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flake

Archaeol
a. a fragment removed by chipping or hammering from a larger stone used as a tool or weapon
b. (as modifier): flake tool

Flake

 

in archaeology, the name for chips struck from a piece of flint or flint core by human hands. Flakes varied in shape and size. During the Stone and Bronze ages, tools, including knives, were made from flakes.


Flake

 

an internal crack in forged or rolled steel products, and sometimes ingots and cast articles, that markedly detracts from the desired mechanical properties of the steel. In pickled micro-sections, flakes are identified as hairline cracks; in the fracture testing of hardened specimens, flakes are oval, crystalline spots of a silvery white color distinguishable from the primary gray mass of the fracture. The steels most susceptible to flake damage are alloyed and carbon martensitic and pearlitic steels used for structural members, bearings, armor, and rails. Defects of this type are not found in austenitic or carbide steels (stainless and high-speed steels).

The principal cause of the formation of flakes is the presence of excessive hydrogen, and the mechanism most likely responsible is adsorption of hydrogen on the surfaces of microscopic irregularities, which reduces surface energy and makes destruction easier. Flakes originate in zones with heightened adsorption of hydrogen. The formation of such zones stimulates internal tensile stresses that arise in the steel during structural transformations, plastic deformation, and uneven cooling. Flake development is also promoted by a reduction in the metal’s resistance to destruction in places where stresses have concentrated near accumulations of defects of the crystal lattice, as well as by concentrations of nonmetallic inclusions and segregated inhomogeneities. Flakes may be controlled by thermal treatment of the parts under special conditions and by subjecting the molten steel to a vacuum, which reduces the hydrogen content to a safe level.

REFERENCES

Dubovoi, V. la. Flokeny v stali. Moscow, 1950.
Moroz, L. S., and B. B. Chechulin. Vodorodnaia khrupkost’ metallov. Moscow, 1967.

V. L. SAFONOV and M. L. BERNSHTEIN

flake

[flāk]
(materials)
Dry, unplasticized, cellulosic plastics base.
Plastic chip used as feed in molding operations.
A small, flat wood particle of predetermined dimensions and uniform thickness, with fiber direction essentially in the plane of the flake.
(metallurgy)
Discontinuous, internal cracks formed in steel during cooling due usually to the release of hydrogen. Also known as fisheye; shattercrack; snowflake.
Fish-scale, flat particles in powder metallurgy. Also known as flake powder.
References in periodicals archive ?
The general term jimbila was used to describe a wide variety of points including unifacial percussion flaked points as well as bifacial pressure flaked Kimberley points.
Pressure flaked points and pressure flakes themselves only occurred in the upper and middle layers of the excavation at Wilinyjibari (Table 2).
Pressure flaked points and 'Kimberley points' in the southeast Kimberley
It is important to note that only particular kinds of post-contact archaeological sites demonstrate this pattern of increased point manufacture, and this relates to the different mechanisms which I have suggested are responsible for the post-contact intensification of pressure flaked point manufacture, and the development of the formal aesthetic of Kimberley points.
Although these samples could never be considered statistically similar, it is worth noting the preference in the post-AD1895 museum collections for bifacial, serrated invasively pressure flaked points.
The result of the establishment of a trade market for intricately worked, invasively pressure flaked points with denticulate and serrate margins was the increased formalisation of point design that occurred in the post-contact period.
Archaeological data from the southeast Kimberley cited here would suggest both a proportionately higher number of points in general on post-contact pastoral station sites, along with a greater preference for the manufacture of invasively pressure flaked points with serrate or denticulate margins (ie 'Kimberley points').