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Gages |
Mfrs. standard numbering systems
indicating decimal thickness' or diameters. |
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Galling |
- The damaging of one or both
metallic surfaces by removal of particles from localized areas
due to seizure during sliding friction.
- Developing a condition on the
rubbing surface of one or both mating parts where excessive
friction between high spots results in localized welding with
substantial spalling and a further roughening of the surface.
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Galvanic Corrosion |
Corrosion associated with the current
of a galvanic cell consisting of two dissimilar conductors in an
electrolyte or two similar conductors in dissimilar electrolytes.
Where the two dissimilar metals are in contact, the resulting action
is referred to as couple action. |
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Gas Welding |
Welding with a gas flame. |
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Gauge |
A term previously used in referring
to the thickness or diameter of a wrought product. Thickness or
diameter is preferred in dimension description. |
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Glaze |
"Pickup, Roll": Small
particles of aluminum and aluminum oxide generated in the roll bite
which subsequently transfer to the rolled product. It may be
distributed uniformly and/or in streaks. |
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Gouge |
A gross scratch. |
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Gouge, Rolled In |
A more localized gross rolled-in
scratch. |
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Grain |
A solid polyhedral (or 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. (1) (Direction of) Refers to grain
fiber following the direction of rolling and parallel to edges of
strip or sheets. (2) To bend across the grain is to bend at right
angles to the direction of rolling. (3) To bend with the grain is to
bend parallel to the direction of rolling. In steel, the ductility
in the direction of rolling is almost twice that at right angles to
the direction of rolling. |
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Grain Boundary |
Bounding surface between crystals.
When alloys yield new phases (as in cooling), grain boundaries are
the preferred location for the appearance of the new phase. Certain
deterioration, such as season cracking and caustic embrittlement,
occur almost exclusively at grain boundaries. |
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Grain Coarsening |
A heat treatment that produces
excessively large austenitic grains. |
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Grain Flow |
Fiber like lines appearing on
polished and etched sections of forgings, caused by orientation of
the constituents of the metal in the direction of working during
forging. |
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Grain Growth |
- An increase in the average size of
the grains in polycrystalline metal or alloy, usually a result
of heating at elevated temperature.
- An increase in metallic crystal
size as annealing temperature is raised; growth occurs by
invasion of crystal areas by other crystals.
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Grain Size |
- For metals, a measure of the areas
or volumes of grains in a polycrystalline material, usually
expressed as an average when the individual sizes are fairly
uniform. Grain sizes are reported in terms of grains per unit
area or volume, average diameter, or as a grain-size number
derived form area measurements.
- 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.
- A measure of the areas or volumes
of grains in a polycrystalline metal or alloy, usually expressed
as as average when the individual sizes are fairly uniform. In
metals containing two or more phases, the grain size refers to
that of the matrix unless otherwise specified. Grain size is
reported in terms of number of grains per unit area or volume,
average diameter, or as a number derived from area measurements.
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Granular Fracture |
- A type of irregular surface
produced when metal fractures, characterized by a rough, grain
like appearance as differentiated from a smooth silky, or
fibrous, type. It can be sub classified into trans-granular and
inter-granular forms.. This type of fracture is frequently
called crystalline fracture, but the implication that the metal
has crystallized is completely misleading.
- A type of irregular surface
produced when metal is broken, that is characterized by a rough,
grain like appearance as differentiated from a smooth silky, or
fibrous, type. It can be sub-classified into trans-granular and
inter-granular forms. This type of fracture is frequently called
crystalline fracture, but the inference that the metal has
crystallized is not justified.
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Granulation |
The formation of grains immediately
upon solidification. |
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Grease Streak |
A narrow discontinuous streak caused
by rolling over an area containing grossly excessive lubricant
drippage. |
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Guide |
Device for holding the metal in the
proper position, during rolling, or slitting. |
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Guide Scratch |
Scratches or marks appearing parallel
to edges of cold rolled strip caused by scale or other particles
which have become imbedded in or have adhered to the rolling mill
guide. Also applies to similar scratches appearing as a result of
slitting. |
