Main metal material of car body shell: galvanized steel plate

The car body shell is mainly composed of metal materials, of which steel plates are mainly used. In order to prevent steel plate rust, modern cars use a variety of methods. First, the steel plate surface of the car shell will be coated with a layer of paint, which can effectively isolate air and moisture, thereby preventing the steel plate from rusting. In addition, car manufacturers will also use plating technology on the steel plate to improve the corrosion resistance of the steel plate by covering it with a metal film. These measures can ensure that the car will not rust during use, thus guaranteeing its service life.

Some cars claim that the body rust protection period is more than 10 years, which is because of the use of better rust prevention materials and more advanced rust prevention processes in the manufacturing process. These cars not only use high-strength steel plates, but also apply a thicker anti-rust paint, and will also use some anti-rust materials inside the body, such as waterproof tape. In addition, these cars are subjected to a series of rigorous quality tests and experiments to ensure that their rust resistance reaches the highest level.

It has been widely used in the automotive industry, and its secret weapon is that it has excellent corrosion resistance. This reminds me of an interesting experiment: in the early days, scientists put iron and zinc in salt water without any wires connecting the two. It was found that both iron and zinc rust, iron produces red rust, zinc produces "white rust". However, when a wire is connected between the two, iron does not rust, while zinc produces "white rust". It's like zinc protecting iron, a curious phenomenon known as "sacrificial anode protection."

This principle has been cleverly applied to actual production, and galvanized steel plates have been produced. After in-depth study, it was found that when the galvanized amount reached 350 grams/square meter (single side), the life of galvanized steel plate in outdoor use (red rust) is about 15 to 18 years in the pastoral zone, and about 3 to 5 years in the industrial zone. This is much longer than ordinary steel plate, even up to ten times.

Since the 1970s, the car body steel plate has begun to use galvanized sheet steel. 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 painted. With the continuous improvement of corrosion resistance requirements of automobiles, galvanized steel plates continue to increase the weight of galvanized layers, and double-layer galvanized steel plates have appeared. However, due to the increase in galvanizing weight, the electrical energy consumption of galvanizing will increase significantly, resulting in an increase in material costs, so in the late 1970s, there was a galvanized steel sheet produced by the hot-dip galvanizing process, called hot-dip galvanized steel sheet.

This galvanized steel plate adopts continuous hot dip galvanizing process: cold rolled sheet → heating → cooling to galvanizing temperature → galvanizing → cooling → straightening. In order to meet the various requirements of automobile galvanized steel plate, some manufacturers carry out special treatment such as diffusion annealing on galvanized steel plate in galvanized production line, so that a "zinc-iron" alloy coating is formed on the surface of the steel plate. It is characterized by better weldability and corrosion resistance after painting than pure zinc coating. Since then, there have also been alloyed hot-dip galvanized steel plates such as "zinc-aluminum-silicon" and "zinc-aluminum-rhenium", which have doubled the corrosion resistance of hot-dip galvanized steel plates and provided long-term stability in combination with paint.

At present, the car has been widely used galvanized steel plate, its thickness from 0.5 to 3.0 mm. Among them, the body cover parts are mostly galvanized steel plates of 0.6 to 0.8 mm. Most of the body parts of German Audi cars are galvanized steel plates (some are aluminum alloy plates); More than 80% of the steel plates used in Buick cars in the United States are double-sided hot-dip galvanized steel plates. The outer cover of the Shanghai Passat body adopts electric galvanizing process, and the inner cover uses hot dip galvanizing process, which makes the body anti-rust shelf life of up to 11 years. These cars use galvanized steel in the body material, which not only improves the durability of the body, but also provides a safer riding environment for passengers.

At present, galvanized steel plates have been widely used in cars, and the thickness of galvanized steel plates used is from 0.5 to 3.0 mm, of which 0.6 to 0.8 mm galvanized steel plates are used in the body cover parts. Most of the body parts of German Audi car are galvanized steel plate (some aluminum alloy plate), more than 80% of the steel plate used by the United States Buick car is double-sided hot galvanized steel plate, Shanghai Passat body of the outer cover of the use of electric galvanizing process, the internal cover of the use of hot galvanizing process, can make the body rust shelf life of up to 11 years.