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 to maximize the corrosion resistance potential of seamless steel pipes. So what is the passivation principle of seamless steel pipe? What are the advantages of pickling and passivating seamless steel pipes?
The principle of passivation of seamless steel pipe:
The mechanism of its passivation can be explained by thin film theory, that is, passivation is considered to be due to the effect of metal and oxidative properties,When acting, a very thin, dense, passivation film with good coverage and firmly adsorbed on the metal surface is formed on the metal surface. This layer of film exists as a phase, usually a compound of an oxide metal. 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 passivation of seamless steel pipes:
1) Compared with the traditional physical sealing method, the passivation treatment has the characteristics of absolutely not increasing the thickness of the workpiece and changing the color, improving the precision and added value of the seamless steel 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, the performance is stable, and it has a self-healing effect in the air at the same time,Therefore, compared with the traditional method of applying anti-rust oil, the passivation film formed by passivation 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 dimensional accuracy of cold drawn seamless tubing is also higher than that of hot-rolled seamless pipe.