  Intergranular
corrosion refers to preferential (localized) corrosion along grain boundaries. Grains are
"crystals", usually on a microscopic scale, that constitute the (micro)structure
of metals and alloys. This selective dissolution may lead to the dislodgement of grains.
Intergranular corrosion in sensitized stainless steels and exfoliation in aluminum alloys
represent industrially significant examples of this form of damage.
| It is difficult to detect intergranular corrosion in its
early stages, when the overall loss of thickness remains minimal. Coupon exposures and
microscopic examination of surfaces/metallograhic cross sections may be used. Standardized
laboratory coupon tests are available to screen out susceptible alloys for quality control
purposes. |
References/Literature:
"Intergranular Corrosion of Stainless Alloys", ASTM STP 656,
American Society for Testing and Materials, West Conshohocken, PA, 1978.
Links:
Examples of intergranular corrosion and exfoliation presented by Kennedy Space Center at:
http://corrosion.ksc.nasa.gov/html/intercor.htm
|
|
