What is the corrosion resistance of stainless steel pipes?

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Nowadays, stainless steel pipes are very popular. Many daily necessities are made of stainless steel. It is because of its corrosion resistance. The following is a brief introduction to the reasons for its corrosion resistance. Let’s take a look.

Most metals react with oxygen to form an oxide film on the surface, while the iron oxide formed on ordinary carbon steel continues to oxidize, expanding the rust and eventually forming holes, which can be exploited with paint or oxidation-resistant metals (e.g., Zinc, Nickel and Chromium) are electroplated to secure the carbon steel surface, but, as it is known, this protection is only a thin film, and if the protective layer is destroyed, the stainless steel tube 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 method of protection varies.

When the addition amount of chromium reaches 10.5%, the atmospheric corrosion resistance of the steel 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 when the steel is alloyed 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 pipe 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 play a protective role. Therefore, all stainless steels have a common characteristic, that is, the chromium content is above 10.5%.