Crevice corrosion refers to the occurrence of spot-like or ulcer-like macroscopic pits at the crevices of metal components, which is a form of localized corrosion that may occur in the gaps in solution stagnant or in the surface of the shield. Such gaps may be formed at the metal to metal or metal and non-metal joints, for example, where rivets, bolts, gaskets, valve seats, loose surface deposits, and marine organisms are in contact with the candle.

Total corrosion: This is a term used to describe the phenomenon of corrosion that occurs across the surface of the alloy in a relatively homogenous manner. When total corrosion occurs, the village material gradually thins due to corrosion, and even material corrosion fails. Stainless steel may exhibit general corrosion in strong acids and alkalis. The problem of failure caused by extensive corrosion is not a cause for concern, since the corrosion can usually be predicted by simple immersion tests or by referring to literature on corrosion.

Uniform corrosion: It refers to the phenomenon that all metal surfaces exposed to corrosive media are corroded. According to different use conditions, different indicators are required for corrosion resistance, which can be generally divided into two categories:

1. Stainless steel refers to steel that is resistant to corrosion in the atmosphere and in weakly corrosive media. Corrosion rates of less than 0.01 mm/year are considered “completely corrosion resistant”; corrosion rates of less than 0.1 mm/year are considered “corrosion resistant”.

2. Corrosion resistant steels are steels that are resistant to corrosion in a variety of aggressive media.

2. Corrosion resistance of various stainless steels

304 is a versatile stainless steel that is widely used to make equipment and components that require good overall performance (corrosion resistance and formability).

301 stainless steel shows a remarkable work hardening phenomenon when it is deformed, and is used in various occasions where higher strength is required.

302 stainless steel is essentially a variant of 304 stainless steel with a higher carbon content, which can be obtained with higher strength by cold rolling.

302B is a kind of stainless steel with high silicon content. It has high resistance to high temperature oxidation.

The 303 and 303Se are free-cutting stainless steels containing * and selenium, respectively, and are used in applications requiring high cutting power and high lightness. 303Se stainless steel is also used to make parts that require hot boring because the stainless steel has good hot workability under these conditions.

304L is a variant of 304 stainless steel with a low carbon content and is used where welding is required. The lower carbon content minimizes the precipitation of carbides in the heat-affected zone near the weld, and the precipitation of carbides may result in intergranular corrosion of the stainless steel in some environments (weld erosion).

304N is a nitrogen-containing stainless steel that is added to improve the strength of the steel.

305 and 384 stainless steels contain high nickel, which has a low work-hardening rate and are suitable for various occasions requiring high cold formability.