How to distinguish the quality of Dalian galvanized coil

Electrochemical and physical mechanical tests can be carried out on galvanized coils to obtain electrochemical behavior and physical performance data; For example: adhesion, corrosion resistance, coating thickness, etc., depending on the specific application requirements.

Supplement: Quality inspection standard of galvanized steel plate:
According to production and processing methods, galvanized steel sheet can be divided into the following categories [1]: hot-dip galvanized steel sheet (commonly known as galvanized iron sheet), electro-galvanized steel sheet, single-sided or double-sided differential thickness galvanized steel sheet, alloy composite galvanized steel sheet, etc. In addition to the above, there are color galvanized steel sheet (commonly known as color plate), printed coated galvanized steel sheet, PVC laminated galvanized steel sheet, etc. In addition, it can be divided into galvanized steel sheets for general use, roof use, building outer plate, structural use, ridge plate, drawing and deep drawing.

The quality requirements of high-quality galvanized sheet include specification, size, appearance, galvanized quantity, chemical composition, sheet shape, mechanical properties and packaging.
1. Packaging
It can be divided into two types: galvanized sheet cut into fixed length and galvanized sheet with coil. General iron sheet packaging, lined with moisture-proof paper, bound with iron waist outside, and firmly bound to prevent the internal galvanized sheet from rubbing against each other
2. Specification and size
The recommended standard thickness, length, width and allowable deviation of galvanized sheet are listed in the relevant product standards (as follows and). In addition, the width and length of the board and the width of the roll can also be determined according to user requirements.
3. Appearance
Surface state: Due to the different treatment methods in the coating process, the surface state of the galvanized sheet is also different, such as ordinary zinc flake, fine zinc flake, flat zinc flake, non-zinc flake and phosphating surface. The galvanized sheet and galvanized coil cut into fixed length shall not have defects that affect the use (detailed below), but the coil shall be allowed to have several abnormal parts such as welding parts.
4. Galvanizing quantity
Standard value of galvanized quantity: galvanized quantity is a commonly used effective method to indicate the thickness of zinc coating on galvanized sheet. There are two types of zinc plating: the same amount of zinc plating on both sides (i.e. equal thickness zinc plating) and the different amount of zinc plating on both sides (i.e. differential thickness zinc plating). The unit of galvanizing is g/m2.
5. Mechanical properties
(1) Tensile test: generally speaking, only galvanized sheet for structural, tensile and deep drawing has tensile property requirements.
(2) Bending test: It is the main item to measure the technological performance of thin plate. However, the requirements of national standards for various galvanized sheets are not consistent. Generally, after the galvanized sheet is bent for 180o, the zinc layer on the outer surface shall not be separated, and the sheet base shall not be cracked or broken.
6. Chemical composition
The requirements for the chemical composition of galvanized base plate are different in national standards. If Japan does not require it, the United States requires it. Generally, finished product inspection is not conducted.
7. Plate shape
There are two indicators to measure the flatness, namely, flatness and sickle bending. The flatness of the plate and the allowable value of the sickle bend Z have certain provisions.
The main foreign standards related to galvanized sheet are listed below for reference [4, 5]:
JIS G3302 galvanized steel sheet
JIS G3313 Electrogalvanized steel sheet and strip
ASTM A525 General requirements for hot-dip galvanized steel sheets
ASTM A526 commercial grade hot-dip galvanized steel sheet
ASTM 527 Hot-dip galvanized steel sheet of bite forming grade
ASTM 528 deep-drawing grade hot-dip galvanized steel sheet
ASTM A361 Hot Dip Galvanized Steel Sheet for Roof and Wall Panels
ASTM A444 Hot Dip Galvanized Steel Sheet for Trench
ASTM A446 hot-dip galvanized steel sheet of structural grade
ASTM A599 Cold-rolled galvanized steel sheet
ASTM A642 hot-dip galvanized special deoxidized deep-drawing steel sheet
？ OCT 7118 galvanized steel sheet
DIN 17162 Part 1 Low carbon steel hot-dip galvanized steel strip and plate
DIN 17162 part 2 hot-dip galvanized steel sheet
JIS H0401 Test method for hot-dip galvanizing
DIN 50952 Test method for hot-dip galvanizing