| Admixture |
The interchange of filler
metal and base metal during welding resulting
in weld metal of composition borrowed from
both. Limited admixture is necessary to complete
metallurgical union across the joint. |
|
| Aging |
The recrystallization that
occurs over an extended period of time, resulting
from austenite or other normally elevated-temperature
structure being retained at a temperature
and under conditions where it has not permanent
stability. The result may be a change in properties
or dimension. Under some circumstances, aging
can be advantageous. |
|
| Alloy |
A material having metallic
characteristics and made up of two or more
elements, one of which is metal. |
|
| Annealing |
The process of softening
a metal by heating it, usually above the upper
critical temperature, and then cooling it
at a slow rate. |
|
| Brittleness |
The tendency of a material
to fail suddenly by breaking, without any
permanent deformation of the material before
failure. |
|
| Composition |
The contents of an alloy,
in terms of what elements are present and
in what amount (by percentage of weight). |
|
| Consumable
electrode |
A metal electrode that
establishes the arc and gradually melts away,
being carried across the arc (deposited) to
provide filler metal into the joint. |
|
| Crack propagation |
The development, growth,
or progress of a crack through a solid. |
|
| Crater
Cracks |
Cracks across the weld
bead crater, resulting from hot shrinkage. |
|
| Deposition rate |
The speed with which filler
metal is added to a weld joint, usually stated
in terms of volume of metal deposited per
minute. |
|
| Ductility |
The ability of a material
to become permanently deformed without failure. |
|
| Fill welds |
Welds in which a filler
metal is deposited into the joint from an
electrode or welding rod, fusing with the
base metal on each side. |
|
| Filler metal |
The metal that is deposited
into the joint from an electrode or welding
rod in order to achieve a weld of desired
properties. |
|
| Fusion |
Melting of metal to the
liquid state, permitting two contacting or
neighboring surfaces to partially exchange
their contents with the result that there
is a thorough blending of the compositions
after cooling. |
|
| Grain |
The crystalline body that
may be viewed under a microscope as having
definable limits. |
|
| Inert Gas |
A gas, such as helium or
argon, which does not chemically combine with
other elements. Such a gas serves as an effective
shield of the welding arc and protects the
molten weld metal against contamination from
the atmosphere until it freezes. |
|
| Lower critical
temperature |
The temperature at which
an alloy completes its transformation from
one solid structure to another, as it cools. |
|
| Metallurgy |
The science and technology
of extracting metals form their ores, refining
them, and preparing them for use. |
|
| Micro-cracks |
Cracks or fissures in a
metallic structure which cannot be seen except
with the aid of a microscope. |
|
| Microstructure |
The detailed structure
of a metal or alloy, as revealed by microscopic
examination, showing the various continuous
phases as well as any non-metallic inclusions. |
|
| Non-ferrous |
Lacking iron in sufficient percentage to
have any dominating influence on properties
of the material. |
|
| Ore |
The rock or earth in which we find metals
in their natural forms. |
|
| Parent metal |
The metal to be welded or otherwise worked
upon; also called the base metal. |
|
| Penetration |
1. The depth below the surface of the base
metal to which welding heat is sufficient
for the metal to melt and become liquid or
semi-liquid. Also called the depth of fusion.
|
| |
2. The ability of arc or electrode to reach
into the root of the groove between two members
being welded. |
|
| Physical Metallurgy |
That division of metallurgy applying to
the changes in structure and properties of
metals as a result of shaping, fabricating
and treating. |
|
| Pick-up |
The absorption of base metal by the weld
metal as the result of admixture. Usually
used specifically in reference to the migration
of carbon or other critical alloying elements
from the base metal into the weld metal. Depending
upon the materials involved, this can be an
asset and not a liability. |
|
| Porosity |
The scattered presence of gas pockets or
inclusions in a metallic solid. Process Metallurgy-That
division of metallurgy applying to the extracting,
refining, and primary shaping of metals into
a usable form. |
|
| Properties |
Those features or characteristics of a metal
that make it useful and distinctive from all
others. |
|
| Reverse Polarity |
An arrangement of the leads from a direct
current power source whereby the electrode
is the positive pole and the work piece is
the negative pole of the arc. |
|
| Straight Polarity |
An arrangement of the leads from a direct
current power source whereby the work piece
is the positive pole and the electrode is
the negative pole of the arc. |
|
| Stress |
The load, or amount of a force, applied
to a material, tending to deform or break
it. |
|
| Stringer bead |
A weld bead deposited along a straight line,
without weaving. Term is usually used only
when there are a number of such beads deposited
parallel to each other. |
|
| Stringers |
The tendency of segregated atoms of alloying
elements or their compounds to attach to one
another in thread-like chains. |
|
| Tensile strength |
The resistance of a material to a force
which is acting to pull it apart. |
|
| Ultimate tensile
strength |
The maximum pulling force to which the material
can be subjected without failure. |
|
| Underbead crack |
A crack in the hardened base metal just
under the fusion line. It usually originates
in the coarse-grained zone and is caused by
hydrogen released from the austenite as it
transforms during cooling. If cooling is rapid,
the free hydrogen cannot escape to the surface
and exerts tremendous pressure on the hard
martensite crystals being formed. Underbead
cracks occur parallel to the fusion line. |
|
| Upper critical
temperature |
The temperature at which an alloy begins
to transform from one solid structure to another
as it cools. |
|
| Weld Metal |
A product of fusion, the metal that was
fully melted by the heat of welding. |
|
| Yield Strength |
The stress point at which permanent deformation
results. |
