I. Core Anti-corrosion Foundation: "Active Defense" of Alloy Composition

The corrosion resistance of stainless steel wire ropes is essentially the result of the synergistic effect of key alloy elements such as chromium (Cr), nickel (Ni), and molybdenum (Mo) with oxygen and environmental media. Different elements undertake different defense functions and jointly enhance the corrosion resistance.

Chromium (Cr) : The "core builder" of the passivation film. The chromium content in stainless steel is usually no less than 12% (this is one of the core criteria for determining "stainless steel"). When the steel wire rope comes into contact with air, water or oxygen, the chromium on its surface will preferentially undergo a chemical reaction with oxygen, forming an extremely thin (only 2-5nm thick), dense and continuous film of chromium oxide (Cr₂O₃) - this film is called the "passivation film". The key characteristics of the passivation film are: ① Dense structure, which can act as a "barrier" to isolate the steel wire substrate from external corrosive media such as water, salt spray, acids and alkalis, preventing the substrate from further oxidation; ② It has "self-repairing properties". If the film layer is damaged due to minor friction or scratches, the exposed chromium will quickly rereact with the surrounding oxygen to form a new passivation film at the damaged area, continuously maintaining the protective effect.

Nickel (Ni) : Enhancing the stability and corrosion resistance range of passivation film. The main function of adding nickel is: ① To enhance the "toughness" and "stability" of the passivation film, preventing it from cracking at low temperatures, in high humidity or under slight stress; ② Expand the anti-corrosion scenarios, especially in neutral brine (such as salt spray in Marine environments) and weakly acidic media, nickel can inhibit the erosion of the passivation film by chloride ions and reduce the risk of "pitting corrosion" (local small area corrosion). Therefore, nickel-containing stainless steel wire ropes (such as 304 and 316 models) are more suitable for outdoor, humid or coastal environments.

Ii. Key Anti-corrosion Mechanism: "Dynamic Protection" of Surface Passivation Film

The corrosion resistance of stainless steel wire ropes ultimately depends on the integrity and self-healing property of the surface passivation film. This mechanism is the core that distinguishes it from ordinary carbon steel (which is prone to rust)

The "barrier function" of the passivation film: Although the chromium oxide passivation film is thin, it has a tight structure and is insoluble in water and neutral salt solutions. It can effectively prevent the contact between corrosive media (such as H₂O, O₂, Cl⁻, H⁺) and the steel wire substrate, and fundamentally inhibit the oxidation of iron (ordinary carbon steel does not have this film, and iron will directly react with oxygen and water to form loose iron oxide, that is, rust, and rust cannot prevent further corrosion)

The "self-repairing property" of the passivation film: If the passivation film on the surface of the steel wire rope is partially damaged due to minor collisions or friction, the exposed fresh stainless steel substrate (containing chromium) will immediately react with oxygen in the air to quickly regenerate a new chromium oxide film at the damaged area, "repairing" the protective barrier and preventing the spread of corrosion

The "environmental adaptability" of the passivation film: In neutral and weakly alkaline environments, the stability of the passivation film is extremely strong. Even in a weakly acidic environment, the passivation film can still be maintained as long as the chromium content is sufficient. Only in a strongly acidic environment (such as concentrated hydrochloric acid or sulfuric acid) or a strongly alkaline environment will the passivation film be damaged, leading to the corrosion of the substrate