Understanding Corrosion in Water Pipelines: A Guide for Pipeline Designers



Last updated: June 15, 2018

What Does Flakes Mean?

Flakes are short, discontinuous internal fissures in wrought metals attributed to stresses produced by localized transformation and decreased solubility of hydrogen during cooling after hot working.

Flakes appear as bright silvery areas in a fracture surface; on an etched surface, they appear as short, discontinuous cracks.

Flakes are also known as fish eyes, shatter cracks or snowflakes.


Corrosionpedia Explains Flakes

Flakes are internal fissures seen in large forgings. Hydrogen picked up during melting and casting segregates at internal voids and discontinuities and produces these defects during forging. Fish eyes are bright patches named for their appearance seen on fracture surfaces, generally of weldments. Hydrogen enters the metal during fusion-welding and produces this defect during subsequent stressing. Steel containment vessels exposed to extremely high hydrogen pressures develop small fissures or micro perforations through which fluids may leak.

Flakes are special discontinuities in steel parts that have the form of silver-colored spots on fracture surfaces or thin, hair-like cracks on a ground and etched template. They appear and grow after a considerable incubation period, often during the operation of the part, which makes them a dangerous defect. Depending on the dimensions, number and position in the metal, flakes can decrease the toughness and ductility of steel to zero and markedly reduce the service life of steel parts and structures, causing unexpected and serious failures.

Fish-scale, flat particles in powder metallurgy, is known as flake powder.



Fish Eyes

Shatter Cracks


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