Forms of Corrosion

Corrosion exhibits itself in a number of ways. A brief description of some of these is provided below.

  • General Corrosion is the most common form of corrosion. It exhibits itself in an overall attack of the metal surface with no apparent concentrations. An example is the effect of atmospheric corrosion.
  • Pitting Corrosion results in a localized, concentrated attack and has the appearance of holes or craters.
  • Crevice Corrosion occurs in shielded areas where stagnant corrosive electrolyte accumulates. This type of corrosion occurs under bolt heads, gasket surfaces, and overlapping metal connections.
  • Erosion-Corrosion is a combination of electrochemical and mechanical damage that occurs in environments of high fluid velocities or mechanical movement between two metals.
  • Selective Leaching results in one constituent of an alloy being selectively removed, leaving a porous replica of the original alloy. An example is the dezincification of brass or bronze and the graphitization of cast iron where iron is removed selectively, leaving a replica composed of carbon or graphite.

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