The simplest method: If stainless steel tableware is not smooth and bright enough, it means it has been corroded

Stainless Steel (Stainless Steel) is the abbreviation of stainless acid-resistant steel and is resistant to air, steam, and water. Steel types that are resistant to chemical corrosive media (acid, alkali, salt, etc.) are called acid-resistant steel. Due to the difference in chemical composition between the two, their corrosion resistance is different. Ordinary stainless steel is generally not resistant to corrosion by chemical media, while acid-resistant steel is generally stainless.

Stainless steel corrosion

The metal surface exposed in the corrosive environment undergoes electrochemical or chemical reactions and is corroded evenly. Parts of the passive film on the surface of stainless steel with weak corrosion resistance will form pitting corrosion reactions due to self-excited reactions, resulting in small holes. In addition, chlorine ions will approach, forming a very corrosive solution, accelerating the speed of the corrosion reaction. There is also intergranular corrosion and cracking inside stainless steel, all of which have a destructive effect on the passivation film on the surface of stainless steel. Therefore, the stainless steel surface must be cleaned and maintained regularly to maintain its gorgeous surface and extend its service life. When cleaning the stainless steel surface, care must be taken not to cause surface scratches. Avoid using washing liquids with bleaching ingredients and abrasives, steel wool, grinding tools, etc. In order to remove the washing liquid, rinse the surface with clean water after washing is completed.

Stainless steel is an extremely thin, strong, fine and stable chromium-rich oxide film (protective film) formed on its surface. Prevent oxygen atoms from continuing to penetrate and oxidize, thereby gaining anti-rust ability. Once this film is continuously damaged for some reason, the oxygen atoms in the air or liquid will continue to separate out, forming loose iron oxide, and the metal surface will be constantly corroded.

The main causes of stainless steel corrosion are as follows

Chloride ions exist in the use environment

Chloride ions are widely present, such as salt/sweat/sea water/sea breeze/ Soil and so on. Stainless steel corrodes very quickly in the presence of chloride ions, even more than ordinary low carbon steel. Therefore, there are requirements for the environment in which stainless steel is used, and it needs to be wiped frequently to remove dust and keep it clean and dry.

No solid solution treatment

The alloy elements are not dissolved into the matrix, resulting in a low alloy content in the matrix structure and poor corrosion resistance.

Innate intergranular corrosion

Dust

Floating iron powder or embedded iron

On any surface, free iron will form Rust and cause corrosion of stainless steel