Galvanized steel sheets have a large market in China, and their consumption is also large, and a considerable number of (heavy) amounts of various galvanized steel sheets are imported each year. Commonly used imported galvanized sheets are hot-dip galvanized sheets, electrogalvanized sheets and galvanized lacquered sheets.
According to the production and processing methods, galvanized steel sheets can be divided into hot-dip galvanized steel sheets (commonly known as galvanized iron sheets), electro-galvanized steel sheets, single-sided or double-sided galvanized steel sheets, alloy composite galvanized steel sheets, etc. There are also colored galvanized steel sheets (commonly known as color plates), printed galvanized steel sheets, and polyvinyl chloride laminated galvanized steel sheets.
According to the use, it can be divided into galvanized steel sheets for general use, roofing, building exterior panels, structural use, tile ridge panels, tensile and deep drawing. The quality requirements for quality grade galvanized sheets include dimensions, appearance, galvanizing, chemical composition, plate shape, mechanical properties and packaging.
It is divided into galvanized sheet cut into fixed length and packaged in galvanized sheet. Generally, the metal packaging is lined with moisture-proof paper, and is tied with iron waist and tied tightly to prevent the inner galvanized sheet from rubbing against each other.
2. Specifications and sizes:
The relevant product standards (below and below) specify the standard thickness, length and width recommended for galvanized sheets and their tolerances. 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 status:
Due to the different treatment methods in the coating process, the galvanized sheet has different surface states, such as ordinary zinc flower, fine zinc flower, flat zinc flower, zinc-free flower and phosphating surface.
4. Standard value of galvanizing amount of galvanizing:
The amount of galvanizing is a commonly used and effective method for indicating the thickness of the zinc layer of the galvanized sheet. There are two types of galvanizing on the two sides (ie equal thickness galvanizing) and two different galvanizing amounts (ie, thick galvanizing). The unit of galvanizing is g/m2.
5. Mechanical properties:
(1) Tensile test: Generally speaking, only galvanized sheets for structural, tensile and deep drawing have tensile properties.
(2) Bending test: It is the main item to measure the performance of the sheet. However, the requirements of various national standards for various galvanized sheets are not consistent. Generally, after the galvanized sheet is bent 180o, the outer surface shall not have a zinc layer to be detached, and the plate base shall not be cracked or broken.
6. Chemical composition:
The requirements for the chemical composition of galvanized substrates vary according to national standards. If Japan does not require it, the United States requires it. Generally no finished product inspection.
7. Shape measurement:
There are two indicators of the shape of the plate, namely the straightness and the sickle bend. The flatness of the board and the maximum allowable value of the file are specified.