1. Chemical corrosion: surface environmental pollution: adhering to the surface of the precision casting parts of the oil, dust, acid, alkali, salt, etc. in certain cases are converted into corrosive media, and with some of the components of the stainless steel plate components to produce chemical changes. Surface scraping: all kinds of scraping is going to destroy the passivation treatment film, precision vacuum casting and thus reduce the corrosion resistance of the stainless steel plate, and facilitate the reflection with organic chemical media, and thus cause chemical corrosion and rust.
2. Clean-up: pickling passivation and passivation treatment, if clean-up is not clean, the residual liquid will be residual, stainless steel plate will be immediately leached. For example, in the pickling passivation process, the acidic and alkaline liquid state into the casting shrinkage loose, and subsequently reflect with oxygen, causing yellow spots on the surface of the casting. Laser cutting: rust-prone raw materials, such as laser cutting slag, spatter and adhesion of corrosive media will produce primary cells and cause galvanic corrosion.
3. Carbon steel environmental contamination: scratches and corrosive media due to contact with carbon steel parts can create primary cells and cause galvanic corrosion. For example, in the sand removal process of castings, the application of carbon steel shot has the opportunity for organic chemical adhesion to the surface of the stainless steel plate, which in turn causes rust to occur on the surface of the casting. Large casting peening: fire heating area of the composition and metal components transformed unevenly, and with corrosive media to produce primary cells, resulting in electrochemical corrosion.