Specific manifestations of stainless steel corrosion

In many industrial applications, stainless steel materials have very good corrosion resistance. According to actual application data, in addition to mechanical failure, stainless steel corrosion is mainly reflected in local corrosion, that is, stress corrosion, pitting corrosion, intergranular corrosion, and crevice corrosion. These corrosions are introduced below.
Stress corrosion refers to a form of failure of stainless steel materials that bear stress due to crack expansion in a corrosive environment. Stress corrosion cracking has a brittle fracture morphology, but this corrosion may also occur in materials with high toughness. The necessary conditions for the occurrence of this kind of corrosion are the presence of tensile stress and the presence of specific corrosive media. The formation and expansion of cracks are generally perpendicular to the direction of tensile stress.
Pitting corrosion is a form of local corrosion that will form point holes on the surface of the stainless steel plate and continue to corrode deeply without affecting the surrounding stainless steel structure.
The grain boundaries are the complex boundaries between grains with different crystallographic orientations. Therefore, they are favorable areas for the segregation of various solute elements or the precipitation of metal compounds (such as carbides and delta phases) in stainless steel. Therefore, in some corrosive media, the grain boundaries may be corroded first. This type of corrosion is also called intergranular corrosion. Most metals and alloys exhibit intergranular corrosion in specific corrosive media.
Crevice corrosion is also a kind of local corrosion, which may occur on the surface of crevice stainless steel where the solution is stagnant. Gaps sometimes form at the junctions of metal and metal or metal and non-metal, such as where they come into contact with rivets, bolts, washers, etc.
General corrosion is a form of corrosion that occurs across the entire stainless steel material surface. When comprehensive corrosion occurs, the stainless steel material will slowly become thinner due to corrosion, which will also lead to the failure of the stainless steel material over time. Stainless steel materials may undergo comprehensive corrosion in strong acids and alkalis. However, this kind of corrosion is not something to worry about in practical applications.