Mechanical properties of seamless steel pipe after pickling and passivation

Hot rolled seamless pipe and cold drawn seamless steel pipe are steel pipe metal products with hollow structure. Because of its structural characteristics, it is widely used in many fields and plays an extremely important role in China's mechanical processing industry and production development.

The pickling process of seamless pipe is a method to clean the metal surface by using acid solution to remove oil, scale, rust and weld spots on the surface of seamless pipe. Passivation, sometimes referred to as "pickling". If the corrosion products generated by the action of the medium have a dense structure, form a thin film (often invisible) and closely cover the surface of the metal, it will change the surface state of the metal and make the electrode potential of the metal jump greatly in the positive direction, resulting in a passive state of corrosion resistance. For example, when Fe → Fe + +, the standard potential is - 0.44v, which jumps to + 0.5 ~ 1V after passivation, showing the performance of corrosion-resistant precious metal. This layer of film is called passivation film, and the passivation of metal may also be a spontaneous process (for example, a layer of insoluble compound, i.e. oxide film, is formed on the surface of metal). In industry, passivation agent (mainly oxidant) is used to passivate metal to form a protective film.

After pickling and passivation, the seamless pipe becomes cleaner and corrosion-resistant. If necessary, it can be painted (anti-corrosion paint).

Therefore, the mechanical properties of seamless steel pipe have not changed after pickling and passivation.