All metals react with oxygen in the atmosphere to form an oxide film on the surface. However, the iron oxide formed on ordinary carbon steel continues to oxidize, so that the rust continues to expand, and eventually holes are formed. Carbon steel surfaces can be secured by electroplating with paint or oxidation-resistant metals such as zinc, nickel, and chromium, but, as is known, this protection is only a thin film. If the protective layer is destroyed, the underlying steel begins to corrode.
The corrosion resistance of stainless steel modular belt conveyor depends on chromium, but because chromium is one of the components of steel, the protection methods are not the same.
When the addition amount of chromium reaches more than 11.7%, the atmospheric corrosion resistance of the modular belt of the stainless steel modular belt conveyor increases significantly, but when the chromium content is higher, although the corrosion resistance can still be improved, it is not obvious. The reason is that alloying steel with chromium changes the type of surface oxide to a surface oxide similar to that formed on pure chromium metal. This tightly adhered chromium-rich oxide protects the surface from further oxidation. This oxide layer is extremely thin, through which the natural luster of the steel surface can be seen, giving the stainless steel modular belt a unique surface. Moreover, if the surface layer is damaged, the exposed steel surface will react with the atmosphere to repair itself, re-form this oxide “passivation film”, and continue to play a protective role.
Therefore, the modular belt elements of all stainless steel conveyors have a common characteristic, that is, the chromium content is above 10.5%.