With the sustained and stable development of China’s national economy, the galvanized steel and galvalume steel has been in rapid growth, and in the field of international trading, China steel prices also attract large amount of requirements of them.
The main difference between galvanized steel and galvalume is the plate coating. Surface of galvanized steel evenly distributed the layer of zinc materials, which plays the role of anodic protection for base material, that means corrosion of zinc material give the protection of the base material , and only when all the zinc coating is corroded ,can harm done to the base metal inside. Galvalume coating surface is made from 55% aluminum, 43.5% zinc and a little amount of other elements. Galvalume coating is of a honeycomb structure under microscopic circumstance .The “honeycomb”, which is made of aluminum, contains all the zinc .In this case, the galvalume coating also plays the role of anodic protection, but with the decrease of the zinc amount, and the zinc material covered by aluminum, the anodic protection reduced greatly. So once the galvalume steel sheets are cut, the cutting edge without protection will soon be corroded. So should galvalume sheets be cut less, and zinc-rich paint or anti-rust paint applied to the cutting edge could be able to increase the life of the steel sheets.
The surface of galvalume sheet is more beautiful than galvanized sheet, while the galvalume sheet is much more expensive than galvanized sheet, and the price of small spangle is more expensive than large spangle.
In a rainy and humid city, once corrosion occurs at some point on galvalume sheet, it will spread increasingly on whole board if you do not take measures timely to slowly rust; while galvanized rust not spread if it occurs at a point.
Even a galvalume with greatest quality cannot overcome this shortcoming. Therefore, when we propose customers of the galvanized products, we will explain to customers the difference between them, if they require galvalume products, then we can only try to use corrosion paint immediately once it is cut.