The surface coating of galvalume steel is composed of 55% aluminum, 43.5% zinc and a small amount of other elements. Under the micro level, the surface of aluminized zinc coating is honeycomb structure, and the "honeycomb" composed of aluminum contains zinc. In this case, although aluminized zinc coating also plays the role of anode protection, However, on the one hand, due to the reduction of zinc content, on the other hand, due to the fact that the zinc material is wrapped by aluminum and is not easy to be electrolyzed, the role of anode protection is greatly reduced. Therefore, once the aluminized zinc plate is cut, it will soon rust when the cut edge is basically lost. Therefore, the aluminized zinc plate should be cut as little as possible. Once cut, the edge should be protected with antirust paint or zinc rich paint, The service life of the plate can be extended.(galvalume steel)