The corrosion resistance of the passenger car body is affected by factors such as the environment, materials used, structural design, manufacturing process and maintenance. Among them, the body electrophoretic coating anti-corrosion in the manufacturing process has been widely concerned in domestic OEMs, and the simultaneous process analysis has been carried out, but the utilization rate of China high quality rolled hard roll steel coil materials is still relatively lagging due to cost constraints. It is very necessary to establish a set of effective body galvanized sheet design database for the anti-corrosion process of passenger car body, so as to formulate the specification of the galvanized sheet of the passenger car body to effectively improve the anti-corrosion performance of the product and optimize the anti-corrosion design cost.

A.Corrosion process of galvanized sheet
Generally, the corrosion process of Galvanized Steel Coil made in China is divided into four stages, namely: the corrosion stage of the plating layer; the sacrificial corrosion prevention stage of the substrate after the partial disappearance of the plating layer; the stage of corrosion inhibition of the substrate by the galvanizing corrosion product; the substrate is uncoated The corrosion phase of the time.

B.Galvanized layer corrosion resistance factor
The thickness of the galvanized layer is one of the most important factors determining the corrosion resistance of the steel substrate. According to the Swedish anti-corrosion study, the anti-corrosion performance of the galvanized layer is the most reasonable when it is 7-10 mm thick, and there are also domestic related researches, the thickness of the coating. It has better resistance to under-film corrosion when it is more than 60g/m2. At the same time, the corrosion resistance of China galvalume steel coating steel coil in actual use depends not only on the galvanized steel sheet itself, but also on the processing state and the use environment of the galvanized steel sheet. These three factors can also become corrosion triangles of the galvanized sheet.