Seamless steel pipe has good low temperature performance and excellent machining performance, so it is widely used in chemical, petroleum, power, nuclear engineering, aerospace, marine, medicine, light industry, textile and other departments. Its main purpose is to prevent corrosion and rust. In engineering, pickling and passivation is usually carried out, so that the corrosion resistance potential of seamless steel pipes can be maximized. So what is the passivation principle of seamless steel pipe? What are the advantages of pickling and passivating seamless steel pipes?
The principle of seamless steel pipe passivated:
The mechanism of its passivation can be explained by the film theory, that is, it is believed that the passivation is due to the interaction between the metal and the oxidizing properties, and a very thin, dense, well-covered, and firmly adsorbed on the metal surface is formed on the metal surface. passivation film. This layer of film exists as a phase, usually a metal oxide compound. It plays the role of completely separating the metal from the corrosive medium, preventing the metal from contacting the corrosive medium, so that the metal basically stops dissolving and forms a passive state to prevent corrosion.
The advantages of seamless steel pipes passivated:
1) Compared with the traditional physical sealing method, the passivation treatment has the characteristics of absolutely not increasing the size of the seamless pipe and changing the color, improving the precision and added value of the seamless pipe, and making the operation more convenient;
2) Since the passivation process is carried out in a non-reactive state, the passivation agent can be added and used repeatedly, so the life of the seamless steel pipe is longer and the cost is more economical.
3) Passivation promotes the oxygen molecular structure passivation film formed on the metal surface, the film layer is dense and stable, and it has a self-repairing effect in the air. Therefore, compared with the traditional method of applying anti-rust oil, passivation formed. The passivation film is more stable and more resistant to corrosion.
Seamless steel pipe refers to a steel pipe that is perforated from a whole round steel and has no welds on the surface. Generally, the production process of seamless steel pipe can be divided into two types: cold-drawing and hot-rolling. The production process of cold-rolling is more complicated than that of hot-rolling, and the accuracy of cold-rolled seamless pipe sizes is also higher than that of hot-rolled seamless pipe.