Nowadays, stainless steel pipes are very popular, and many daily necessities are made of stainless steel. It is precisely because of its corrosion resistance. Here is a brief introduction to the reasons for its corrosion resistance. Let’s take a look.
Nowadays, stainless steel pipes are very popular, and many daily necessities are made of stainless steel. It is precisely because of its corrosion resistance. Here is a brief introduction to the reasons for its corrosion resistance. Let’s take a look.
Most metals and oxygen will react to form an oxide film on the surface, while the iron oxide formed on ordinary carbon steel continues to oxidize, so that the corrosion continues to expand, and finally forms holes. Paint or oxidation-resistant metals (for example, Zinc, nickel and chromium) are electroplated to ensure the surface of carbon steel. However, as people know, this protection is only a thin film. If the protective layer is damaged, the stainless steel pipe will begin to rust. The corrosion resistance of stainless steel pipes 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 the steel is alloyed with chromium. , The type of surface oxide is changed to be similar to the surface oxide 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 penetrates it. You can see the natural luster of the steel surface, so that the stainless steel tube has a unique surface,
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 protect it. Therefore, stainless steel has a common feature, that is, the chromium content is above 10.5%.
