. After in-depth research, it was found that when the galvanizing amount reaches 350 g/m2 (single side), the outdoor service life of galvanized steel sheets (red rust) is about 15 to 18 years in rural areas, and about 15 years in industrial areas. 3 to 5 years. This is much longer than ordinary steel plates, even up to ten times longer.

Since the 1970s, galvanized thin steel sheets have been used for car body steel panels. During assembly, the galvanized surface is placed on the inside of the car to improve the corrosion resistance of the body, while the non-galvanized surface is placed on the outside of the car and needs to be spray-painted. As automobile requirements for corrosion resistance continue to increase, galvanized steel sheets continue to increase the weight of the galvanized layer, and double-layer galvanized steel sheets also appear. However, since increasing the weight of galvanizing will significantly increase the power consumption of electro-galvanizing, leading to an increase in material costs, in the late 1970s, a galvanized steel sheet produced using the hot-dip galvanizing process appeared, called hot-dip galvanizing. steel plate.

This kind of galvanized steel sheet adopts the continuous hot-dip galvanizing process: cold-rolled sheet → heating → cooling to galvanizing temperature → galvanizing → cooling → straightening. In order to meet various automotive requirements for galvanized steel sheets, some manufacturers perform special treatments such as diffusion annealing on galvanized steel sheets on galvanizing production lines to form a "zinc-iron" alloy coating on the surface of the steel sheets. Its characteristic is that its weldability and corrosion resistance after painting are better than those of pure zinc plated panels. Since then, alloyed hot-dip galvanized steel sheets such as "zinc-aluminum-silicon" and "zinc-aluminum-rhenium" have appeared, which have doubled the corrosion resistance of hot-dip galvanized steel sheets and their long-term bonding performance with paint. Stablize.

have been widely used in cars, with thicknesses ranging from {{0}}.5 to 3.0 mm. Among them, the body covering parts mostly use galvanized steel plates with a thickness of 0.6 to 0.8 mm. Most of the body parts of Audi cars in Germany are made of galvanized steel sheets (some are made of aluminum alloy sheets); while more than 80% of the steel sheets used in Buick cars in the United States are double-sided hot-dip galvanized steel sheets. The outer covering of the Shanghai Passat body adopts electro-galvanizing process, while the inner covering uses hot-dip galvanizing process, which makes the anti-corrosion shelf life of the body as long as 11 years. These cars use galvanized steel sheets as body materials, which not only improves the durability of the body, but also provides passengers with a safer riding environment.