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Elastic Limit
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The maximum stress that can be applied to a metal without producing
permanent deformation. When external forces act upon a material they
tend to form internal stresses within it which cause deformation. If
the stresses are not too great the material will return to its
original shape and dimension when the external stress is removed. |
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Elasticity
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The property which enables a material to return to its original
shape and dimension. |
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Electrical Steels
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Steels which are characterized by their magnetic properties and are
intended for the manufacture of electrical circuits. They are
supplied in the form of cold rolled sheet or strip, generally less
than 2mm thick and up to 1500mm wide. Grain orientated steels have
preferential magnetic properties in the direction of rolling and
non- grain orientated steels have similar magnetic properties both
transversely and in the direction of rolling. |
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Electroslag Refining
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A specialized steel making process in which a rolled or a cast ingot
in the form of an electrode is remelted in a water cooled copper
mould. The melting is activated by resistive heat generated in a
conductive slag. The resulting product has a similar basic chemical
composition to the original ingot, but is characterized by high
purity and low inclusion content. Typical applications include high
integrity components for the aerospace industry. |
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Elevated Temperature Drawing
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A process of drawing steel bars at elevated temperatures (normally
250-300°C) which under optimum conditions produce steels that have
higher tensile and yield strengths than those cold drawn with the
same degree of reduction. The process is little used in the United
Kingdom. |
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Elongation
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A test to measure the ductility of steel. When a material is tested
for tensile strength it elongates a certain amount before fracture
takes place. The two pieces are placed together and the amount of
extension is measured against marks made before starting the test
and is expressed as a percentage of the original gauge length. |
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Embrittlement
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Reduction in ductility or toughness or both due to a chemical or
physical change. |
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End-Quench Hardenability Test
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A laboratory procedure for determining the hardenability of a steel
or other ferrous alloy; widely referred to as the Jominy test.
Hardenability is determined by heating a standard specimen above the
upper critical temperature, placing the hot specimen in a fixture so
that a stream of cold water impinges on one end, and, after cooling
to room temperature is completed, measuring the hardness near the
surface of the specimen at regularly spaced intervals along its
length. The data are normally plotted as hardness versus distance
form the quenched end. |
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Endurance Limit
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The maximum stress below which a material can presumably endure an
infinite number of stress cycles. If the stress is not completely
reversed, the value of the mean stress, the minimum stress or the
stress ratio also should be stated. Compare with fatigue limit. |
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Equiaxed Crystals
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Crystals, each of which has axes approximately equal in length.
These are normally present in the centre of a steel ingot. |
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Equilibrium Diagram
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A graphical representation of the temperature, pressure and
composition limits of phase fields in an alloy system as they exist
under conditions of complete equilibrium. In metal systems, pressure
is usually considered constant. |
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Etching
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Treatment of a prepared metal surface with acid or other chemical
reagent which, by differential attack, reveals the structure. |
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Eutectic
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(1) An isothermal reversible reaction in which a liquid solution is
converted into two or more intimately mixed solids on cooling, the
number of solids formed being the same as the number of components
in the system. (2) An alloy having the composition indicated by the
eutectic point on an equilibrium diagram. (3) An alloy structure of
intermixed solid constituents formed by eutectic reaction. |
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Eutectoid
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A mixture of two or more constituents which forms on cooling from a
solid solution and transforms on heating at a constant minimum
temperature. A eutectoid steel contains approximately 0.83% carbon. |
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Expendable Thermocouples
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Those thermocouples made of fabric or plastic covered wire. The wire
is provided in coils or on spools. Insulation usually consists of
glass braid, asbestos, or ceramic fiber cloth on each conductor plus
glass braid overall. |
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Extrusion
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The production of a section by forcing a billet to flow through a
die. Often used for producing complex sections, the process is used
with both hot and cold metal. Seamless tubes are produced by forcing
a hot billet to flow through a die over a mandrel positioned
centrally in the die. |
