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Knowing the correct
terminology for the Steel Industry is important for many people. If you
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A
ACID EMBRITTLEMENT
A form of hydrogen embrittlement which may be
induced in some metals by acid treatment such as pickling.
AGING
In a metal or alloy, a change in properties that
generally occurs slowly at room temperature and more rapidly at higher
temperatures.
ALLOYING ELEMENTS
An element added to a metal to effect changes in
property, and which remains within the metal.
ANNEALING
Heating to and holding at a suitable temperature
and then cooling at a suitable rate, for such purposes as reducing hardness,
improving, machinability, facilitating cold working, producing a desired
microstructure, or obtaining desired mechanical, physical or other properties.
Annealing is a broad term covering such thermal treatments as full annealing,
normalizing, etc. When applying to ferrous alloys, the term “annealing,”
without qualification, implies full annealing.
B
BANDED STRUCTURE
A segregated structure of nearly parallel bands
aligned in the direction of working.
BARK
The decarbonized layer just beneath the scale
that results from heating steel in an oxidizing atmosphere.
BESSEMER PROCESS
A process for making steel by blowing air
through molten pig iron containing in a refractory lined vessel so as to remove
by oxidation most of the carbon, silicon and manganese.
BILLET
A solid semi-finished round or square product
that has a minimum width or thickness of 1- ½ inches and the cross-sectional
area varies from 2-¼ to 36 square inches.
BLACK ANNEALING
Box annealing or pot annealing ferrous alloy
sheet, strip or wire. See box annealing.
BLAST FURNACE
A vertical shaft type furnace used for reducing
iron ore to pig iron in a continuous operation. The furnace is charged from the
top, the air blast entering the bottom.
BLISTER
A defect produced by gas bubbles.
BLOWHOLE
A hole in a casting or a weld caused by gas
entrapped during solidification.
BLUE ANNEALING
Heating hot rolled ferrous sheet in an open
furnace to a temperature within the transformation range and then cooling in
air, in order to soften the metal. The formation of a bluish oxide on the
surface.
BLUE BRITTLENESS
Brittleness occurring in some steels after being
heated within the range of 300 to 650°
Fahrenheit and more especially if the steel is worked at the elevated
temperature. Killed steels are virtually free of this kind of brittleness.
BOX ANNEALING
Annealing steel by heating in a sealed container
under conditions that minimize oxidation.
BRIGHT ANNEALING
Annealing in a protective medium to prevent
discoloration of the surface.
C
CARBON STEEL
Steel is classed as carbon steel when no minimum
content is specified or required for aluminum, boron, chromium, cobalt,
columbium, molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any
other element added to obtain a desired ally effect; when the specified minimum
for copper does not exceed 0.40%; or when the maximum content specified for
maganese does not exceed 1.65%; silicon .60%; copper .60%.
CARBURIZING
Introducing carbon into a solid ferrous ally by
holding above the critical temperature in contact with a suitable carbonaceous
material, which may be a solid, liquid or gas.
CASE
In a ferrous alloy, the outer portion that has
been made harder than the inner portion, or core, by carburizing and hardening.
CHIPPING
Removing seams and other surface defects in
metals manually with chisel or gouge or by a continuous machine, before further
processing.
CLEAVAGE PLANE
Planes along which crystals fracture more
easily.
COLD SHUT
A place in metal where two portions of the metal
in either a molten or plastic condition have failed to unite into a solid mass.
COLD WORKING
Plastic deformation of a metal at a temperature
low enough to insure strain hardening.
CORE
The center portion of a piece of steel which may
be of different chemical composition than the outside, as in the case of
carburized parts, or which may have different mechanical properties than the
outside due to the failure of penetration of heat treatment effect.
CROP
The defective ends of a rolled or forged product
which are cut off and discarded.
CYANIDING
Introducing carbon and nitrogen into a solid ferrous ally by holding above the
critical temperature in contact with molten cyanide salt of suitable
composition.
D
DECARBURIZATION
The loss of carbon from the surface of a ferrous
alloy as a result of heating in a medium that reacts with the carbon at the
surface.
DRAWING BACK
A misnomer for tempering. See tempering.
E
ELASTIC LIMIT
Strictly speaking the elastic limit of a
material is the producing a measurable change in length after the load is
released. Owing to the difficulty of making a test to determine the true
elastic limit, it is common practice to apply the load at a constant rate of
increase and also measure the increase of length of the specimen at uniform load
increments. The point, at which the increase in length of the specimen ceases
to bear a direct ratio to the increase in load, is called the proportional
limit. For commercial purposes the elastic limit and the proportional limit may
be considered equal, although the elastic limit will usually be slightly higher
than the proportional limit.
ELONGATION
In tensile testing, the increase in the gage
length, measured after fracture of the specimen within the gage length, usually
expressed as a percentage of the original gage length.
ENDURANCE LIMIT
Maximum stress to which material may be
submitted without causing fatigue failure.
EUTECTOID STEEL
A steel consisting of nothing but pearlite
(about .90 carbon)
F
FERROALLOY
An alloy of iron that
contains a sufficient amount of one or more other chemical elements to be useful
as an agent for inducing these elements into a molten metal, usually steel.
FIBER
A fibrous or woody appearing
structure found in fractures of wrought metal, and generally indicating
directional properties.
FINISHING TEMPERATURE
Temperature at which the hot
working is finished.
FRACTURE TEST
Breaking a metal specimen
and examining the fractured surface with the unaided eye or a low-power
microscope to determine such things as composition, grain size, case depth,
soundness or presence of defects.
FULL ANNEALING
Heating to above the
critical temperature range followed by slow cooling through the range.
G
GRAINS
Metal crystals.
GRAIN GROWTH
(coarsening)
An increase in the size of
grains in polycrystalline metal, usually effected during heating at elevated
temperatures.
H
HARDENING
Increasing the hardness by
suitable treatment, usually involving heating and cooling. When applicable, the
following flame hardening, induction hardening, precipitation hardening and
quench hardening.
HEAT TREATMENT
Method of heating and
cooling of finished metals or alloys to produce certain desirable properties and
conditions.
HOT SHORTNESS
Brittleness in metal in the
hot forming range.
HOT WORKING
Deforming metal plastically
at such a temperature and rate that strain hardening does not occur.
HYPEREUTECTOID STEEL
A steel having more than the
eutectoid percentage (about .90) of carbon.
HYPO—EUTECTOID STEEL
A steel having less than the
eutectoid percentage (about .90) of carbon.
MPACT TEST
A test to determine the behavior of materials
when subjected to high rates of loading, usually in bending, tension or torsion.
I
INGOT
A casting suitable for working or remelting.
INGOT IRON
Commercially pure open-hearth iron.
J
K
KILLED STEEL
Steel deoxidized with a strong deoxidizing agent
such as silicon or aluminum in order to reduce the oxygen content to such a
level that no reaction occurs between carbon and oxygen during solidification.
L
LAP
A seamlike surface defect caused by folding over
fins or sharp corners in hot metal and then rolling or forging them into the
surface.
LAP WELD
Weld made on overlapped edges of scarfed or
beveled skelp to form tubing or pipe.
M
MACROSTRUCTURE
The structure of metals as revealed by
examination of the etched surface of a polished specimen at a magnification not
exceeding ten diameters.
MECHANICAL WORKING
Working metal through rolls, presses, hammers,
etc., to change its shape, properties or structure.
MODULUS OF ELASTICITY
A measure of the rigidity of metal. Ratio of
stress, within proportional limit, to corresponding strain. Specifically, the
modulus obtained in tension or compression is Young’s modulus, stretch modulus
or modulus of extensibility; the modulus obtained in torsion; the modulus
covering the ratio of the mean normal stress to the change in volume is the bulk
modulus. The tangent modulus and secant modulus are not restricted within the
proportional limit; the former is the slope of the stress-strain curve at a
specified point; the latter is the slope of a line from the origin to a
specified point on the stress- strain curve. Also called “elastic modulus” and
“coefficient of elasticity.”
N
NETWORK STRUCTURE
A structure in which the crystals of on
constituent are surrounded by envelopes of another constituent which gives a
network appearance to an etched test specimen.
NITRIDING
Adding nitrogen by heating at a temperature
below the critical in contact with some nitrogenous material.
NORMALIZING
Heating to about 100°F.
above the critical temperature and cooling in still air to ordinary temperature.
O
OVERHEATING—Heating
a metal or alloy to such a high temperature that its properties are impaired.
When the original properties cannot be restores by further heat treating, by
mechanical working or by a combination of working and heat treating, the
overheating is know then as burning.
P
PIG IRON—High
carbon iron—made by reduction of iron ore in the blast furnace.
PIPE—The
central cavity formed by contraction in metal, especially in ingots, during
solidification.
PROPORTIONAL LIMIT—The
maximum stress at which strain remains directly proportional to stress.
Q
QUENCHING—Cooling
rapidly from the hardening temperature by subjecting the part to the proper
coolant such as oil, water, molten salt, molten lead, airblast, etc.
R
RED SHORTNESS—Brittleness
in metal in the hot forming range.
REDUCTION OF AREA—The
decreased of cross-sectional area of a tension test-specimen at a point of
rupture, expressed as percentage of original area.
REFINING TEMPERATURE—Temperature
at which the grain size and structure of the steel is refined, usually above the
upper critical.
RIMMED STEEL—A
low-carbon steel containing sufficient iron oxide to give a continuous evolution
of carbon monoxide while the ingot is solidifying, resulting in a case or rim of
metal virtually free of voids. Sheet and strip products made from the ingot
have very good surface quality.
S
SEAM—On
the surface of metal, an unwelded fold or lap, which appears as a crack, usually
resulting from a defect obtained in casting or working.
SELF-HARDENING STEEL
(Air Hardening)—A steel containing sufficient
carbon and other alloying elements to harden fully during cooling in air or
other gaseous mediums from a temperature above its transformation range. The
term should be restricted to steels that are capable of being hardened by
cooling in air in fairly large sections about two inches or more in diameter.
SHORTNESS—Brittleness.
SINKHEAD OR HOT TOP—An
insulated reservoir on top of an ingot mold holding excess molten metal which it
feeds to the ingot proper when shrinkage occurs. Designed to prevent pipe.
SKELP—Steel
or iron plate from which pipe or tubing is made.
SLAB—A
piece of metal, intermediate between ingot and plate, with the width at least
twice the thickness for rolling down into plates.
SLABBING MILL—A
primary mill which produces slabs.
SOAKING—Holding
steel at fixed temperature long enough for a complete, uniform penetration of
the heat.
SONIMS—Composite
word derived for Solid Non-metallic IMpuritieS.
SPALLING—Cracking
and flaking of the metal surface.
SPHEROIDIZING—Prolonged
heating at a temperature near the critical range followed by relatively slow
cooling, causing the carbides to assume approximately a spherical shape.
T
TAPPING—Opening the outlet of a melting furnace to move metal.
TEEMING—Pouring
a molten metal from a ladle into ingot molds, particularly iron or steel.
TEMPERING—Reheating
a quench-hardened or normalized ferrous alloy to a temperature below the
transformation range and then cooling at any desired rate.
TENSILE STRENGTH—The
maximum load per unit of original cross-sectional area obtained before rupture.
U
V
W
WORK HARDNESS—Hardness
resulting from mechanical working.
x
Y
YIELD POINT—The
load per unit of original cross-section area at which a marked increase in the
deformation of the specimen occurs without increase of load. It is usually
calculated from the load determined by the drop of the beam of the testing
machine or by use of dividers.
Z
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