What causes intergranular corrosion in aluminum alloys?
Intergranular corrosion results from chromium depletion in the alloy matrix near grain-boundary chromium carbides (and sometimes nitrides) precipitated during welding or some other high-temperature exposure.
What is the cause of the intergranular corrosion occurrence in stainless steel?
Intergranular corrosion is generally considered to be caused by the segregation of impurities at the grain boundaries or by enrichment or depletion of one of the alloying elements in the grain boundary areas.
What shows intergranular corrosion?
Intergranular corrosion (IGC) It is as a result of chromium depletion, mainly due to the precipitation of chromium carbideschromium carbidesCr3C2 is the most durable of the three compositions, and has an orthorhombic crystal structure with a microhardness of 2280 kg/mm2.https://en.wikipedia.org › wiki › Chromium(II)_carbideChromium(II) carbide - Wikipedia in the grain boundaries. Chromium carbides can be precipitated if the stainless steel is sensitized in the temperature range 550–850°C (1020–1560°F), for example during heat treatment or welding.
How does intergranular corrosion work?
Corrosionpedia Explains Intergranular Corrosion (IGC) When an element adequate for the resistance of corrosion is lost, either from the boundary or the zone adjacent to it, it creates a condition where the spot becomes an anode with reference to the rest of the grain.
What type of corrosion is intergranular corrosion?
What Does Intergranular Corrosion (IGC) Mean? This is a corrosion type that attacks the boundaries of the metal crystallites, as opposed to attacking the surface of the metal. Intergranular corrosion can also be referred to as intergranular attack under a condition known as grain boundary depletion.
What happens to aluminum alloy part affected by intergranular corrosion?
Exfoliation corrosion (Davies, 1999; Zhao and Frankel, 2007) of aluminium alloys is the result of intergranular corrosion. It generally occurs where the alloy microstructure has been heavily deformed (i.e. by rolling) and the grain structure has been flattened and extended in the direction of working.
What is meant by pitting corrosion?
Pitting corrosion is a localized form of corrosion by which cavities or "holes" are produced in the material. Most cases of pitting are believed to be caused by local cathodic sites in an otherwise normal surface. Apart from the localized loss of thickness, corrosion pits can also be harmful by acting as stress risers.
What is the difference between pitting and corrosion?
As nouns the difference between corrosion and pitting is that corrosion is the act of corroding or the condition so produced while pitting is the formation of pits on a surface because of corrosion.
What is pitting and crevice corrosion?
Whereas pitting corrosion occurs across the surface of a component, crevice corrosion is associated with a crevice, be that one that forms around a fastener, washer or joint, in a sharp corner or in an area where the flow of a liquid is slowed i.e. a dead spot.
How is intergranular corrosion removed?
Intergranular corrosion is inspected by using the NDT method, such as ultrasonic inspections or radiography inspection. It is removed by replacing the part.
What can be added to steel to prevent intergranular failure?
The formation of chromium carbides in stainless steel can be prevented by adding the elements titanium (Ti) or Niobium (Nb). (Related reading: The Role of Chromium in Intergranular Corrosion.)Apr 1, 2021