Alloy Steel |
a steel to which one or more alloying elements other
than carbon have been deliberately added (I.e.
chromium, nickel, molybdenum) to achieve a particular
physical property. |
Annealing
|
the process of subjecting steel to high heat, with
subsequent gradual cooling, to soften the steel
thoroughly and render it less brittle.
|
B |
Chemical symbol for Boron |
Be
|
Chemical symbol for Beryllium
|
Bi |
Chemical symbol for Bismuth |
Billet
|
A section of steel used for rolling into bars, rods,
and sections. It can be a product of the ingot route,
or produced by continuous casting.
|
Bloom |
A large square section of steel intermediate in the
rolling process between an ingot and a billet. Blooms
are often produced by the continuous casting process
eliminating the necessity of first producing an ingot. |
C
|
Chemical symbol for Carbon
|
Ca |
Chemical symbol for Calcium |
Calcium
|
In the form of calcium silicide acts as a deoxidizer
and degasifier when added to steel. Both carbon and
alloy steels modified with small amounts of calcium
show improved machinability and longer tool life.
Transverse ductility and toughness are also enhanced.
|
Carbon |
Carbon is an essential element in steel; it is added in
specific amounts to control the hardness and strength
of the material. In general, increased carbon content
reduces ductility but increases tensile strength and
the ability of the steel to harden when cooled rapidly
from elevated temperatures. |
Carbon Steel
|
A steel whose properties are determined primarily by
the amount of carbon present. Apart from iron and
carbon, manganese up to 1.5% may be present as well as
residual amounts of alloying elements such as nickel,
chromium, molybdenum, etc. It is when one or more
alloying elements are added in sufficient amount that
it is classed as an alloy steel.
|
Carburizing |
is adding carbon to the surface of steel by heating the
metal in contact with carbonaceous solid"s, liquids, or
gases. The depth of the penetration of carbon into the
surface is controlled by the time and temperature of
the treatment. After carburizing it is necessary to
harden the components by heating to a suitable
temperature and quenching. |
Case Hardening
|
a process of surface hardening involving a change in
the composition of the outer layer of an iron-base
alloy by inward diffusion from a gas or liquid followed
by appropriate thermal treatment. Typical hardening
processes are carburizing, cyaniding, carbo-nitriding,
and nitriding. Both carbon and alloy steels are
suitable for case-hardening providing their carbon
content is low, usually up to a maximum of 0.2%.
|
Cb |
Chemical symbol for Columbium |
Ce
|
Chemical symbol for Cerium
|
Charpy Test |
A test to measure the impact properties of steel. |
Chromium
|
When used as an alloying element, chromiumn increases
the hardenability of steel an din association with high
carbon gives resistance to wear and abrasion. Chromium
has an important effect on corrosion resistance and is
present in stainless steels in amounts of 12-20%.
|
Co |
Chemical symbol for Cobalt |
Cobalt
|
An alloying element used in tool, magnet and heat
resisting steels. Together with tungsten and
molybdenum, cobalt is used to form the super high speed
steels.
|
Cold Finished |
a generic term used to designate three classes of cold
processed bars: (1) cold drawn bars, (2) turned and
polished shafting, and (3) ground and polished bars. |
Cr
|
Chemical symbol for Chromium
|
Critical Point |
This generally refers to a temperature at which some
chemical or physical change takes place. The
temperatures vary with the carbon content of the steel
and the rate of cooling. |
Cu
|
Chemical symbol for Copper
|
Decarburization |
when steel is subjected to high temperatures, such as
are used in hot rolling, forging, and heat treating,
there is a loss of carbon at the surface which is known
as decarburization. This is the reverse of
carburization. |
Descaling
|
The process of removing the scale from hot rolled bars
before cold finishing. It is normally carried out by
shot blasting or pickling in acid.
|
Die |
When the term die is applied to steel, it often refers
to the drawing dies through which hot rolled bars are
drawn to produce the finish and dimensional accuracy
that is required for cold finished steel. |
Drawing
|
The process of pulling metal wire, rods, or bars
through a die with the effect of altering the size,
finish, and mechanical properties. It is also a term
used for tempering.
|
Ductility |
the property of a metal which allows it to be
permanently deformed, in tension, before final rupture. |
Elasticity
|
The property which enables a material to return to its
original shape and dimension.
|
Elongation |
the amount of permanent extension in the ruptured
tensile-test specimen. It is usually expressed as a
percentage of the original gage length. |
Endurance Limit
|
a limiting stress below which a metal will withstand a
specified large number of applications of stress.
|
Etching |
Treatment of a prepared metal surface with acid or
other chemical reagent which, by differential attack,
reveals the structure. |
F
|
Chemical symbol for Flourine
|
Fatigue Limit |
The maximum value of the applied alternating stress
which a test piece can stand indefinately. |
Fatigue Strength
|
the unit stress that ruptures a bar after an enormous
(around 40 million) number of repetitions of a load
covering a range of values.
|
Fe |
Chemical symbol for Iron |
Ferrite
|
A constituent of carbon steels. It is magnetic and
soft.
|
Freecutting Steels |
Steels which have had additions made to improve
machinability. The most common additives are sulphur
and lead, while other elements used include tellurium,
selenium, and bismuth. |
Ga
|
Chemical symbol for Gallium
|
Ge |
Chemical symbol for Germanium |
Good Machinability
|
the characteristics of a material that result in easy,
fast machining, less downtime, less secondary finishing
operations, improved tool life, and less overall cost
of the machined part.
|
Grain Size |
Grain size is normally quantified by a numbering
system. Coarse 1-5 and Fine 5-8. The number is derived
from the formula N=2^(n-1) where n is the number of
grains per square inch at a magnification of 100
diameters. Grain size has an important effect on
physical properties. It is generally considered that
fine grain steels have a better combination of strength
and toughness, whereas coarse grain steel have better
machinability. |
Grinding
|
A machining process to perform either of two effects:
(1) to shape components that are too hard to be
machined by conventional methods such as hardened tool
steels and case hardened components, or (2) to obtain a
high degree of dimensional accuracy and surface finish.
|
Guage Length |
Used in the mechanical testing of steel, it is the
length marked on the parallel portion of a tensile test
piece from which the elongation is measured. |
H
|
Chemical symbol for Hydrogen
|
Hardenability |
the ability of a steel to achieve a desired hardness
under defined conditions of heating and cooling. |
Hardening
|
the formation of martensite resulting from the heating
and quenching of certain iron-base alloys.
|
Hardness |
The hardness of steel is generally determined by
testing its resistance to deformation. A number of
methods are employed including Brinell, Vickers and
Rockwell. For steel there is an empirical relationship
between hardness and tensile strength and the hardness
number is often used as a guide to the tensile
strength. |
Heat
|
This term often defines the batch or cast produced from
a single melting operation.
|
Heat Treatment |
one or more operations involving the heating and
cooling of a metal or an alloy in the solid" state for
the purpose of obtaining certain desirable conditions
or properties. |
Hydrogen
|
An undesirable impurity if present in steel and can
cause fine hairline cracks especially in alloy steels.
|
I |
Chemical symbol for Iodine |
Impact Strength
|
the energy absorbed by a specimen under a sudden blow
of a certain intensity.
|
In |
Chemical symbol for Indium |
Inclusions
|
Usually non-metallic particles contained in metal. In
steel they may consist of simple or complex oxides,
sulphides, silicates and sometimes nitrides of iron,
maganese, silicon, aluminium and other elements. In
general they are detrimental to mechanical properties
buy much depends on the number, their size, shape and
distribution.
|
Iron |
The term iron refers to the chemical element iron or
pure iron and is the chief constituent of all
commercial iron and steel. |
Jominy Test
|
A method for determining the hardenability of steel.
|
K |
Chemical symbol for Potassium |
Killed Steel
|
Steel that has been completely deoxidized by the
addition of an agent such as silicon or alumimium,
before casting, so that there is practically no
evolution of gas during solid"ification. Killed steels
are characterized by a high degree of chemical
homogeneity and freedom from porosity.
|
La |
Chemical symbol for Lanthanum |
Lap
|
A defect appearing as a seam on a rolled bar. Laps are
rolled over pieces of material that arise when a bar is
given a pass through the rolls after a sharp overfill
or fin has been formed, causing a protrusion to be
rolled into the surface of the product. The presence of
oxides usually prevents the lap welding to the original
bar surface, so that in subsequent cold finishing it is
carried through as a longitudinal crack.
|
Lead |
When added to steel, lead does not go into solution but
exists in a very finely divided state along the grain
boundaries. It greatly assists machinability as it acts
as a lubricant between steel and the tool face. |
Li
|
Chemical symbol for Lithium
|
Machinability |
Simply defined as a measure of the ease with which a
metal can be machined satisfactorily. |
Manganese
|
One of the most important constituents of steel in
which it fulfils a number of functions. It acts as a
mild de-oxidizing agent. It combines with the sulphur
present to form globular inclusions of Manganese
Sulphide which are beneficial to machining. It increase
tensile strength and hardenability of steel.
|
Martensite |
is the structure in quenched steel. |
Mechanical Properties
|
are those characteristics measured under certain
conditions which reveal the reaction of a material to
an applied force.
|
Mg |
Chemical symbol for Magnesium |
Mn
|
Chemical symbol for Manganese
|
Mo |
Chemical symbol for Molybdenum |
Molybdenum
|
Its use as an alloying element in steel increase
hardenability and in low alloy steels reduces the risk
of temper brittleness. It is used in stainless steels
as well as high speed steels.
|
N |
Chemical symbol for Nitrogen |
Na
|
Chemical symbol for Sodium
|
Nb |
Chemical symbol for Niobium |
Ni
|
Chemical symbol for Nickel
|
Nickel |
One of the most widely used alloying elements in steel.
In amounts of 0.50% to 5.00% its use in alloy steels
increases the toughness and tensile strength without
detrimental effect on the ductility. Nickel also
increases the hardenability. |
Niobium
|
Also known as columbium. Niobium is a strong carbide
forming element.
|
Nitrogen |
Nitrogen is a gas that forms approximately 70% by
volume and 77% by weight of the atmosphere. It can
combine with many metals to form nitrides and is thus
applied to the case hardening of steel. |
Normalizing
|
heating steels to approximately 100 degrees Farenheit
above the critical temperature range followed by
cooling to below that range in still air at ordinary
temperature.
|
O |
Chemical symbol for Oxygen |
Occlusion
|
A term applied, in the case of metals, to the
absorption or entrapment of gases.
|
Os |
Chemical symbol for Osmium |
Oxidation
|
A common form of chemical reaction which is the
combining of oxygen with various elements and
compounds. The corrosion of metals is a form of
oxidation.
|
P |
Chemical symbol for Phosphorus |
Pd
|
Chemical symbol for Palladium
|
Pearlite |
is the structure of annealed or soft steel. |
Ph
|
Chemical symbol for Lead
|
Phosphorus |
The presence of this element in steel is usually
regarded as an undesirable impurity due to its
embrittling effect. In most steels it is limited to a
maximum of 0.050%. |
Quenching
|
the process of cooling steel suddenly by immersion,
usually in water or oil.
|
Ra |
Chemical symbol for Radium |
Rb
|
Chemical symbol for Rubidium
|
Re |
Chemical symbol for Rhenium |
Reduction of Area
|
the diminution in section per unit of original area as
applied to a bar that has been subjected to tensile
forces and ruptured.
|
Rh |
Chemical symbol for Rhodium |
Rockwell Hardness
|
A method for determining the hardness of metals by
determining the depth of penetration of a steel ball.
|
Rolling |
The process of shaping metals by passing it between
rolls revolving at the same peripheral speed and in
opposite directions. |
Ru
|
Chemical symbol for Ruthenium
|
S |
Chemical symbol for Sulphur |
Sb
|
Chemical symbol for Antimony
|
Scale |
The oxidized surface of steel produced during hot
working, such as rolling, and by exposure to air or
steam at elevated temperatures. |
Se
|
Chemical symbol for Selenium
|
Seam |
A surface defect formed from blow holes in the ingot,
non metallic inclusions, or stresses arising during the
solid"ification stage. They appear as longitudinal
discontinuities in the bar. |
Selenium
|
An element that closely resembles sulphur in its
properties. The main use in steel is as a freecutting
additive buy due to high cost its use is limited
primarily to stainless steel.
|
Steel |
Generally defined as a metallic product whose principal
element is iron and where the carbon content is not
more than 2%. |
Stress Relieving
|
a thermal process for reducing internal stresses in
metals.
|
Sulphur |
Generally regarded as an impurity in steel as it can
have detrimental effects on strength, ductility, and
weldability as well as producing hot and cold
shortness. Its content in most steels is limited to a
maximum of 0.050%. Sulphur is beneficial to machining
and is added to freecutting steels in amounts up to
0.35% with the manganese content increased to overcome
any detrimental effects. |
Ta
|
Chemical symbol for Tantalum
|
Tantalum |
A rare metal of silver white color having excellent
corrosion resistance and high melting point. It is
widely used for chemical process equipment and
specialized aero-space and nuclear applications. |
Te
|
Chemical symbol for Tellurium
|
Tellurium |
Its primary use in steel is as an additive in
leadbearing freecutting steels to further improve their
machinability. |
Tempering
|
reheating a hardened steel to a specified temperature
followed by any desired rate of cooling for the purpose
of relieving stresses set up by quenching and to
develop toughness and ductility.
|
Tensile Strength |
the maximum load per unit of original cross sectional
area sustained by a material during the tension test. |
Tension Test
|
a test in which a specimen is broken by applying an
increasing load to the two ends. During the test the
elastic properties and the ultimate tensile strength of
the material are determined. After rupture, the broken
specimen may be measured for elongation and reduction
of area.
|
Ti |
Chemical symbol for Titanium |
Tin
|
When present in steel it is an undesirable impurity
which gives rise to temper brittleness. When used as a
coating, it has good resistance to corrosion for many
applications.
|
Titanium |
Small amounts added to steel contribute to its
soundness and give a finer grain size. |
Tool Steel
|
A generic term applied to a wide range of steels, both
carbon and alloy, which are suitable for various types
of cutting tools, press tools, dies, etc.
|
Toughness |
The ability of a material to withstand shock loading.
It is the exact opposite of brittleness which carries
the implication of sudden failure. |
Tungsten
|
When used as an alloying element, it increases the
strength of steel at normal and elevated temperatures.
|
U |
Chemical symbol for Uranium |
Ultrasonic Inspection
|
A means of locating defects in steel. When acoustic
energy in the ultrasonic range is passed through steel,
the sound waves tend to travel in straight lines. If
there is a defect in the path of the beam it will cause
a reflection of some energy depleting the energy
transmitted. The resulting acoustic shadow can allow
for the detection of these defects.
|
V |
Chemical symbol for Vanadium |
Vacuum Degassing
|
A ladle of molten steel is placed within a chamber
which is then evacuated. This reduces the gas content,
particularly hydrogen, as well as reducing non-metallic
inclusions.
|
Vanadium |
Steels with vanadium have a much finer grain structure. |
W
|
Chemical symbol for Tungsten
|
Yield Point |
the stress at which a piece under strain yields
markedly, becoming permanently distorted without
increase of load. |
Zinc
|
A metallic chemical element used as a protective
coating for iron and steel sheet and wire.
|
Zirconium |
Acts as a deoxidizing element in steel and combines
with sulphur. |
Zn
|
Chemical symbol for Zinc
|
Zr |
Chemical symbol for Zirconium |