Explain the corrosion conditions of 440B stainless steel flat bar

All metal materials react with o2 in the atmosphere to form an oxide film on the surface. Unfortunately, the iron oxide produced on ordinary carbon steel continues to oxidize, causing rust to develop and eventually produce holes. 440B stainless steel flat bar factories can use spray paint or electroplating with oxidation-resistant metal materials (such as zinc, nickel and chromium) to ensure the surface of the carbon steel, but, as we all know, this protection is only a plastic film. If the protective layer is damaged, the steel underneath will gradually rust.

The corrosion resistance of stainless steel turning rods lies in chromium, but since chromium is one of the components of steel, the protection methods vary.

When the amount of chromium added reaches 10.5%, the atmospheric corrosion resistance of steel can be significantly improved. However, when the chromium content is higher, although the corrosion resistance can still be improved, it is not significant. The reason is that when alloying steel with chromium, the type of surface oxide on the 440B stainless steel flat bar is changed into a surface oxide similar to that produced on pure chromium metal. This tightly adherent chromium-rich oxide protects the surface from further oxidation. This kind of oxide layer is very thin, and the natural gloss of the steel surface can be seen through it, making the stainless steel plate have a unique appearance. Moreover, if the surface is damaged, the exposed steel surface will repair itself by reacting with the atmosphere, forming this "passivation film" again to continue to play a protective role. Therefore, all stainless steel plates have a common characteristic, that is, the chromium content is above 10.5%.

Industrial parks are areas where industry causes atmospheric environmental pollution. Environmental pollution may be caused by gases generated by gasoline and diesel, such as sulfur and nitrogen oxides, or other gases released by chemical companies or production plants. Particulate matter suspended in the air, such as dust formed during steel production or accumulation of iron oxide, can also increase corrosion.