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Manufacturers’ standard numbering systems indicating decimal thickness or diameters.


The damaging of one or both metallic surfaces by removal of particles from localized areas due to seizure curing sliding friction.


A solid many-sided crystal consisting of groups of atoms bound together in a regular geometric pattern. In mill practice grains are usually studied only as they appear in one plane. In steel, the ductility in the direction of rolling is almost twice that at right angles to the direction of rolling.

Grain Boundary:

Bounding surface between crystals. When alloys yield new phases, grain boundaries are the preferred location for the appearance of the new phase. Certain deteriorations, such as season cracking and caustic embrittlement, usually occur at grain boundaries.

Grain Growth:

An increase in metallic crystal size as annealing temperature is raised; growth occurs by invasion of crystal areas by other crystals.

Grain Size:

Average diameter of grains in the metal under consideration, or alternatively, the number of grains per unit area. Since increase in grain size is paralleled by lower ductility and impact resistance, the question of general grain size is of great significance.


Individual crystals in metals.

Ground Flat Stock:

Annealed and pre-ground tool steel flats in standard sizes ready for tool room use. These are three common grades: water hardening, oil hardening and air hardening quality.