Why do aluminum coil stocks have white patches?

Why do aluminum coil stocks have white patches?

aluminum coil stocks surface appears how to return a responsibility? Placed in semi-enclosed warehouse, the surface of [color=rgba(0, 191, 255, 0.8)]aluminum coil stocks will produce white patches (especially in winter) after one week. What’s the matter? How to prevent?[/color]

[img=300x0]http://www.aluminiumstrip-hm.com/wp-content/uploads/2018/07/201703290853012800-300x259.jpg[/img]
1. This is the problem of mildew of aluminum alloy. Quicklime can be placed in the stacking place. Due to the humidity of warehouse air, the oxidization phenomenon can only make the warehouse environment dry and ventilated. In fact, this phenomenon often occurs in aluminum plate manufacturing enterprises
Aluminum alloy in open or semi-closed is very easy to oxidize, mildew, so must be done protection.
4 d & _5 ~ (B B ‘; ` ([in view of the product has oxidation, cleaning can be done to oxidation, and make protective treatment.
2. After the test and analysis, the experts found that the defect of aluminum alloymaterial is the main reason, and the extrusion — heat treatment process is unreasonable. If we want to solve the problem fundamentally, we need to strictly control the chemical composition of aluminum alloy. At the same time, the ingot was treated by homogenizing annealing as much as possible, and the ingot was cooled by rapid cooling.