A B C DE F G H I J K L M N O P Q R Sa-Sq St-Sy T U V W X Y Z
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earing
The formation of ears or scalloped edges around the top of a drawn shell, resulting from directional differences in the plastic-working properties of rolled metal, with, across, or at angles to the direction of rolling.
eccentric press
A mechanical press in which an eccentric, instead of a crankshaft, is used to move the slide.
ECM
An abbreviation for electrochemical machining.
eddy-current testing
An electromagnetic nondestructive testing method in which eddy-current flow is induced in the test object. Changes in flow caused by variations in the object are reflected into a nearby coil or coils where they are detected and measured by suitable instrumentation.
edge dislocation
See dislocation.
edger (edging impression)
The portion of a die impression that distributes metal during forging into areas where it is most needed in order to facilitate filling the cavities of subsequent impressions to be used in the forging sequence. See also fuller (fullering impression).
edge strain
Transverse strain lines or Lüders lines ranging from 25 to 300 mm (1 to 12 in.) in from the edges of cold rolled steel sheet or strip. See also Lüders lines.
edging
(1) In sheet metal forming, reducing the flange radius by retracting the forming punch a small amount after the stroke but before release of the pressure. (2) In rolling, the working of metal in which the axis of the roll is parallel to the thickness dimension. Also called edge rolling. (3) The forging operation of working a bar between contoured dies while turning it 90° between blows to produce a varying rectangular cross section. (4) In a forging, removing flash that is directed upward between dies, usually accomplished using a lathe.
EDM
Abbreviation for electrical discharge machining.
effective crack size
The physical crack size augmented for the effects of crack tip plastic deformation. Sometimes the effective crack size is calculated from a measured value of a physical crack size plus a calculated value of a plastic zone adjustment. A preferred method for calculation of effective crack size compares compliance from the secant of a load-deflection trace with the elastic compliance from a calibration for the type of specimen.
effective draw
The maximum limits of forming depth that can be achieved with a multiple-action press; sometimes called maximum draw or maximum depth of draw.
885 °F (475 °C) embrittlement
Embrittlement of stainless steels upon extended exposure to temperatures between 400 and 510 °C (750 and 950 °F). This type of embrittlement is caused by fine, chromium-rich precipitates that segregate at grain boundaries; time at temperature directly influences the amount of segregation. Grain-boundary segregation of the chromium-rich precipitates increases strength and hardness, decreases ductility and toughness, and changes corrosion resistance. This type of embrittlement can be reversed by heating above the precipitation range.
ejector
A device mounted in such a way that it removes or assists in removing a formed part from a die.
ejector half
The movable half of a die-casting die containing the ejector pins.
ejector rod
A rod used to push out a formed piece.
elastic constants
The factors of proportionality that relate elastic displacement of a material to applied forces. See also bulk modulus of elasticity , modulus of elasticity , Poisson’s ratio , and shear modulus.
elastic deformation
A change in dimensions directly proportional to and in phase with an increase or decrease in applied force.
elastic hysteresis
A misnomer for an anelastic strain that lags a change in applied stress, thereby creating energy loss during cyclic loading. More properly termed mechanical hysteresis.
elasticity
The property of a material by virtue of which deformation caused by stress disappears upon removal of the stress. A perfectly elastic body completely recovers its original shape and dimensions after release of stress.
elastic limit
The maximum stress that a material is capable of sustaining without any permanent strain (deformation) remaining upon complete release of the stress. A material is said to have passed its elastic limit when the load is sufficient to initiate plastic, or nonrecoverable, deformation. See also proportional limit.
elastic modulus
Same as modulus of elasticity.
elastic ratio
Yield point divided by tensile strength.
elastic strain
See elastic deformation.
elastic strain energy
The energy expended by the action of external forces in deforming a body elastically. Essentially all the work performed during elastic deformation is stored as elastic energy, and this energy is recovered upon release of the applied force.
electrical discharge grinding
Grinding by spark discharges between a negative electrode grinding wheel and a positive workpiece separated by a small gap containing a dielectric fluid such as petroleum oil.
electrical discharge machining (EDM)
Metal removed by a rapid spark discharge between different polarity electrodes, one on the workpiece and the other the tool separated by a gap distance of 0.013 to 0.9 mm (0.0005 to 0.035 in.). The gap is filled with dielectric fluid and metal particles that are melted, in part vaporized, and expelled from the gap.
electrical discharge wire cutting
A special form of electrical discharge machining wherein the electrode is a continuous moving conductive wire. Also referred to as traveling wire electrical discharge machining.
electrical disintegration
Metal removal by an electrical spark acting in air. It is not subject to precise control, the most common application being the removal of broken tools such as taps and drills.
electrical pitting
The formation of surface cavities by removal of metal as a result of an electrical discharge across an interface.
electric arc furnace
See arc furnace.
electric arc spraying
See preferred term arc spraying.
electric furnace
A metal melting or holding furnace that produces heat from electricity. It may operate on the resistance or induction principle. See also induction furnace.
electrochemical cell
An electrochemical system consisting of an anode and a cathode in metallic contact and immersed in an electrolyte. The anode and cathode may be different metals or dissimilar areas on the same metal surface. See also cathodic protection.
electrochemical corrosion
Corrosion that is accompanied by a flow of electrons between cathodic and anodic areas on metallic surfaces.
electrochemical discharge machining
Metal removal by a combination of the processes of electrochemical machining and electrical discharge machining. Most of the metal removal occurs via anodic dissolution (i.e., ECM action). Oxide films which form as a result of electrolytic action through an electrolytic fluid are removed by intermittent spark discharges (i.e., EDM action). Hence, the combination of the two actions.
electrochemical equivalent
The weight of an element or group of elements oxidized or reduced at 100% efficiency by the passage of a unit quantity of electricity. Usually expressed as grams per coulomb.
electrochemical grinding
A process whereby metal is removed by deplating. The workpiece is the anode; the cathode is a conductive aluminum oxide-copper or metal-bonded diamond grinding wheel with abrasive particles. Most of the metal is removed by deplating; 0.05 to 10% is removed by abrasive cutting.
electrochemical machining (ECM)
Controlled metal removal by anodic dissolution. Direct current passes through flowing film of conductive solution which separates the workpiece from the electrode tool. The workpiece is the anode, and the tool is the cathode.
electrochemical potential
The partial derivative of the total electrochemical free energy of a constituent with respect to the number of moles of this constituent where all factors are kept constant. It is analogous to the chemical potential of a constituent except that it includes the electric as well as chemical contributions to the free energy. The potential of an electrode in an electrolyte relative to a reference electrode measured under open circuit conditions.
electrochemical reaction
A reaction caused by passage of an electric current through a medium that contains mobile ions (as in electrolysis); or, a spontaneous reaction made to cause current to flow in a conductor external to this medium (as in a galvanic cell). In either event, electrical connection is made to the external portion of the circuit via a pair of electrodes. See also electrolyte.
electrochemical series
Same as electromotive force series.
electrode
Compressed graphite or carbon cylinder or rod used to conduct electric current in electric arc furnaces, arc lamps, and so forth.
electrode (electrochemistry)
One of a pair of conductors introduced into an electrochemical cell, between which the ions in the intervening medium flow in opposite directions and on whose surfaces reactions occur (when appropriate external connection is made). In direct current operation, one electrode or “pole” is positively charged, the other negatively. See also anode , cathode , electrochemical reaction , and electrolyte.
electrode (welding)
(1) In arc welding, a current-carrying rod that supports the arc between the rod and work, or between two rods as in twin carbon-arc welding. It may or may not furnish filler metal. See also bare electrode , covered electrode , flux cored electrode , lightly coated electrode , metal cored electrode , metal electrode , and stranded electrode. (2) In resistance welding, a part of a resistance welding machine through which current and, in most instances, pressure are applied directly to the work. The electrode may be in the form of a rotating wheel, rotating roll, bar, cylinder, plate, clamp, chuck, or modification thereof. (3) In arc and plasma spraying, the current-carrying components that support the arc.
electrode cable
Same as electrode lead.
electrode deposition
The weight of weld-metal deposit obtained from a unit length of electrode.
electrode extension
For gas metal arc welding, flux cored arc welding, and submerged arc welding, the length of unmelted electrode extending beyond the end of the contact tube.
electrode force
The force between electrodes in a spot, seam, and projection weld.
electrode holder
A device used for mechanically holding the electrode while conducting current to it.
electrode indentation (resistance welding)
The depression formed on the surface of workpieces by electrodes.
electrode lead
The electrical conductor between the source of arc welding current and the electrode holder.
electrode polarization
Change of electrode potential with respect to a reference value. The change may be caused, for example, by the application of an external electrical current or by the addition of an oxidant or reductant.
electrodeposition
(1) The deposition of a conductive material from a plating solution by the application of electrical current. (2) The deposition of a substance on an electrode by passing electric current through an electrolyte. Electroplating, electroforming, electrorefining, and electrotwinning result from electrodeposition.
electrode potential
The potential of an electrode in electrolysis as measured against a reference electrode. The electrode potential does not include any resistance losses in potential in either the solution or external circuit. It represents the reversible work to move a unit charge from the electrode surface through the solution to the reference electrode.
electrode reaction
Interfacial reaction equivalent to a transfer of charge between electronic and ionic conductors. See also anodic reaction and cathodic reaction.
electroforming
Making parts by electrodeposition on a removable form.
electrogalvanizing
The electroplating of zinc upon iron or steel.
electrogas welding (EGW)
An arc welding process that produces coalescence of metals by heating them with an arc between a continuous filler metal electrode and the work. Molding shoes are used to confine the molten weld metal for vertical position welding. The electrodes may either be flux cored or solid. Shielding may or may not be obtained from an externally supplied gas or mixture.
electroless plating
(1) A process in which metal ions in a dilute aqueous solution are plated out on a substrate by means of autocatalytic chemical reduction. (2) The deposition of conductive material from an autocatalytic plating solution without the application of electrical current.
electrolysis
(1) Chemical change resulting from the passage of an electric current through an electrolyte. (2) The separation of chemical components by the passage of current through an electrolyte.
electrolyte
(1) A chemical substance or mixture, usually liquid, containing ions that migrate in an electric field. (2) A chemical compound or mixture of compounds which when molten or in solution will conduct an electric current.
electrolytic brightening
Same as electropolishing.
electrolytic cell
An assembly, consisting of a vessel, electrodes, and an electrolyte, in which electrolysis can be carried out.
electrolytic cleaning
A process of removing soil, scale, or corrosion products from a metal surface by subjecting it as an electrode to an electric current in an electrolytic bath.
electrolytic copper
Copper that has been refined by electrodeposition, including cathodes that are the direct product of the refining operation, refinery shapes cast from melted cathodes, and, by extension, fabricators’ products made therefrom. Usually when this term is used alone, it refers to electrolytic tough pitch copper without elements other than oxygen being present in significant amounts. See also tough pitch copper.
electrolytic deposition
Same as electrodeposition.
electrolytic grinding
A combination of grinding and machining wherein a metal-bonded abrasive wheel, usually diamond, is the cathode in physical contact with the anodic workpiece, the contact being made beneath the surface of a suitable electrolyte. The abrasive particles that produce grinding act as nonconducting spacers permitting simultaneous machining through electrolysis.
electrolytic machining
Controlled removal of metal using an applied potential and a suitable electrolyte to produce the shapes and dimensions desired.
electrolytic picking
Pickling in which electric current is used, the work being one of the electrodes.
electrolytic polishing
An electrochemical polishing process in which the metal to be polished is made the anode in an electrolytic cell where preferential dissolution at high points in the surface topography produces a specularly reflective surface. Also referred to as electropolishing.
electrolytic powder
Powder produced by electrodeposition or by pulverizing of an electrodeposit.
electrolytic protection
See preferred term cathodic protection.
electrolytic tough pitch
A term describing the method of raw copper preparation to ensure a good physical- and electrical-grade copper-finished product.
electromagnetic forming
A process for forming metal by the direct application of an intense, transient magnetic field. The workpiece is formed without mechanical contact by the passage of a pulse of electric current through a forming coil. Also known as magnetic pulse forming.
electromagnetic radiation
Energy propagated at the speed of light by an electromagnetic field. The electromagnetic spectrum includes the following approximate wavelength regions:
Region Wavelength, (nm)
Gamma-ray 0.005 to 1.40 (0.0005 to 0.14)
X-ray 0.1 to 100 (0.01 to 10)
Far-ultraviolet 100 to 2000 (10 to 200)
Near-ultraviolet 2000 to 3800 (200 to 380)
Visible 3800 to 7800 (380 to 780)
Near-infrared 7800 to 30,000 (0.78 to 3 m)
Middle-infrared 3 × 104 to 3 × 105 (3 to 30 m)
Far-infrared 3 × 105 to 3 × 106 (30 to 300 m)
Microwave 3 × 106 to 1 × 1010 (0.3 mm to 1 m)
electromechanical polishing
An attack-polishing method in which the chemical action of the polishing fluid is enhanced or controlled by the application of an electric current between the specimen and the polishing wheel.
electrometallurgy
Industrial recovery or processing of metals and alloys by electric or electrolytic methods.
electromotive force
(1) The force that determines the flow of electricity; a difference of electric potential. (2) Electrical potential; voltage.
electromotive force series (emf series)
A series of elements arranged according to their standard electrode potentials, with “noble” metals such as gold being positive and “active” metals such as zinc being negative. In corrosion studies, the analogous but more practical galvanic series of metals is generally used. The relative positions of a given metal are not necessarily the same in the two series.
electron bands
Energy states for the free electrons in a metal, as described by the use of the band theory (zone theory) of electron structure. Also called Brillouin zones.
electron beam cutting
A cutting process that uses the heat obtained from a concentrated beam composed primarily of high-velocity electrons, which impinge on the workpieces to be cut; it may or may not use an externally supplied gas.
electron beam heat treating
A selective surface hardening process that rapidly heats a surface by direct bombardment with an accelerated stream of electrons.
electron beam machining
Removing material by melting and vaporizing the workpiece at the point of impingement of a focused high-velocity beam of electrons. The machining is done in high vacuum to eliminate scattering of the electrons due to interaction with gas molecules. The most important use of electron beam machining is for hole drilling.
electron beam welding (EBW)
A welding process that produces coalescence of metals with the heat obtained from a concentrated beam composed primarily of high-velocity electrons impinging on the surfaces to be joined.
electrophoresis
Transport of charged colloidal or macromolecular materials in an electric field.
electroplate
The application of a metallic coating on a surface by means of electrolytic action.
electroplating
The electrodeposition of an adherent metallic coating on an object serving as a cathode for the purpose of securing a surface with properties or dimensions different from those of the substrate.
electropolishing
A technique commonly used to prepare metallographic specimens, in which a high polish is produced making the specimen the anode in an electrolytic cell, where preferential dissolution at high points smooths the surface. Also referred to as electrolytic polishing.
electrorefining
Using electric or electrolytic methods to convert impure metal to purer metal, or to produce an alloy from impure or partly purified raw materials.
electroslag remelting (ESR)
A consumable-electrode remelting process in which heat is generated by the passage of electric current through a conductive slag. The droplets of metal are refined by contact with the slag.
electroslag welding (ESW)
A welding process that produces coalescence of metals with molten slag that melts the filler metal and the surfaces of the workpieces. The weld pool is shielded by this slag, which moves along the full cross section of the joint as welding progresses. The process is initiated by an arc that heats the slag. The arc is then extinguished by the conductive slag, which is kept molten by its resistance to electric current passing through the electrode and the workpieces.
electrostrictive effect
The reversible interaction, exhibited by some crystalline materials, between an elastic strain and an electric field. The direction of the strain is independent of the polarity of the field. Compare with piezoelectric effect.
electrotinning
Electroplating tin on an object.
electrotyping
The production of printing plates by electroforming.
electrowinning
Recovery of a metal from an ore by means of electrochemical processes.
elongation
(1) A term used in mechanical testing to describe the amount of extension of a test piece when stressed. (2) 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. See also elongation, percent.
elongation, percent
The extension of a uniform section of a specimen expressed as a percentage of the original gage length: where Lo is the original gage length and Lx is the final gage length.
elutriation
A test for particle size in which the speed of a liquid or gas is used to suspend particles of a desired size, with larger sizes settling for removal and weighing, while smaller sizes are removed, collected, and weighed at certain time intervals.
embossing
(1) Technique used to create depressions of a specific pattern in plastic film and sheeting. Such embossing in the form of surface patterns can be achieved on molded parts by the treatment of the mold surface with photoengraving or another process. (2) Raising a design in relief against a surface.
embossing die
A die used for producing embossed designs.
embrittlement
The severe loss of ductility or toughness or both, of a material, usually a metal or alloy. Many forms of embrittlement can lead to brittle fracture. Many forms can occur during thermal treatment or elevated-temperature service (thermally induced embrittlement). Some of these forms of embrittlement, which affect steels, include blue brittleness, 885 °F (475 °C) embrittlement, quench-age embrittlement, sigma-phase embrittlement, strain-age embrittlement, temper embrittlement, tempered martensite embrittlement, and thermal embrittlement. In addition, steels and other metals and alloys can be embrittled by environmental conditions (environmentally assisted embrittlement). The forms of environmental embrittlement include acid embrittlement, caustic embrittlement, corrosion embrittlement, creep-rupture embrittlement, hydrogen embrittlement, liquid metal embrittlement, neutron embrittlement, solder embrittlement, solid metal embrittlement, and stress-corrosion cracking.
emf
An abbreviation for electromotive force.
emission spectroscopy
The branch of spectroscopy treating the theory, interpretation, and application of spectra originating in the emission of electromagnetic radiation by atoms, ions, radicals, and molecules.
emissivity
Ratio of the amount of energy or of energetic particles radiated from a unit area of a surface to the amount radiated from a unit area of an ideal emitter under the same conditions.
emulsion
A stable dispersion of one liquid in another, generally by means of an emulsifying agent that has affinity for both the continuous and discontinuous phases. The emulsifying agent, discontinuous phase, and continuous phase can together produce another phase that serves as an enveloping (encapsulating) protective phase around the discontinuous phase.
emulsion cleaner
A cleaner consisting of organic solvents dispersed in an aqueous medium with the aid of an emulsifying agent.
enameling iron
A low-carbon, cold-rolled sheet steel, produced specifically for use as a base metal for porcelain enamel.
enantiotropy
The relation of crystal forms of the same substance in which one form is stable above a certain temperature and the other form is stable below that temperature. For example, ferrite and austenite are enantiotropic in ferrous alloys.
end mark
A roll mark caused by the end of a sheet marking the roll during hot or cold rolling.
end milling
A method of machining with a rotating cutting tool with cutting edges on both the face end and the periphery. See also face milling and milling.
endothermic atmosphere
A gas mixture produced by the partial combustion of a hydrocarbon gas with air in an endothermic reaction. Also known as endogas.
endothermic reaction
Designating or pertaining to a reaction that involves the absorption of heat. See also exothermic reaction.
end-quench hardenability test
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 from the quenched end.
endurance limit
The maximum stress that a material can withstand for an infinitely large number of fatigue cycles. See also fatigue limit and fatigue strength.
endurance ratio
The ratio of the endurance limit for completely reversed flexural stress to the tensile strength of a given material.
engineering strain (e)
A term sometimes used for average linear strain or conventional strain in order to differentiate it from true strain. In tension testing it is calculated by dividing the change in the gage length by the original gage length.
engineering stress (s)
A term sometimes used for conventional stress in order to differentiate it from true stress. In tension testing, it is calculated by dividing the breaking load applied to the specimen by the original cross-sectional area of the specimen.
environmental cracking
Brittle fracture of a normally ductile material in which the corrosive effect of the environment is a causative factor. Environmental cracking is a general term that includes corrosion fatigue, high-temperature hydrogen attack, hydrogen blistering, hydrogen embrittlement, liquid metal embrittlement, solid metal embrittlement, stress-corrosion cracking, and sulfide stress cracking. The following terms have been used in the past in connection with environmental cracking, but are becoming obsolete: caustic embrittlement, delayed fracture, season cracking, static fatigue, stepwise cracking, sulfide corrosion cracking, and sulfide stress-corrosion cracking. See also embrittlement.
epitaxy
Growth of an electrodeposit or vapor deposit in which the orientation of the crystals in the deposit are directly related to crystal orientations in the underlying crystalline substrate.
epsilon ()
Designation generally assigned to intermetallic, metal-metalloid, and metal-nonmetallic compounds found in ferrous alloy systems, for example, Fe3Mo2, FeSi, and Fe3P.
epsilon carbide
Carbide with hexagonal close-packed lattice that precipitates during the first stage of tempering of primary martensite. Its composition corresponds to the empirical formula Fe2.4C.
epsilon structure
Structurally analogous close-packed phases or electron compounds that have ratios of seven valence electrons to four atoms.
equiaxed grain structure
A structure in which the grains have approximately the same dimensions in all directions.
equilibrium
The dynamic condition of physical, chemical, mechanical, or atomic balance that appears to be a condition of rest rather than one of change.
equilibrium diagram
A graph of the temperature, pressure, and composition limits of phase fields in an alloy system as they exist under conditions of thermodynamical equilibrium. In metal systems, pressure is usually considered constant. Compare with phase diagram.
Erichsen test
A cupping test used to assess the ductility of sheet metal. The method consists of forcing a conical or hemispherical-ended plunger into the specimen and measuring the depth of the impression at fracture.
erosion
(1) Loss of material from a solid surface due to relative motion in contact with a fluid that contains solid particles. Erosion in which the relative motion of particles is nearly parallel to the solid surface is called abrasive erosion. Erosion in which the relative motion of the solid particles is nearly normal to the solid surface is called impingement erosion or impact erosion. (2) Progressive loss of original material from a solid surface due to mechanical interaction between that surface and a fluid, a multicomponent fluid, and impinging liquid, or solid particles. (3) Loss of material from the surface of an electrical contact due to an electrical discharge (arcing). See also cavitation erosion , electrical pitting , and erosion-corrosion.
erosion-corrosion
A conjoint action involving corrosion and erosion in the presence of a moving corrosive fluid, leading to the accelerated loss of material.
erosivity
The characteristic of a collection of particles, liquid stream, or a slurry that expresses its tendency to cause erosive wear when forced against a solid surface under relative motion.
etchant
A chemical solution used to etch a metal to reveal structural details. See also etching.
etch cleaning
Removing soil by dissolving away some of the underlying metal.
etch cracks
Shallow cracks in hardened steel containing high residual surface stresses, produced by etching in an embrittling acid.
etch figures
Characteristic markings produced on crystal surfaces by chemical attack, usually having facets parallel to low-index crystallographic planes.
etching
(1) Subjecting the surface of a metal to preferential chemical or electrolytic attack in order to reveal structural details for metallographic examination. (2) Chemically or electrochemically removing tenacious films from a metal surface to condition the surface for a subsequent treatment, such as painting or electroplating.
eutectic
(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 a phase diagram. (3) An alloy structure of intermixed solid constituents formed by a eutectic reaction often in the form of regular arrays of lamellas or rods.
eutectic carbide
Carbide formed during freezing as one of the mutually insoluble phases participating in the eutectic reaction of ferrous alloys.
eutectic melting
Melting of localized microscopic areas whose composition corresponds to that of the eutectic in the system.
eutectic point
The composition of a liquid phase in univariant equilibrium with two or more solid phases; the lowest melting alloy of a composition series.
eutectoid
(1) An isothermal reversible reaction in which a solid 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 eutectoid point on a phase diagram. (3) An alloy structure of intermixed solid constituents formed by a eutectoid reaction.
eutectoid point
The composition of a solid phase that undergoes univariant transformation into two or more other solid phases upon cooling.
exfoliation
Corrosion that proceeds laterally from the sites of initiation along planes parallel to the surface, generally at grain boundaries, forming corrosion products that force metal away from the body of the material, giving rise to a layered appearance. Most commonly associated with wrought aluminum alloys.
exogenous inclusion
An inclusion that is derived from external causes. Slag, dross, entrapped mold materials, and refractories are examples of inclusions that would be classified as exogenous. In most cases, these inclusions are macroscopic or visible to the naked eye. Compare with indigenous inclusion.
exothermic
Characterized by the liberation of heat.
exothermic atmosphere
A gas mixture produced by the partial combustion of a hydrocarbon gas with air in an exothermic reaction. Also known as exogas.
exothermic reaction
A reaction that liberates heat, such as the burning of fuel or when certain plastic resins are cured chemically.
expanding
A process used to increase the diameter of a cup, shell, or tube. See also bulging.
expendable pattern
A pattern that is destroyed in making a casting. It is usually made of wax (investment casting) or expanded polystyrene (lost foam casting).
explosion welding
A solid-state welding process that produces coalescence by a controlled detonation, which causes the parts to move together at high velocity. The resulting bond zone has a characteristic wavy appearance.
explosive forming
The shaping of metal parts in which the forming pressure is generated by an explosive charge that takes the place of the punch in conventional forming. See also high-energy-rate forming.
extensometer
An instrument for measuring changes in length over a given gage length caused by application or removal of a force. Commonly used in tension testing.
extractive metallurgy
The branch of process metallurgy dealing with the winning of metals from their ores. Compare with refining.
extra hard
A temper of nonferrous alloys and some ferrous alloys characterized by values of tensile strength and hardness about one-third of the way from those of full hard to those of extra spring temper.
extra spring
A temper of nonferrous alloys and some ferrous alloys corresponding approximately to a cold-worked state above full hard beyond which further cold work will not measurably increase strength or hardness.
extreme-pressure lubricant
A lubricant that imparts increased load-carrying capacity to rubbing surfaces under severe operating conditions. Extreme-pressure lubricants usually contain sulfur, halogens, or phosphorus.
extruded hole
A hole formed by a punch that first cleanly cuts a hole and then is pushed farther through to form a flange with an enlargement of the original hole.
extrusion
The conversion of an ingot or billet into lengths of uniform cross section by forcing metal to flow plastically through a die orifice. In forward (direct) extrusion, the die and ram are at opposite ends of the extrusion stock, and the product and ram travel in the same direction. Also, there is relative motion between the extrusion stock and the die. In backward (indirect) extrusion, the die is at the ram end of the stock and the product travels in the direction opposite that of the ram, either around the ram (as in the impact extrusion of cylinders such as cases for dry cell batteries) or up through the center of a hollow ram. See also hydrostatic extrusion and impact extrusion.
extrusion billet
A metal slug used as extrusion stock.
extrusion defect
See preferred term extrusion pipe.
extrusion forging
(1) Forcing metal into or through a die opening by restricting flow in other directions. (2) A part made by the operation.
extrusion ingot
A cast metal slug used as extrusion stock.
extrusion pipe
A central oxide-lined discontinuity that occasionally occurs in the last 10 to 20% of an extruded metal bar. It is caused by the oxidized outer surface of the billet flowing around the end of the billet and into the center of the bar during the final stages of extrusion. Also called coring.
extrusion stock
A rod, bar, or other section used to make extrusions.
eyeleting
The displacing of material about an opening in sheet or plate so that a lip protruding above the surface is formed.