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Quality Inspection Standards for Galvanized Steel

Mar. 16, 2020

The quality of galvanized steel includes specifications, surface, galvanized amount, chemical composition, shape, machine function and packaging. Manufacturers need to implement these requirements when they are manufactured. The following is a detailed understanding with Galvanized Steel Sheet Manufacturer:


Divided into two kinds of galvanized steel sheet cut into a fixed length and rolled galvanized steel sheet packaging. General metal packaging, lined with moisture-proof paper, and tied with iron waists, the binding is firm, to prevent the galvanized steel plate inside from rubbing against each other.


The relevant product dimensions (such as the following and) all indicate the standard thickness, length and width of galvanized steel sheet and its allowable faults. In addition, the width and length of the board and the width of the roll can also be determined according to the user's request.


General situation: Due to the differences in the treatment methods in the galvanized steel sheet, the general situation is also different, such as the general situation of ordinary zinc flower, fine zinc flower, flat zinc flower, zinc-free flower, and phosphate treatment. Galvanized steel and Galvanized Steel Coil cut to a fixed length must not have disadvantages that affect the use, but the rolled plate allows for some non-deformed sections such as welding parts.

4.Zinc plating amount

Galvanized steel scale value: Galvanized steel is a widely accepted useful tool to imply the thickness of the zinc layer of galvanized steel. There are two types of galvanization on the two sides (equivalent thickness galvanization) and two sides (difference in thickness galvanization). The unit of galvanizing amount is g / m2.

5. Machine function

(1) Tensile test: Generally speaking, as long as the galvanized steel sheet for layout, drawing, and deep drawing has a tensile function request.

(2) Bending experiment: It is an important item to weigh the function of thin plate technology. But the requirements of various national standards for various types of galvanized steel are actually different. Generally, after the galvanized steel plate is bent for 180o, the outer profile must not have a zinc layer to leave, and the plate base must not be cracked and broken.

6. Plate shape

There are two goals to weighing the flat black and white, flatness and sickle. The flatness of the plate and the allowable values of the sickle curve must be delimited.

Galvanized Steel Sheet

Galvanized Steel Sheet

However, Galvanized Steel Sheet is widely used in construction, automobile, home appliances and other industries due to its ideal comprehensive properties such as corrosion resistance, forming, welding and coating, as well as low cost and good appearance. There will be linear protrusions and head-up defects in the production of galvanized steel, which will affect the quality of the product. The customer's use needs to be controlled. So how to control the surface unevenness of galvanized steel?

1. Linear protrusion

The appearance and appearance of linear raised defects generally follow the rolling direction and are distributed in a linear pattern of different lengths. They look like scratch defects. The difference is that the number of linear raised defects is not fixed, and the relative position is compared. fixed. The cause of this defect is due to a defect in the raw material.

Control measures:

(1) Optimize the composition design of the steelmaking process, and focus on adjusting the ratio of manganese and sulfur in molten steel; meanwhile, formulate the cold water quantity system in two seasons to distinguish the interference caused by winter and summer factors.

(2) In the continuous casting stage, select the mold with plating in the upper half without plating.

(3) Strengthen the management of processes and equipment before galvanizing, and try to avoid scratches due to equipment. At the same time, the cold rolling production first considers reducing the large rolling force of the passes, thereby reducing the occurrence of rolling material damage caused by excessive shearing.

2. Headscarf defects

Because it is somewhat like a wrinkle on a person's forehead, it is called a wrinkle. The hot-dip galvanized original sheet has transverse streak defects, the fluidity of the zinc solution, and the formation of Coriolis gas mass during continuous annealing, and other factors are likely to cause the heading defects of the galvanized steel sheet.

Control measures:

(1) Properly increase the temperature of the zinc liquid and the speed of the strip, or reduce the aluminum content in the zinc liquid and increase the height of the air knife to increase the fluidity of the zinc liquid in the air knife area.

(2) Increase the pushing amount of the bending roller to improve the bending effect. Increase the number of yielding areas, reduce the width of the yielding area, and lighten up the lines.

(3) Reduce the tensile elongation, that is, reduce the total amount of plastic deformation.

(4) Reasonably control the strip annealing temperature.

The above is the quality inspection standard of galvanized steel.

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