The cause of rust
Stainless steel is a very thin and strong, dense, stable chromium-rich oxide film (protective film) formed by its surface. Prevent oxygen atoms from continuing to penetrate and continue to oxidize, while gaining corrosion resistance. Once there is a reason why the film is constantly damaged, the oxygen atoms in the air or liquid are constantly dissociated, forming loose iron oxides and the metal surfaces are constantly rusted.
Stainless steel is a very thin and strong, dense, stable chromium-rich oxide film (protective film) formed by its surface. Prevent oxygen atoms from continuing to penetrate and continue to oxidize, while gaining corrosion resistance. Once there is a reason why the film is constantly damaged, the oxygen atoms in the air or liquid are constantly dissociated, forming loose iron oxides and the metal surfaces are constantly rusted.
Stainless steel rust may occur for several reasons:
Chlorine ions are present in the environment of use
Chlorine ions are widespread, such as salt/sweat/seawater/sea breeze/soil, etc. Stainless steel in the presence of chlorine ions in the environment, corrosion is fast, even more than ordinary low-carbon steel. Therefore, the use of stainless steel environment is required, and need to be often wiped, remove dust, keep clean and dry. (This will give him a “misusing.” There is an example in the United States: a business with an oak container containing a solution containing chlorine ions, the container has been in use for nearly a hundred years, the 1990s planned to replace, because the oak material is not modern enough, the use of stainless steel replacement 16 days after the container due to corrosion leakage.
No solid solubility treatment has been made
Alloy elements are not dissolved into the substrate, resulting in low alloy content of the substrate tissue, poor corrosion resistance.
Innate intercrystalline corrosion
This titanium- and vanadium-free material has a tendency to corrode between crystals. The addition of titanium and vanadium, along with stable treatment, reduces intercrystalline corrosion. In the air or chemical corrosion medium can resist corrosion of a high alloy steel, stainless steel is a beautiful surface and corrosion resistance, do not have to go through color plating and other surface treatment, but to play the inherent surface properties of stainless steel, used in many aspects of steel, commonly referred to as stainless steel. Representing performance are 13 chrome steel, 18-8 chrome nickel steel and other high alloy steel. From the perspective of gold phase analysis, because stainless steel contains chromium and the surface forms a very thin chromium film, this membrane isolation and steel intrusive oxygen plays a corrosion-resistant role. In order to maintain the corrosion resistance inherent in stainless steel, steel must contain more than 12% chromium. For use where welding is required. Lower carbon content minimizes the amount of carbide extracted in the thermal impact zone near the weld, and the extraction of carbide may cause intercrystalline corrosion (welding erosion) in some environments.
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