Corrosion occurs on metals, and it is highly dependent on the environment. As per certain standards like ISO 12944-2 -1998 there are different atmospheric conditions that can corrode the metals and metal alloys when they are subjected to different environmental conditions.
Classification of Corrosion
Certain atmospheric conditions corrode the metals as various types of corrosion occur on the materials. Some types of corrosion that usually occurs on the materials include:
The most common type of corrosion which is found on metals is Edge Corrosion. It is one the well-known example of galvanic corrosion. This rust formation occurs mainly at the edges of the galvanized steel where the cross section of the paint coated metals is subjected to different environmental factors. The cross section of the materials is smaller than the steel substrate which means that the materials are not plated with the appropriate amount of coating that can easily prevent corrosion. Therefore, it usually formed on the less coated steels. The materials from the edge corrosion can be protected by coating the material with sufficient amount of zinc plating.
Corrosion of another kind which is usually seen in the irons is Crevice Corrosion. It is a highly severe and localized type of corrosion that usually occurs within the plated area of the materials. This kind of corrosion occurs due to the defects on the surface, dirt deposits, or certain kind of holes that causes stagnant corrosion on the surface of the material. The defects in the form of holes are sometimes wide enough that allows the moisture or any acid to enter and corrode the material badly.
Next form of corrosion is Filiform. It occurred below the protective painted layer and observed as a thin filament that randomly distributed on the surface of the steel substrates and aluminum substrates. This type of corrosion usually reduces down the strength of the material and reduces the functionality and causes an aesthetic defect. The filament of the material originates from the edges and move ahead to form long filaments with an active corrosion tail.
Apart from the mentioned type of corrosions, there are various types of corrosions that occur on the metal substrates. Now we have to think that how this can be treated? Well, to treat the problem of corrosion, it is necessary to test the resistance of the materials to corrosion.
How the factors of corrosion can be detected?
Although there are many preventive methods for corrosion, still it is quite difficult for the metal products manufacturers to ascertain that how much a metal substrate is resistant to corrosion? The effect of corrosion can be tested by observing the sample under certain atmospheric conditions. The best way to perform the corrosion test on metals is Salt Spray Chambers.
It is highly standardized test chamber, which is designed keeping in mind the standard test method ASTM B117. According to this standard, the instrument is capable enough to create high temperature up to 45 degree, salty environment, moist conditions due to which corrosion occurs. To buy high-quality of salt spray chamber in order to detect the effect of various environmental conditions.