pickling, water washing, squeezing, drying, and entering the zinc pot (the temperature is always maintained at 445-465 ° C), hot-dip galvanizing, and then oiling and chromizing. The quality of the wet galvanized products produced by this method is significantly improved, and only has a certain value for small-scale production.

(3) Huilin Law

The production line includes a series of pre-treatment processes such as lye degreasing, hydrochloric acid pickling, water rinsing, solvent coating, drying, etc., and the hood annealing is required before the original plate enters the galvanizing line for galvanizing. This method has a complicated production process and high production cost. More importantly, the products produced by this method often have solvent defects and affect the corrosion resistance of the coating. Further, the AL in the zinc pot is often generated by the action of the solvent on the surface of the steel sheet, and the adhesion of the plating layer is deteriorated. Therefore, although this method has been published for nearly 30 years, it has not been developed in the world hot-dip galvanizing industry.