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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cake
(1) A copper or copper alloy casting, rectangular in cross section, used for rolling into sheet or strip. (2) A coalesced mass of unpressed metal powder.
calcination
Heating ores, concentrates, precipitates, or residues to decompose carbonates, hydrates, or other compounds.
calomel electrode
(1) An electrode widely used as a reference electrode of known potential in electrometric measurement of acidity and alkalinity, corrosion studies, voltammetry, and measurement of the potentials of other electrodes. (2) A secondary reference electrode of the composition: Pt/Hg-Hg2Cl2/KCl solution. For 1.0 N KCl solution, its potential versus a hydrogen electrode at 25 °C (77 °F) and one atmosphere is +0.281 V.
calorizing
Imparting resistance to oxidation to an iron or steel surface by heating in aluminum powder at 800 to 1000 °C (1470 to 1830 °F).
camber
(1) Deviation from edge straightness, usually referring to the greatest deviation of side edge from a straight line. (2) The tendency of material being sheared from sheet to bend away from the sheet in the same plane. (3) Sometimes used to denote crown in rolls where the center diameter has been increased to compensate for deflection caused by the rolling pressure. (4) The planar deflection of a flat cable or flexible laminate from a straight line of specified length. A flat cable or flexible laminate with camber is similar to the curve of an unbanked race track.
cam press
A mechanical forming press in which one or more of the slides are operated by cams; usually a double-action press in which the blankholder slide is operated by cams through which the dwell is obtained.
can
A sheathing of soft metal that encloses a sintered metal billet for the purpose of hot working (hot isostatic pressing, hot extrusion) without undue oxidation.
canning
(1) A dished distortion in a flat or nearly flat sheet metal surface, sometimes referred to as oil canning. (2) Enclosing a highly reactive metal within a relatively inert material for the purpose of hot working without undue oxidation of the active metal.
capillary action
(1) The phenomenon of intrusion of a liquid into interconnected small voids, pores, and channels in a solid, resulting from surface tension. (2) The force by which liquid, in contact with a solid, is distributed between closely fitted faying surfaces of the joint to be brazed or soldered.
capillary attraction
(1) The combined force of adhesion and cohesion that causes liquids, including molten metals, to flow between very closely spaced and solid surfaces, even against gravity. (2) In powder metallurgy, the driving force for the infiltration of the pores of a sintered compact by a liquid.
capped steel
A type of steel similar to rimmed steel, usually cast in a bottle-top ingot mold, in which the application of a mechanical or a chemical cap renders the rimming action incomplete by causing the top metal to solidify. The surface condition of capped steel is much like that of rimmed steel, but certain other characteristics are intermediate between those of rimmed steel and those of semikilled steel.
capping
Partial or complete separation of a powder metallurgy compact into two or more portions by cracks that originate near the edges of the punch faces and that proceed diagonally into the compact.
carbide
A compound of carbon with one or more metallic elements.
carbide tools
Cutting or forming tools, usually made from tungsten, titanium, tantalum, or niobium carbides, or a combination of them, in a matrix of cobalt, nickel, or other metals. Carbide tools are characterized by high hardnesses and compressive strengths and may be coated to improve wear resistance. See also cemented carbide.
carbon arc cutting
An arc cutting process in which metals are severed by melting them with the heat of an arc between a carbon electrode and the base metal.
carbon arc welding
An arc welding process that produces coalescence of metals by heating them with an arc between a carbon electrode and the work. No shielding is used. Pressure and filler metal may or may not be used.
carbon edges
Carbonaceous deposits in a wavy pattern along the edges of a steel sheet or strip; also known as snaky edges.
carbon electrode
A nonfiller material electrode used in arc welding or cutting, consisting of a carbon or graphite rod, which may be coated with copper or other coatings.
carbon equivalent
(1) For cast iron, an empirical relationship of the total carbon, silicon, and phosphorus contents expressed by the formula: CE = %C + 0.3(%Si) + 0.33(%P) -0.027(%Mn) + 0.4(%S) (2) For rating of weldability:
carbonitriding
A case-hardening process in which a suitable ferrous material is heated above the lower transformation temperature in a gaseous atmosphere of such composition as to cause simultaneous absorption of carbon and nitrogen by the surface and, by diffusion, create a concentration gradient. The heat-treating process is completed by cooling at a rate that produces the desired properties in the workpiece.
carbonization
The high-temperature conversion of an organic substance into elemental carbon. Should not be confused with carburization.
carbonizing flame
See preferred term reducing flame.
carbon potential
A measure of the ability of an environment containing active carbon to alter or maintain, under prescribed conditions, the carbon level of a steel. In any particular environment, the carbon level attained will depend on such factors as temperature, time, and steel composition.
carbon steel
Steel having no specified minimum quantity for any alloying element–other than the commonly accepted amounts of manganese (1.65%), silicon (0.60%), and copper (0.60%)–and containing only an incidental amount of any element other than carbon, silicon, manganese, copper, sulfur, and phosphorus. Low-carbon steels contain up to 0.30% C, medium-carbon steels contain from 0.30 to 0.60% C, and high-carbon steels contain from 0.60 to 1.00% C.
carbonyl powder
Metal powders prepared by the thermal decomposition of a metal carbonyl compound such as nickel tetracarbonyl Ni(CO)4 or iron pentacarbonyl Fe(CO)5. See also thermal decomposition.
carburizing
Absorption and diffusion of carbon into solid ferrous alloys by heating, to a temperature usually above Ac3, in contact with a suitable carbonaceous material. A form of case hardening that produces a carbon gradient extending inward from the surface, enabling the surface layer to be hardened either by quenching directly from the carburizing temperature or by cooling to room temperature, then reaustenitizing and quenching.
carburizing flame
A gas flame that will introduce carbon into some heated metals, as during a gas welding operation. A carburizing flame is a reducing flame, but a reducing flame is not necessarily a carburizing flame.
case
In heat treating, that portion of a ferrous alloy, extending inward from the surface, whose composition has been altered during case hardening. Typically considered to be the portion of an alloy (a) whose composition has been measurably altered from the original composition, (b) that appears light when etched, or (c) that has a higher hardness value than the core. Contrast with core.
case crushing
A term used to denote longitudinal gouges arising from fracture in case-hardened gears.
case hardening
A generic term covering several processes applicable to steel that change the chemical composition of the surface layer by absorption of carbon, nitrogen, or a mixture of the two and, by diffusion, create a concentration gradient. The processes commonly used are carburizing and quench hardening; cyaniding; nitriding; and carbonitriding. The use of the applicable specific process name is preferred.
CASS test
Abbreviation for copper-accelerated salt-spray test.
castable
In casting, a combination of refractory grain and suitable bonding agent that, after the addition of a proper liquid, is generally poured into place to form a refractory shape or structure that becomes rigid because of chemical action.
castability
(1) A complex combination of liquid-metal properties and solidification characteristics that promotes accurate and sound final castings. (2) The relative ease with which a molten metal flows through a mold or casting die.
casting
(1) Metal object cast to the required shape by pouring or injecting liquid metal into a mold, as distinct from one shaped by a mechanical process. (2) Pouring molten metal into a mold to produce an object of desired shape.
casting defect
Any imperfection in a casting that does not satisfy one or more of the required design or quality specifications. This term is often used in a limited sense for those flaws formed by improper casting solidification.
casting shrinkage
The amount of dimensional change per unit length of the casting as it solidifies in the mold or die and cools to room temperature after removal from the mold or die. There are three distinct types of casting shrinkage. Liquid shrinkage refers to the reduction in volume of liquid metal as it cools to the liquidus. Solidification shrinkage is the reduction in volume of metal from the beginning to the end of solidification. Solid shrinkage involves the reduction in volume of metal from the solidus to room temperature.
casting strains
Strains in a casting caused by casting stresses that develop as the casting cools.
casting stresses
Residual stresses set up when the shape of a casting impedes contraction of the solidified casting during cooling.
cast iron
A generic term for a large family of cast ferrous alloys in which the carbon content exceeds the solubility of carbon in austenite at the eutectic temperature. Most cast irons contain at least 2% carbon, plus silicon and sulfur, and may or may not contain other alloying elements. See also compacted graphite iron , ductile iron , gray iron , malleable iron , and white iron.
cast steel
Steel in the form of a casting.
cast structure
The metallographic structure of a casting evidenced by shape and orientation of grains and by segregation of impurities.
catalyst
A substance capable of changing the rate of a reaction without itself undergoing any net change.
catastrophic failure
Sudden failure of a component or assembly that frequently results in extensive secondary damage to adjacent components or assemblies.
cathode
The negative electrode of an electrolytic cell at which reduction is the principal reaction. (Electrons flow toward the cathode in the external circuit.) Typical cathodic processes are cations taking up electrons and being discharged, oxygen being reduced, and the reduction of an element or group of elements from a higher to a lower valence state. Contrast with anode.
cathode copper
Copper deposited at the cathode in electrolytic refining.
cathode efficiency
Current efficiency at the cathode.
cathode film
The portion of solution in immediate contact with the cathode during electrolysis.
cathodic cleaning
Electrolytic cleaning in which the work is the cathode.
cathodic corrosion
Corrosion resulting from a cathodic condition of a structure usually caused by the reaction of an amphoteric metal with the alkaline products of electrolysis.
cathodic pickling
Electrolytic pickling in which the work is the cathode.
cathodic polarization
The change of the electrode potential in the active (negative) direction due to current flow. See also polarization .
cathodic protection
(1) Reduction of corrosion rate by shifting the corrosion potential of the electrode toward a less oxidizing potential by applying an external electromotive force. (2) Partial or complete protection of a metal from corrosion by making it a cathode, using either a galvanic or an impressed current. Contrast with anodic protection.
cathodic reaction
Electrode reaction equivalent to a transfer of negative charge from the electronic to the ionic conductor. A cathodic reaction is a reduction process. An example common in corrosion is M(aq)2+ + 2e- M(s).
catholyte
The electrolyte adjacent to the cathode of an electrolytic cell.
cation
A positively charged ion that migrates through the electrolyte toward the cathode under the influence of a potential gradient. See also anion and ion.
caustic
(1) Burning or corrosive. (2) A hydroxide of a light metal, such as sodium hydroxide or potassium hydroxide.
caustic cracking
A form of stress-corrosion cracking most frequently encountered in carbon steels or iron-chromium-nickel alloys that are exposed to concentrated hydroxide solutions at temperatures of 200 to 250 °C (400 to 480 °F). Also known as caustic embrittlement.
caustic dip
A strongly alkaline solution into which metal is immersed for etching, for neutralizing acid, or for removing organic materials such as greases or paints.
caustic embrittlement
An obsolete historical term denoting a form of stress-corrosion cracking most frequently encountered in carbon steels or iron-chromium-nickel alloys that are exposed to concentrated hydroxide solutions at temperatures of 200 to 250 °C (400 to 480 °F).
caustic quenching
Quenching with aqueous solutions of 5 to 10% sodium hydroxide (NaOH).
cavitation
The formation and collapse, within a liquid, of cavities or bubbles that contain vapor or gas or both. In general, cavitation originates from a decrease in the static pressure in the liquid. It is distinguished in this way from boiling, which originates from an increase in the liquid temperature. There are certain situations where it may be difficult to make a clear distinction between cavitation and boiling, and the more general definition that is given here is therefore to be preferred. In order to erode a solid surface by cavitation, it is necessary for the cavitation bubbles to collapse on or close to that surface.
cavitation corrosion
A process involving conjoint corrosion and cavitation.
cavitation damage
The degradation of a solid body resulting from its exposure to cavitation. This may include loss of material, surface deformation, or changes in properties or appearance.
cavitation erosion
Progressive loss of original material from a solid surface due to continuing exposure to cavitation.
cavity
The mold or die impression that gives a casting its external shape.
CCT diagram
See continuous cooling transformation diagram.
cell (electrochemistry)
Electrochemical system consisting of an anode and a cathode immersed in an electrolyte. The anode and cathode may be separate metals or dissimilar areas on the same metal. The cell includes the external circuit, which permits the flow of electrons from the anode toward the cathode. See also electrochemical cell.
cementation
The introduction of one or more elements into the outer portion of a metal object by means of diffusion at high temperature.
cement copper
Impure copper recovered by chemical deposition when iron (most often shredded steel scrap) is brought into prolonged contact with a dilute copper sulfate solution.
cemented carbide
A solid and coherent mass made by pressing and sintering a mixture of powders of one or more metallic carbides, such as tungsten carbide, and a much smaller amount of a metal, such as cobalt, to serve as a binder.
cementite
A hard (800 HV), brittle compound of iron and carbon, known chemically as iron carbide and having the approximate chemical formula Fe3C. It is characterized by an orthorhombic crystal structure. When it occurs as a phase in steel, the chemical composition will be altered by the presence of manganese and other carbide-forming elements. The highest cementite contents are observed in white cast irons, which are used in applications where high wear resistance is required.
center drilling
Drilling a short, conical hole in the end of a workpiece–a hole to be used to center the workpiece for turning on a lathe.
centerless grinding
Grinding the outside or inside diameter of a cylindrical piece that is supported on a work support blade instead of being held between centers and that is rotated by a so-called regulating or feed wheel.
centrifugal casting
The process of filling molds by (1) pouring metal into a sand or permanent mold that is revolving about either its horizontal or its vertical axis or (2) pouring metal into a mold that is subsequently revolved before solidification of the metal is complete. See also centrifuge casting.
centrifuge casting
A casting technique in which mold cavities are spaced symmetrically about a vertical axial common downgate. The entire assembly is rotated about that axis during pouring and solidification.
ceramic tools
Cutting tools made from sintered, hot-pressed, or hot isostatically pressed alumina-base or silicon nitride-base ceramic materials.
cermet
A powder metallurgy product consisting of ceramic particles bonded with a metal.
C-frame press
Same as gap-frame press.
CG iron
Same as compacted graphite cast iron.
chamfer
(1) A beveled surface to eliminate an otherwise sharp corner. (2) A relieved angular cutting edge at a tooth corner.
chamfer angle
(1) The angle between a reference surface and the bevel. (2) On a milling contour, the angle between a beveled surface and the axis of the cutter.
chamfering
Making a sloping surface on the edge of a member. Also called beveling.
chaplet
Metal support that holds a core in place within a casting mold; molten metal solidifies around a chaplet and fuses it into the finished casting.
charge
(1) The materials fed into a furnace. (2) Weights of various liquid and solid materials put into a furnace during one feeding cycle.
charging
(1) For a lap, impregnating the surface with fine abrasive. (2) Placing materials into a furnace.
Charpy test
An impact test in which a V-notched, keyhole-notched, or U-notched specimen, supported at both ends, is struck behind the notch by a striker mounted at the lower end of a bar that can swing as a pendulum. The energy that is absorbed in fracture is calculated from the height to which the striker would have risen had there been no specimen and the height to which it actually rises after fracture of the specimen. Contrast with Izod test.
chase (machining)
To make a series of cuts each, except for the first, following in the path of the cut preceding it, as in chasing a thread.
chatter
In machining or grinding, (1) a vibration of the tool, wheel, or workpiece producing a wavy surface on the work and (2) the finish produced by such vibration. (3) In tribology, elastic vibrations resulting from frictional or other instability.
chatter marks
Surface imperfections on the work being ground, usually caused by vibrations transferred from the wheel-work interface during grinding.
check
The intermediate section of a flask that is used between the cope and the drag when molding a shape that requires more than one parting plane.
checked edges
Sawtooth edges seen after hot rolling and/or cold rolling.
checkers
In a chamber associated with a metallurgical furnace, bricks stacked openly so that heat may be absorbed from the combustion products and later transferred to incoming air when the direction of flow is reversed.
checks
(1) Numerous, very fine cracks in a coating or at the surface of a metal part. Checks may appear during processing or during service and are most often associated with thermal treatment or thermal cycling. Also called check marks, or heat checks . (2) Minute cracks in the surface of a casting caused by unequal expansion or contraction during cooling. (3) Cracks in a die impression corner, generally due to forging strains or pressure, localized at some relatively sharp corner. Die blocks too hard for the depth of the die impression have a tendency to check or develop cracks in impression corners. (4) A series of small cracks resulting from thermal fatigue of hot forging dies.
chelating agent
(1) An organic compound in which atoms form more than one coordinate bond with metals in solution. (2) A substance used in metal finishing to control or eliminate certain metallic ions present in undesirable quantities.
chemical conversion coating
A protective or decorative nonmetallic coating produced in situ by chemical reaction of a metal with a chosen environment. It is often used to prepare the surface prior to the application of an organic coating.
chemical deposition
The precipitation or plating-out of a metal from solutions of its salts through the introduction of another metal or reagent to the solution.
chemical flux cutting
An oxygen-cutting process in which metals are severed using a chemical flux to facilitate cutting.
chemically precipitated powder
A metal powder that is produced as a fine precipitate by chemical displacement.
chemical machining
Removing metal stock by controlled selective chemical dissolution.
chemical metallurgy
See process metallurgy.
chemical milling
The machining process in which metal is formed into intricate shapes by masking certain portions and then etching away the unwanted material.
chemical polishing
A process that produces a polished surface by the action of a chemical etching solution. The etching solution is compounded so that peaks in the topography of the surface are dissolved preferentially.
chemical vapor deposition (CVD)
A coating process, similar to gas carburizing and carbonitriding, whereby a reactant atmosphere gas is fed into a processing chamber where it decomposes at the surface of the workpiece, liberating one material for either absorption by, or accumulation on, the workpiece. A second material is liberated in gas form and is removed from the processing chamber, along with excess atmosphere gas.
chemical wear
See corrosive wear.
chevron pattern
A fractographic pattern of radial marks (shear ledges) that look like nested letters “V”; sometimes called a herringbone pattern. Chevron patterns are typically found on brittle fracture surfaces in parts whose widths are considerably greater than their thicknesses. The points of the chevrons can be traced back to the fracture origin.
chill
(1) A metal or graphite insert embedded in the surface of a casting sand mold or core or placed in a mold cavity to increase the cooling rate at that point. (2) White iron occurring on a gray or ductile iron casting, such as the chill in the wedge test. See also chilled iron . Compare with inverse chill.
chilled iron
Cast iron that is poured into a metal mold or against a mold insert so as to cause the rapid solidification that often tends to produce a white iron structure in the casting.
Chinese-script eutectic
A configuration of eutectic constituents, found particularly in some cast alloys of aluminum containing iron and silicon and in magnesium alloys containing silicon, that resembles the characters in Chinese script.
chip breaker
(1) Notch or groove in the face of a tool parallel to the cutting edge, designed to break the continuity of the chip. (2) A step formed by an adjustable component clamped to the face of the cutting tool.
chipping
(1) Removing seams and other surface imperfections in metals manually with a chisel or gouge, or by a continuous machine, before further processing. (2) Similarly, removing excessive metal.
chips
Pieces of material removed from a workpiece by cutting tools or by an abrasive medium.
chlorination
(1) Roasting ore in contact with chlorine or a chloride salt to produce chlorides. (2) Removing dissolved gases and entrapped oxides by passing chlorine gas through molten metal such as aluminum and magnesium.
chromadizing
Improving paint adhesion on aluminum or aluminum alloys, mainly aircraft skins, by treatment with a solution of chromic acid. Also called chromidizing or chromatizing. Not to be confused with chromating or chromizing.
chromate treatment
A treatment of metal in a solution of a hexavalent chromium compound to produce a conversion coating consisting of trivalent and hexavalent chromium compounds.
chromating
Performing a chromate treatment.
chromizing
A surface treatment at elevated temperature, generally carried out in pack, vapor, or salt baths, in which an alloy is formed by the inward diffusion of chromium into the base metal.
chuck
A device for holding work or tools on a machine so that the part can be held or rotated during machining or grinding.
CIP
The acronym for cold isostatic pressing.
circle grid
A regular pattern of circles, often 2.5 mm (0.1 in.) in diameter, marked on a sheet metal blank.
circle-grid analysis
The analysis of deformed circles to determine the severity with which a sheet metal blank has been deformed.
circle grinding
Either cylindrical grinding or internal grinding ; the preferred terms.
circle shear
A shearing machine with two rotary disk cutters mounted on parallel shafts driven in unison and equipped with an attachment for cutting circles where the desired piece of material is inside the circle. It cannot be employed to cut circles where the desired material is outside the circle.
circular field
The magnetic field that (a) surrounds a nonmagnetic conductor of electricity, (b) is completely contained within a magnetic conductor of electricity, or (c) both exists within and surrounds a magnetic conductor. Generally applied to the magnetic field within any magnetic conductor resulting from a current being passed through the part or through a section of the part. Compare with bipolar field.
clad brazing sheet
A metal sheet on which one or both sides are clad with brazing filler metal.
cladding
(1) A layer of material, usually metallic, that is mechanically or metallurgically bonded to a substrate. Cladding may be bonded to the substrate by any of several processes, such as roll-cladding and explosive forming. (2) A relatively thick layer (1 mm, or 0.04 in.) of material applied by surfacing for the purpose of improved corrosion resistance or other properties. See also coating , surfacing , and hardfacing.
clad metal
A composite metal containing two or more layers that have been bonded together. The bonding may have been accomplished by co-rolling, co-extrusion, welding, diffusion bonding, casting, heavy chemical deposition, or heavy electroplating.
clamshell marks
Same as beach marks .
classification
(1) The separation of ores into fractions according to size and specific gravity, generally in accordance with Stokes’ law of sedimentation. (2) Separation of a metal powder into fractions according to particle size.
clearance
(1) The gap or space between two mating parts. (2) Space provided between the relief of a cutting tool and the surface that has been cut.
cleavage
(1) Fracture of a crystal by crack propagation across a crystallographic plane of low index. (2) The tendency to cleave or split along definite crystallographic planes.
cleavage fracture
A fracture, usually of a polycrystalline metal, in which most of the grains have failed by cleavage, resulting in bright reflecting facets. It is one type of crystalline fracture and is associated with low-energy brittle fracture. Contrast with shear fracture.
cleavage plane
A characteristic crystallographic plane or set of planes in a crystal on which cleavage fracture occurs easily.
climb cutting
Analogous to climb milling .
climb milling
Milling in which the cutter moves in the direction of feed at the point of contact.
close annealing
Same as box annealing.
closed-die forging
The shaping of hot metal completely within the walls or cavities of two dies that come together to enclose the workpiece on all sides. The impression for the forging can be entirely either die or divided between the top and bottom dies. Impression-die forging, often used interchangeably with the term closed-die forging, refers to a closed-die operation in which the dies contain a provision for controlling the flow of excess material, or flash , that is generated. By contrast, in flashless forging, the material is deformed in a cavity that allows little or no escape of excess material.
closed dies
Forging or forming impression dies designed to restrict the flow of metal to the cavity within the die set, as opposed to open dies, in which there is little or no restriction to lateral flow.
closed pass
A pass of metal through rolls where the bottom roll has a groove deeper than the bar being rolled and the top roll has a collar fitting into the groove, thus producing the desired shape free from flash or fin.
close-tolerance forging
A forging held to unusually close dimensional tolerances so that little or no machining is required after forging. See also precision forging.
cluster mill
A rolling mill in which each of the two working rolls of small diameter is supported by two or more larger diameter backup rolls.
coalescence
(1) The union of particles of a dispersed phase into larger units, usually effected at temperatures below the fusion point. (2) The growing together or growth into one body of the materials being welded. (3) Growth of grains at the expense of the remainder by absorption or the growth of a phase or particle at the expense of the remainder by absorption or reprecipitation.
coarsening
An increase in grain size, usually, but not necessarily, by grain growth.
coated abrasive
An abrasive product (sandpaper, for example) in which a layer of abrasive particles is firmly attached to a paper, cloth, or fiber backing by means of glue or synthetic-resin adhesive.
coated electrode
See preferred terms covered electrode and lightly coated electrode.
coating
A relatively thin layer (<1 mm, or 0.04 in.) of material applied by surfacing for the purpose of corrosion prevention, resistance to high-temperature scaling, wear resistance, lubrication, or other purposes.
coaxing
Improvement of the fatigue strength of a specimen by the application of a gradually increasing stress amplitude, usually starting below the fatigue limit.
coefficient of friction
The dimensionless ratio of the friction force (F) between two bodies to the normal force (N) pressing these bodies together: ( or f) = (F/N).
coercive force
The magnetizing force that must be applied in the direction opposite to that of the previous magnetizing force in order to reduce magnetic flux density to zero; thus, a measure of the magnetic retentivity of magnetic materials.
cogging
The reducing operation in working an ingot into a billet with a forging hammer or a forging press.
cogging mill
A blooming mill.
coherent precipitate
A crystalline precipitate that forms from solid solution with an orientation that maintains continuity between the crystal lattice of the precipitate and the lattice of the matrix, usually accompanied by some strain in both lattices. Because the lattices fit at the interface between precipitate and matrix, there is no discernible phase boundary.
cohesion
(1) The state in which the particles of a single substance are held together by primary or secondary valence forces. As used in the adhesive field, the state in which the particles of the adhesive (or adherend) are held together. (2) Force of attraction between the molecules (or atoms) within a single phase. Contrast with adhesion.
cohesive strength
(1) The hypothetical stress causing tensile fracture without plastic deformation. (2) The stress corresponding to the forces between atoms.
coil
(1) An assembly consisting of one or more magnet wire windings. (2) Rolled metal sheet or strip.
coil breaks
Creases or ridges in sheet or strip that appear as parallel lines across the direction of rolling and that generally extend the full width of the sheet or strip.
coining
(1) A closed-die squeezing operation, usually performed cold, in which all surfaces of the work are confined or restrained, resulting in a well-defined imprint of the die upon the work. (2) A restriking operation used to sharpen or change an existing radius or profile. (3) The final pressing of a sintered powder metallurgy compact to obtain a definite surface configuration (not to be confused with sizing).
coin silver
An alloy containing 90% silver, with copper being the usual alloying element.
coke
A porous, gray, infusible product resulting from the dry distillation of bituminous coal, petroleum, or coal tar pitch that drives off most of the volatile matter. Used as a fuel in cupola melting.
cold box process
In foundry practice, a two-part organic resin binder system mixed in conventional mixers and blown into shell or solid core shapes at room temperature. A vapor mixed with air is blown into the core, permitting instant setting and immediate pouring of metal around it.
cold chamber machine
A die casting machine with an injection system that is charged with liquid metal from a separate furnace. Compare with hot chamber machine.
cold compacting
See preferred term cold pressing.
cold cracking
(1) Cracks in cold or nearly cold cast metal due to excessive internal stress caused by contraction. Often brought about when the mold is too hard or the casting is of unsuitable design. (2) A type of weld cracking that usually occurs below 205 °C (400 °F). Cracking may occur during or after cooling to room temperature, sometimes with a considerable time delay. Three factors combine to produce cold cracks; stress (for example, from thermal expansion and contraction), hydrogen (from hydrogen-containing welding consumables), and a susceptible microstructure (plate martensite is most susceptible to cracking, ferritic and bainitic structures are least susceptible). See also hot cracking , lamellar tearing , and stress-relief cracking.
cold die quenching
A quench utilizing cold, flat, or shaped dies to extract heat from a part. Cold die quenching is slow, expensive, and is limited to smaller parts with large surface areas.
cold heading
Working metal at room temperature such that the cross-sectional area of a portion or all of the stock is increased. See also heading and upsetting.
cold inspection
A visual (usually final) inspection of forgings for visible imperfections, dimensions, weight, and surface condition at room temperature. The term may also be used to describe certain nondestructive tests such as magnetic-particle, dye-penetrant, and sonic inspection.
cold isostatic pressing (CIP)
Forming technique in which high fluid pressure is applied to a powder (metal or ceramic) part at ambient temperature. Water or oil is used as the pressure medium.
cold lap
(1) Wrinkled markings on the surface of an ingot or casting from incipient freezing of the surface and too low a casting temperature. (2) A flaw that results when a workpiece fails to fill the die cavity during the first forging. A seam is formed as subsequent dies force metal over this gap to leave a seam on the workpiece surface. See also cold shut.
cold mill
A mill for cold rolling of sheet or strip.
cold pressing
Forming a powder metallurgy compact at a temperature low enough to avoid sintering, usually room temperature. Contrast with hot pressing.
cold-rolled sheets
A metal mill product produced from a hot-rolled pickled coil that has been given substantial cold reduction at room temperature. The resulting product usually requires further processing to make it suitable for most common applications. The usual end product is characterized by improved surface, greater uniformity in thickness, and improved mechanical properties compared with hot-rolled sheet.
cold-setting process
In foundry practice, any of several systems for bonding mold or core aggregates by means of organic binders, relying on the use of catalysts rather than heat for polymerization (setting).
cold shortness
Brittleness that exists in some metals at temperatures below the recrystallization temperature.
cold shot
(1) A portion of the surface of an ingot or casting showing premature solidification; caused by splashing of molten metal onto a cold mold wall during pouring. (2) Small globule of metal embedded in, but not entirely fused with, the casting.
cold shut
(1) A discontinuity that appears on the surface of cast metal as a result of two streams of liquid meeting and failing to unite. (2) A lap on the surface of a forging or billet that was closed without fusion during deformation. (3) Freezing of the top surface of an ingot before the mold is full.
Coldstream process
In powder metallurgy, a method of producing cleavage fractures in hard particles through particle impingements in a high-velocity cold gas stream. Also referred to as impact crushing.
cold treatment
Exposing steel to suitable subzero temperatures (-85 °C, or -120 °F) for the purpose of obtaining desired conditions or properties such as dimensional or microstructural stability. When the treatment involves the transformation of retained austenite, it is usually followed by tempering.
cold trimming
The removal of flash or excess metal from a forging at room temperature in a trimming press.
cold welding
A solid-state welding process in which pressure is used at room temperature to produce coalescence of metals with substantial deformation at the weld. Compare with hot pressure welding , diffusion welding , and forge welding.
cold work
Permanent strain in a metal accompanied by strain hardening.
cold-worked structure
A microstructure resulting from plastic deformation of a metal or alloy below its recrystallization temperature.
cold working
Deforming metal plastically under conditions of temperature and strain rate that induce strain hardening. Usually, but not necessarily, conducted at room temperature. Contrast with hot working.
collapsibility
The tendency of a sand mixture to break down under the pressures and temperatures developed during casting.
collet
A split sleeve used to hold work or tools during machining or grinding.
color buffing
Producing a final high luster by buffing. Sometimes called coloring.
coloring
Producing desired colors on metal by a chemical or electrochemical reaction. See also color buffing.
columnar structure
A coarse structure of parallel elongated grains formed by unidirectional growth, most often observed in castings, but sometimes seen in structures resulting from diffusional growth accompanied by a solid-state transformation.
combination die
(1) A die-casting die having two or more different cavities for different castings. (2) For forming, see compound die.
combination mill
An arrangement of a continuous mill for roughing and a guide mill or looping mill for shaping.
combined carbon
Carbon in iron or steel that is combined chemically with other elements; not in the free state as graphite or temper carbon. The difference between the total carbon and the graphite carbon analyses. Contrast with free carbon.
combined cyanide
The cyanide of a metal-cyanide complex ion.
combined stresses
Any state of stress that cannot be represented by a single component of stress; that is, one that is more complicated than simple tension, compression, or shear.
combustion analysis
An analytical technique for determining the concentration of carbon and sulfur in samples. The sample is burned in a graphite crucible in the presence of oxygen, which causes carbon and sulfur to leave the sample as carbon dioxide and sulfur dioxide. These gases are then detected by infrared or thermal conductive means.
comet tails
A group of comparatively deep unidirectional scratches that form adjacent to a microstructural discontinuity during mechanical polishing. They have the general shape of a comet tail. Comet tails form only when a unidirectional motion is maintained between the surface being polished and the polishing cloth.
comminution
(1) Breaking up or grinding an ore into small fragments. (2) Reducing metal to powder by mechanical means. (3) The act or process of reduction of powder particle size, usually but not necessarily by grinding or milling. See also pulverization.
compact
(1) The object produced by the compression of metal powder, generally while confined in a die. (2) The operation or process of producing a compact; sometimes called pressing.
compacted graphite iron
Cast iron having a graphite shape intermediate between the flake form typical of gray cast iron and the spherical form of fully spherulitic ductile cast iron. An acceptable compacted graphite iron structure is one that contains no flake graphite, <20% spheroidal graphite, and 80% compacted graphite (ASTM A 247, type IV). Also known as CG iron or vermicular iron, compacted graphite cast iron is produced in a manner similar to that for ductile cast iron, but using a technique that inhibits the formation of fully spherulitic graphite nodules.
compacting pressure
In powder metallurgy, the specific compacting force related to the area of contact with the press punch expressed in megapascals, meganewtons per square meter, or tons per square inch.
compaction
(1) The act of forcing particulate or granular material together (consolidation) under pressure or impact to yield a relatively dense mass or formed object. (2) In powder metallurgy, the preparation of a compact or object produced by the compression of a powder, generally while confined in a die, with or without the inclusion of lubricants, binders, and so forth. With or without the concurrent applications of heat.
compatibility
A measure of the extent to which materials are mutually soluble in the solid state.
complete fusion
Fusion that has occurred over the entire base material surfaces intended for welding and between all layers and weld beads.
complexing agent
A substance that is an electron donor and that will combine with a metal ion to form a soluble complex ion.
complexion
An ion that may be formed by the addition reaction of two or more other ions.
component
(1) One of the elements or compounds used to define a chemical (or alloy) system, including all phases, in terms of the fewest substances possible. (2) One of the individual parts of a vector as referred to a system of coordinates. (3) An individual functional element in a physically independent body that cannot be further reduced or divided without destroying its stated function, for example, a resistor, capacitor, diode, or transistor.
composite coating
A coating on a metal or nonmetal that consists of two or more components, one of which is often particulate in form. Example: a cermet composite coating on a cemented carbide cutting tool. Also known as multilayer coating.
composite electrode
A welding electrode made from two or more distinct components, at least one of which is filler metal. A composite electrode may exist in any of various physical forms, such as stranded wires, filled tubes, or covered wire.
composite joint
A joint in which welding is used in conjunction with mechanical joining.
composite material
A combination of two or more materials (reinforcing elements, fillers, and composite matrix binder), differing in form or composition on a macroscale. The constituents retain their identities, that is, they do not dissolve or merge completely into one another although they act in concert. Normally, the components can be physically identified and exhibit an interface between one another. Examples are cermets and metal-matrix composites.
composite plate
An electrodeposit consisting of layers of at least two different compositions.
composite powder
A powder in which each particle consists of two or more different materials.
composite structure
A structural member (such as a panel, plate, pipe, or other shape) that is built up by bonding together two or more distinct components, each of which may be made of a metal, alloy, nonmetal, or composite material. Examples of composite structures include: honeycomb panels, clad plate, electrical contacts, sleeve bearings, carbide-tipped drills or lathe tools, and weldments constructed of two or more different alloys.
compound compact
A powder metallurgy compact consisting of mixed metals, the particles of which are joined by pressing or sintering, or both, with each metal particle retaining substantially its original composition.
compound die
Any die designed to perform more than one operation on a part with one stroke of the press, such as blanking and piercing, in which all functions are performed simultaneously within the confines of the blank size being worked.
compressibility
(1) The ability of a powder to be formed into a compact having well-defined contours and structural stability at a given temperature and pressure; a measure of the plasticity of powder particles. (2) A density ratio determined under definite testing conditions. Also referred to as compactibility.
compression ratio (powder metallurgy)
The ratio of the volume of the loose powder to the volume of the compact made from it.
compressive strength
The maximum compressive stress that a material is capable of developing, based on original area of cross section. If a material fails in compression by a shattering fracture, the compressive strength has a very definite value. If a material does not fail in compression by a shattering fracture, the value obtained for compressive strength is an arbitrary value depending on the degree of distortion that is regarded as indicating complete failure of the material.
compressive stress
A stress that causes an elastic body to deform (shorten) in the direction of the applied load. Contrast with tensile stress.
concentration
(1) The mass of a substance contained in a unit volume of sample, for example, grams per liter. (2) A process for enrichment of an ore in valuable mineral content by separation and removal of waste material, or gangue.
concentration cell
An electrolytic cell, the electromotive force of which is caused by a difference in concentration of some component in the electrolyte. This difference leads to the formation of discrete cathode and anode regions.
concentration polarization
That portion of the polarization of a cell produced by concentration changes resulting from passage of current through the electrolyte.
concurrent heating
The application of supplemental heat to a structure during a welding or cutting operation.
conditioning heat treatment
A preliminary heat treatment used to prepare a material for a desired reaction to a subsequent heat treatment. For the term to be meaningful, the exact heat treatment must be specified.
cone
The conical part of an oxyfuel gas flame next to the orifice of the tip.
cone angle
The angle that the cutter axis makes with the direction along which the blades are moved for adjustment, as in adjustable-blade reamers where the base of the blade slides on a conical surface.
conformal coating
A coating that covers and exactly fits the shape of the coated object.
congruent melting
An isothermal or isobaric melting in which both the solid and liquid phases have the same composition throughout the transformation.
congruent transformation
An isothermal or isobaric phase change in metals in which both of the phases concerned have the same composition throughout the process.
conjugate phases
In microstructural analysis, those states of matter of unique composition that coexist at equilibrium at a single point in temperature and pressure. For example, the two coexisting phases of a two-phase equilibrium.
constant life fatigue diagram
In failure analysis, a plot (usually on rectangular coordinates) of a family of curves, each of which is for a single fatigue life (number of cycles), relating alternating stress, maximum stress, minimum stress, and mean stress. The constant life fatigue diagram is generally derived from a family of S-N curves, each of which represents a different stress ratio for a 50% probability of survival. See also nominal stress , maximum stress , minimum stress , S-N curve , fatigue life , and stress ratio.
constituent
(1) One of the ingredients that make up a chemical system. (2) A phase or a combination of phases that occurs in a characteristic configuration in an alloy microstructure.
constitution diagram
See phase diagram.
constraint
Any restriction that limits the transverse contraction normally associated with a longitudinal tension and that hence causes a secondary tension in the transverse direction; usually used in connection with welding. Contrast with restraint.
consumable electrode
A general term for any arc welding electrode made chiefly of filler metal. Use of specific names such as covered electrode , bare electrode , flux cored electrode , and lightly coated electrode is preferred.
consumable-electrode remelting
A process for refining metals in which an electric current passes between an electrode made of the metal to be refined and an ingot of the refined metal, which is contained in a water-cooled mold. As a result of the passage of electric current, droplets of molten metal form on the electrode and fall to the ingot. The refining action occurs from contact with the atmosphere, vacuum, or slag through which the drop falls. See also electroslag remelting and vacuum arc remelting.
contact corrosion
A term primarily used in Europe to describe galvanic corrosion between dissimilar metals.
contact fatigue
Cracking and subsequent pitting of a surface subjected to alternating Hertzian stresses such as those produced under rolling contact or combined rolling and sliding. The phenomenon of contact fatigue is encountered most often in rolling-element bearings or in gears, where the surface stresses are high due to the concentrated loads and are repeated many times during normal operation.
contact plating
A metal plating process wherein the plating current is provided by galvanic action between the work metal and a second metal, without the use of an external source of current.
contact potential
In corrosion technology, the potential difference at the junction of two dissimilar substances.
container
The chamber into which an ingot or billet is inserted prior to extrusion. The container for backward extrusion of cups or cans is sometimes called a die.
contaminant
An impurity or foreign substance present in a material or environment that affects one or more properties of the material.
continuous casting
A casting technique in which a cast shape is continuously withdrawn through the bottom of the mold as it solidifies, so that its length is not determined by mold dimensions. Used chiefly to produce semifinished mill products such as billets, blooms, ingots, slabs, strip, and tubes. See also strand casting.
continuous cooling transformation (CCT) diagram
Set of curves drawn using logarithmic time and linear temperature as coordinates, which define, for each cooling curve of an alloy, the beginning and end of the transformation of the initial phase.
continuous mill
A rolling mill consisting of a number of strands of synchronized rolls (in tandem) in which metal undergoes successive reductions as it passes through the various strands.
continuous phase
In an alloy or portion of an alloy containing more than one phase, the phase that forms the matrix in which the other phase or phases are dispersed.
continuous precipitation
Precipitation from a supersaturated solid solution in which the precipitate particles grow by long-range diffusion without recrystallization of the matrix. Continuous precipitates grow from nuclei distributed more or less uniformly throughout the matrix. They usually are randomly oriented, but may form a Widmanstätten structure. Also called general precipitation. Compare with discontinuous precipitation and localized precipitation.
continuous-type furnace
A furnace used for heat treating materials that progress continuously through the furnace, entering one door and being discharged from another.
continuous weld
A weld extending continuously from one end of a joint to the other or, where the joint is essentially circular, completely around the joint. Contrast with intermittent weld.
contour forming
See roll forming , stretch forming , tangent bending , and wiper forming.
contour machining
Machining of irregular surfaces, such as those generated in tracer turning, tracer boring, and tracer milling.
contour milling
Milling of irregular surfaces. See also tracer milling.
contraction
The volume change that occurs in metals and alloys upon solidification and cooling to room temperature.
controlled atmosphere
(1) A specified inert gas or mixture of gases at a predetermined temperature in which selected processes take place. (2) As applied to sintering, to prevent oxidation and destruction of the powder compacts.
controlled cooling
Cooling a metal or alloy from an elevated temperature in a predetermined manner to avoid hardening, cracking, or internal damage, or to produce desired microstructure or mechanical properties.
controlled-pressure cycle
A forming cycle during which the hydraulic pressure in the forming cavity is controlled by an adjustable cam that is coordinated with the punch travel.
controlled rolling
A hot-rolling process in which the temperature of the steel is closely controlled, particularly during the final rolling passes, to produce a fine-grain microstructure.
conventional forging
A forging characteristic by design complexity and tolerances that falls within the broad range of general forging practice.
conventional milling
Milling in which the cutter moves in the direction opposite to the feed at the point of contact. Contrast with climb milling.
conventional strain
See engineering strain and strain.
conventional stress
See engineering stress and stress.
conversion coating
A coating consisting of a compound of the surface metal, produced by chemical or electrochemical treatments of the metal. Examples include chromate coatings on zinc, cadmium, magnesium, and aluminum, and oxide and phosphate coatings on steel. See also chromate treatment and phosphating.
converter
A furnace in which air is blown through a bath of molten metal or matte, oxidizing the impurities and maintaining the temperature through the heat produced by the oxidation reaction. A typical converter is the argon oxygen decarburization vessel.
coolant
The liquid used to cool the work during grinding and to prevent it from rusting. It also lubricates, washes away chips and grits, and aids in obtaining a finer finish. In metal cutting, the preferred term is cutting fluid.
cooling curve
A graph showing the relationship between time and temperature during the cooling of a material. It is used to find the temperatures at which phase changes occur. A property or function other than time may occasionally be used–for example, thermal expansion.
cooling rate
The average slope of the time-temperature curve taken over a specified time and temperature interval.
cooling stresses
Residual stresses in castings resulting from nonuniform distribution of temperature during cooling.
cope
In casting, the upper or topmost section of a flask, mold, or pattern.
copper-accelerated salt-spray (CASS) test
An accelerated corrosion test for some electrodeposits and for anodic coatings on aluminum.
copper brazing
A term improperly used to denote brazing with a copper filler metal.
core
(1) A specially formed material inserted in a mold to shape the interior or other part of a casting that cannot be shaped as easily by the pattern. (2) In a ferrous alloy prepared for case hardening, that portion of the alloy that is not part of the case. Typically considered to be the portion that (a) appears dark (with certain etchants) on an etched cross section, (b) has an essentially unaltered chemical composition, or (c) has a hardness, after hardening, less than a specified value.
core assembly
In casting, a complex core consisting of a number of sections.
core binder
In casting, any material used to hold the grains of core sand together.
core blow
A gas pocket in a casting adjacent to a cored cavity and caused by entrapped gases from the core.
core blower
A machine for making foundry cores using compressed air to blow and pack the sand into the core box.
core box
In casting, a wood, metal, or plastic structure containing a shaped cavity into which sand is packed to make a core.
cored bars
In powder metallurgy, a compact of bar shape heated by its own electrical resistance to a temperature high enough to melt its interior.
core forging
(1) Displacing metal with a punch to fill a die cavity. (2) The product of such an operation.
core knockout machine
In casting, a mechanical device for removing cores from castings.
core rod
In powder metallurgy, a member of a die assembly used in molding a hole in a compact.
core sand
In casting, sand for making cores to which a binding material has been added to obtain good cohesion and permeability after drying; usually low in clays.
coring
(1) A condition of variable composition between the center and surface of a unit of microstructure (such as a dendrite, grain, carbide particle); results from nonequilibrium solidification, which occurs over a range of temperature. (2) A central cavity at the butt end of a rod extrusion, sometimes called extrusion pipe.
corona (resistance welding)
The area sometimes surrounding the nugget of a spot weld at the faying surfaces which provides a degree of solid-state welding.
corrodkote test
An accelerated corrosion test for electrodeposits.
corrosion
The chemical or electrochemical reaction between a material, usually a metal, and its environment that produces a deterioration of the material and its properties.
corrosion effect
A change in any part of the corrosion system caused by corrosion.
corrosion embrittlement
The severe loss of ductility of a metal resulting from corrosive attack, usually intergranular and often not visually apparent.
corrosion-erosion
See erosion-corrosion.
corrosion fatigue
The process in which a metal fractures prematurely under conditions of simultaneous corrosion and repeated cyclic loading at lower stress levels or fewer cycles than would be required in the absence of the corrosive environment.
corrosion inhibitor
See inhibitor.
corrosion potential (Ecorr)
The potential of a corroding surface in an electrolyte, relative to a reference electrode. Also called rest potential, open-circuit potential, or freely corroding potential.
corrosion product
Substance formed as a result of corrosion.
corrosion protection
Modification of a corrosion system so that corrosion damage is mitigated.
corrosion rate
Corrosion effect on a metal per unit of time. The type of corrosion rate used depends on the technical system and on the type of corrosion effect. Thus, corrosion rate may be expressed as an increase in corrosion depth per unit of time (penetration rate, for example, mils/yr) or the mass of metal turned into corrosion products per unit area of surface per unit of time (weight loss, for example, g/m2/yr). The corrosion effect may vary with time and may not be the same at all points of the corroding surface. Therefore, reports of corrosion rates should be accompanied by information on the type, time dependency, and location of the corrosion effect.
corrosion resistance
The ability of a material to withstand contact with ambient natural factors or those of a particular, artificially created atmosphere, without degradation or change in properties. For metals, this could be pitting or rusting; for organic materials, it could be crazing.
corrosion system
System consisting of one or more metals and all parts of the environment that influence corrosion.
corrosive wear
Wear in which chemical or electrochemical reaction with the environment is significant. See also oxidative wear.
corrugating
The forming of sheet metal into a series of straight, parallel alternate ridges and grooves with a rolling mill equipped with matched roller dies or a press brake equipped with a specially shaped punch and die.
corrugations
In metalforming, transverse ripples caused by a variation in strip shape during hot or cold reduction.
Cottrell process
Removal of solid particulates from gases with electrostatic precipitation.
coulometer
An electrolytic cell arranged to measure the quantity of electricity by the chemical action produced in accordance with Faraday’s law.
counterblow hammer
A forging hammer in which both the ram and the anvil are driven simultaneously toward each other by air or steam pistons.
counterboring
Removal of material to enlarge a hole for part of its depth with a rotary, pilot guided, end cutting tool having two or more cutting lips and usually having straight or helical flutes for the passage of chips and the admission of a cutting fluid.
countersinking
Beveling or tapering the work material around the periphery of a hole creating a concentric surface at an angle less than 90° with the centerline of the hole for the purpose of chamfering holes or recessing screw and rivet heads.
covered electrode
A composite filler metal electrode consisting of a core of a bare electrode or metal cored electrode to which a covering sufficient to provide a slag layer on the weld metal has been applied. The covering may contain materials providing such functions as shielding from the atmosphere, deoxidation, and arc stabilization and can serve as a source of metallic additions to the weld. Compare with lightly coated electrode.
covering power
(1) The ability of a solution to give satisfactory plating at very low current densities, a condition that exists in recesses and pits. This term suggests an ability to cover, but not necessarily to build up, a uniform coating, whereas throwing power suggests the ability to obtain a coating of uniform thickness on an irregularly shaped object. (2) The degree to which a porcelain enamel coating obscures the underlying surface.
crack
(1) A fracture type discontinuity characterized by a sharp tip and high ratio of length and width to opening displacement. (2) A line of fracture without complete separation.
crack growth
Rate of propagation of a crack through a material due to a static or dynamic applied load.
crack length (depth) (a)
In fatigue and stress-corrosion cracking, the physical crack size used to determine the crack growth rate and the stress-intensity factor. For a compact-type specimen, crack length is measured from the line connecting the bearing points of load application. For a center-crack tension specimen, crack length is measured from the perpendicular bisector of the central crack. See also crack size.
crack mouth opening displacement (CMOD)
See crack opening displacement.
crack opening displacement
On a KIc specimen, the opening displacement of the notch surfaces at the notch and in the direction perpendicular to the plane of the notch and the crack. The displacement at the tip is called the crack tip opening displacement (CTOD); at the mouth, it is called the crack mouth opening displacement (CMOD). See also stress-intensity factor for definition of KIc.
crack size (a)
A lineal measure of a principal planar dimension of a crack. This measure is commonly used in the calculation of quantities descriptive of the stress and displacement fields. In practice, the value of crack size is obtained from procedures for measurement of physical crack size, original crack size, or effective crack size, as appropriate to the situation under consideration. See also crack length (depth).
crack tip opening displacement (CTOD)
See crack opening displacement.
crank press
A mechanical press whose slides are actuated by a crankshaft.
crater
In arc welding, a depression at the termination of a weld bead or in the molten weld pool.
crater crack
A crack in the crater of a weld bead.
crater wear
The wear that occurs on the rake face of a cutting tool due to contact with the material in the chip that is sliding along that face.
craze cracking
Irregular surface cracking of a metal associated with thermal cycling. This term is used more in the United Kingdom than in the United States, where the term checking is used instead. See also checks.
creep
Time-dependent strain occurring under stress. The creep strain occurring at a diminishing rate is called primary creep; that occurring at a minimum and almost constant rate, secondary creep; and that occurring at an accelerating rate, tertiary creep.
creep-feed grinding
A grinding process that produces deeper cuts at slow traverse rates.
creep limit
(1) The maximum stress that will cause less than a specified quantity of creep in a given time. (2) The maximum nominal stress under which the creep strain rate decreases continuously with time under constant load and at constant temperature. Sometimes used synonymously with creep strength.
creep rate
The slope of the creep-time curve at a given time. Deflection with time under a given static load.
creep recovery
The time-dependent decrease in strain in a solid, following the removal of force.
creep-rupture embrittlement
Embrittlement under creep conditions. Failure occurs by intergranular cracking of the embrittled material.
creep-rupture strength
The stress that causes fracture in a creep test at a given time, in a specified constant environment. This is sometimes referred to as the stress-rupture strength.
creep-rupture test
A test in which progressive specimen deformation and the time for rupture are both measured. In general, deformation is much greater than that developed during a creep test. Also known as stress-rupture test.
creep strain
The time-dependent total strain (extension plus initial gage length) produced by applied stress during a creep test.
creep strength
The stress that will cause a given creep strain in a creep test at a given time in a specified constant environment.
creep stress
The constant load divided by the original cross-sectional area of the specimen.
creep test
A method of determining the extension of metals under a given load at a given temperature. The determination usually involves the plotting of time-elongation curves under constant load; a single test may extend over many months. The results are often expressed as the elongation (in millimeters or inches) per hour on a given gage length (e.g., 25 mm, or 1 in.).
crevice corrosion
Localized corrosion of a metal surface at, or immediately adjacent to, an area that is shielded from full exposure to the environment because of close proximity between the metal and the surface of another material.
crimping
The forming of relatively small corrugations in order to set down and lock a seam, to create an arc in a strip of metal, or to reduce an existing arc or diameter. See also corrugating.
critical cooling rate
The minimum rate of continuous cooling for preventing undesirable transformations. For steel, unless otherwise specified, it is the slowest rate at which austenite can be cooled from above critical temperature to prevent its transformation above the martensite start temperature.
critical current density
In an electrolytic process, a current density at which an abrupt change occurs in an operating variable or in the nature of an electrodeposit or electrode film.
critical flaw size
The size of a flaw (defect) in a structure that will cause failure at a particular stress level.
critical point
(1) The temperature or pressure at which a change in crystal structure, phase, or physical properties occurs. Also termed transformation temperature . (2) In an equilibrium diagram, that combination of composition, temperature, and pressure at which the phases of an inhomogeneous system are in equilibrium.
critical shear stress
The shear stress required to cause slip in a designated slip direction on a given slip plane. It is called the critical resolved shear stress if the shear stress is induced by tensile or compressive forces acting on the crystal.
critical strain
(1) In mechanical testing, the strain at the yield point. (2) The strain just sufficient to cause recrystallization; because the strain is small, usually only a few percent, recrystallization takes place from only a few nuclei, which produces a recrystallized structure consisting of very large grains.
critical stress-intensity factor
See stress-intensity factor.
critical temperature
That temperature above which the vapor phase cannot be condensed to liquid by an increase in pressure. Synonymous with critical point if pressure is constant.
critical temperature range
Synonymous with transformation ranges , which is the preferred term.
Croning process
In casting, a shell molding process that uses a phenolic resin binder. Sometimes referred to as C process or Chronizing.
crop
(1) An end portion of an ingot that is cut off as scrap. (2) To shear a bar or billet.
cross breaks
Same as coil breaks.
cross-country mill
A rolling mill in which the mill stands are so arranged that their tables are parallel with a transfer (or crossover) table connecting them. Such a mill is used for rolling structural shapes, rails, and any special form of bar stock not rolled in the ordinary bar mill.
cross direction
See transverse direction.
cross forging
Preliminary working of forging stock in flat dies to develop mechanical properties, particularly in the center portions of heavy sections.
cross rolling
Rolling of metal or sheet or plate so that the direction of rolling is about 90° from the direction of a previous rolling.
cross-wire weld
A weld made at the junction between crossed wires or bars.
crown
(1) The upper part (head) of a forming press frame. On hydraulic presses, the crown usually contains the cylinder; on mechanical presses, the crown contains the drive mechanism. See also hydraulic press and mechanical press . (2) A shape (crown) ground into a flat roll to ensure flatness of cold- (and hot-) rolled sheet and strip. (3) A contour on a sheet or roll where the thickness or diameter increases from edge to center.
crucible furnace
A melting or holding furnace in which the molten metal is contained in a pot-shaped (hemispherical) shell. Electric heaters or fuel-fired burners outside the shell generate the heat that passes through the shell (crucible) to the molten metal.
crush
(1) Buckling or breaking of a section of a casting mold due to incorrect register when the mold is closed. (2) An indentation in the surface of a casting due to displacement of sand when the mold was closed.
crush forming
Shaping a grinding wheel by forcing a rotating metal roll into its face so as to reproduce the desired contour.
crushings test
(1) A radial compressive test applied to tubing, sintered-metal bearings, or other similar products for determining radial crushing strength (maximum load in compression). (2) An axial compressive test for determining quality of tubing, such as soundness of weld in welded tubing.
cryogenic treatment
See cold treatment.
crystal
(1) A solid composed of atoms, ions, or molecules arranged in a pattern that is repetitive in three dimensions. (2) That form, or particle, or piece of a substance in which its atoms are distributed in one specific orderly geometrical array, called a “lattice,” essentially throughout. Crystals exhibit characteristic optical and other properties and growth or cleavage surfaces, in characteristic directions.
crystalline
That form of a substance that comprises predominantly (one or more) crystals, as opposed to glassy or amorphous.
crystalline fracture
A pattern of brightly reflecting crystal facets on the fracture surface of a polycrystalline metal, resulting from cleavage fracture of many individual crystals. Contrast with fibrous fracture , and silky fracture ; see also granular fracture.
crystallization
(1) The separation, usually from a liquid phase on cooling, of a solid crystalline phase. (2) The progressive process in which crystals are first nucleated (started) and then grown in size within a host medium that supplies their atoms. The host may be gas, liquid, or of another crystalline form.
crystal orientation
See orientation.
crystal system
One of seven groups into which all crystals may be divided; triclinic, monoclinic, orthorhombic, hexagonal, rhombohedral, tetragonal, and cubic.
cubic plane
A plane perpendicular to any one of the three crystallographic axes of the cubic (isometric) system; the Miller indices are {100}.
cup
(1) A sheet metal part; the product of the first drawing operation. (2) Any cylindrical part or shell closed at one end.
cup-and-cone-fracture
A mixed-mode fracture, often seen in tensile-test specimens of a ductile material, where the central portion undergoes plane-strain fracture and the surrounding region undergoes plane-stress fracture. It is called a cup fracture (or cup-and-cone fracture) because one of the mating fracture surfaces looks like a miniature cup–that is, it has a central depressed flat-face region surrounded by a shear lip; the other fracture surface looks like a miniature truncated cone.
cupellation
Oxidation of molten lead containing gold and silver to produce lead oxide, thereby separating the precious metals from the base metal.
cupola
A cylindrical vertical furnace for melting metal, especially cast iron, by having the charge come in contact with the hot fuel, usually metallurgical coke.
cupping
(1) The first step in deep drawing. (2) Fracture of severely worked rods or wire where one end has the appearance of a cup and the other that of a cone.
cupping test
A mechanical test used to determine the ductility and stretching properties of sheet metal. It consists of measuring the maximum part depth that can be formed before fracture. The test is typically carried out by stretching the test piece clamped at its edges into a circular die using a punch with a hemispherical end. See also Erichsen test , Olsen ductility test , and Swift cup test.
Curie temperature
The temperature marking the transition between ferromagnetism and paramagnetism, or between the ferroelectric phase and the paraelectric phase. Also known as Curie point. See also ferromagnetism and paramagnetism.
curling
Rounding the edge of sheet metal into a closed or partly closed loop.
current
The net transfer of electric charge per unit time. Also called electric current. See also current density.
current decay
In spot, seam, or projection welding, the controlled reduction of the welding current from its peak amplitude to a lower value to prevent excessively rapid cooling of the weld nugget.
current density
The current flowing to or from a unit area of an electrode surface.
current efficiency
(1) The ratio of the electrochemical equivalent current density for a specific reaction to the total applied current density. (2) The proportion of current used in a given process to accomplish a desired result; in electroplating, the proportion used in depositing or dissolving metal.
cut (foundry practice)
(1) To recondition molding sand by mixing on the floor with a shovel or blade-type machine. (2) To form the sprue cavity in a mold. (3) Defect in a casting resulting from erosion of the sand by metal flowing over the mold or cored surface.
cut edge
A mechanically sheared edge obtained by slitting, shearing, or blanking.
cut-off (casting)
Removing a casting from the sprue by refractory wheel or saw, arc-air torch, or gas torch.
cut-off (metalforming)
A pair of blades positioned in dies or equipment (or a section of the die milled to produce the same effect as inserted blades) used to separate the forging from the bar after forging operations are completed. Used only when forgings are produced from relatively long bars instead of from individual, precut multiples or blanks. See also blank and multiple.
cutoff wheel
A thin abrasive wheel for severing or slotting any material or part.
cutting down
Removing roughness or irregularities of a metal surface by abrasive action.
cutting edge
The leading edge of a cutting tool (such as a lathe tool, drill, or milling cutter) where a line of contact is made with the work during machining.
cutting fluid
A fluid used in metal cutting to improve finish, tool life, or dimensional accuracy. On being flowed over the tool and work, the fluid reduces friction, the heat generated, and tool wear, and prevents galling. It conducts the heat away from the point of generation and also serves to wash the chips away.
cutting speed
The linear or peripheral speed of relative motion between the tool and workpiece in the principal direction of cutting.
cutting tip
That part of an oxygen cutting torch from which the gases issue.
cutting torch (arc)
A device used in air carbon arc cutting, gas tungsten arc cutting, and plasma arc cutting to control the position of the electrode, to transfer current, and to control the flow of gases.
cutting torch (oxyfuel gas)
A device used for directing the preheating flame produced by the controlled combustion of fuel gases and to direct and control the cutting oxygen.
cyanic copper
Copper electrodeposited from an alkali-cyanide solution containing a complex ion made up of univalent copper and the cyanide radical; also the solution itself.
cyanide slimes
Finely divided metallic precipitates that are formed when precious metals are extracted from their ores using cyanide solutions.
cyaniding
A case-hardening process in which a ferrous material is heated above the lower transformation temperature range in a molten salt containing cyanide to cause simultaneous absorption of carbon and nitrogen at the surface and, by diffusion, create a concentration gradient. Quench hardening completes the process.
cycle (N)
In fatigue, one complete sequence of values of applied load that is repeated periodically. See also S-N curve.
cycle annealing
An annealing process employing a predetermined and closely controlled time-temperature cycle to produce specific properties or microstructures.
cyclic load
(1) Repetitive loading, as with regularly recurring stresses on a part, that sometimes leads to fatigue fracture. (2) Loads that change value by following a regular repeating sequence of change.
cylindrical grinding
Grinding the outer cylindrical surface of a rotating part.
cylindrical land
Land having zero relief.