The rust spots of stainless steel ties, we often say that pitting corrosion is also called pit corrosion or pinhole corrosion. The pitting corrosion of stainless steel ties occurs in a specific corrosive medium. It has certain special effects and generally occurs in solutions containing halogen anions and anions. Among them, chloride and bromide are the most corrosive and have a corrosive side, which is one of the common local corrosion of stainless steel.
1. Let us first understand the causes of pitting corrosion of stainless steel cable tie. When the medium contains some active anions (such as c1-), the passive film on the surface of the stainless steel will be destroyed. Due to the matrix at the damage of the passivation film, the metal is exposed to make it in an activated state, and the passivation film is in a passive state, thus forming an active-passive corrosion cell. Since the area of ​​the anode is much smaller than the area of ​​the cathode and the anode current density is larger, the anode metal corrodes into small holes quickly, which becomes the cause of the formation of pitting corrosion of the stainless steel strap.
2. Let’s take a look at the factors that affect the pitting corrosion of stainless steel cable ties? The influence of the medium. In addition to halide anions, oxidizing metal ions (such as Fe”, Cu, Hg) can also promote pitting corrosion; o and other oxidants in the solution are necessary conditions for pitting corrosion and the influence of alloying elements. The addition of molybdenum to the stainless steel can improve the stability of the film and make the surface of the stainless steel produce a very dense and firm passivation. The film and chromium mainly improve the repair ability or regeneration ability of the passive film of the steel.
3. So how do we prevent the pitting corrosion of stainless steel cable ties?
1. Choose austenitic stainless steel with appropriate molybdenum element and higher chromium;
2).Control the concentration of halogen ions in the solution, especially C1 ion, and avoid local concentration of the solution;
3. Add corrosion inhibitor to increase the PH value of the solution; reduce the temperature of the medium, the higher the temperature, the more significant the pitting corrosion.
4. There are other ways to prevent pitting corrosion of stainless steel cable ties, which requires our practitioners to explore, observe, and be good at summarizing.