The corrosion resistance of stainless steel chemical anchor bolts depends on chromium, but because chromium is one of the components of steel, the protection methods are different.
When the addition amount of chromium reaches 10.5%, the atmospheric corrosion resistance of the steel is significantly increased, but when the chromium content is higher, although the corrosion resistance can still be improved, it is not obvious. The reason is that when steel is alloyed with chromium, the type of surface oxide is changed to a surface oxide similar to that formed on pure chromium metal. This tightly adhered chromium-rich oxide protects the surface and prevents further oxidation. This oxide layer is extremely thin, and the natural luster of the steel surface can be seen through it, giving the stainless steel 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 "passivation film" and continue to play a protective role.
All bolts react with oxygen in the atmosphere to form an oxide film on the surface. Unfortunately, the iron oxide formed on ordinary carbon steel bolts continues to oxidize, causing the corrosion to continue to expand and eventually forming holes. You can use paint or oxidation-resistant bolts for electroplating to ensure the bolt surface, but, as people know, this kind of protection is only a thin film. If the protective layer is damaged, the bolts below will begin to corrode.
Therefore, all stainless steel bolts have a common feature, that is, the chromium content is above 10.5%.
