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A method of surface hardening of steel in which parts are packed in a steel box with a carburizing compound and heated to elevated temperatures. This process has been largely supplanted by gas and liquid carburizing processes.
A method of surface hardening of steel in which parts are packed in a steel box with a nitriding compound and heated to elevated temperatures.
Hot rolling a pack of two or more sheets of metal; scale prevents their being welded together.
A rough forged shape, usually flat, that can be obtained quickly with minimal tooling. Considerable machining is usually required to attain the finish size.
pancake grain structure
A metallic structure in which the lengths and widths of individual grains are large compared to their thicknesses.
(1) A material whose specific permeability is greater than unity and is practically independent of the magnetizing force. (2) Material with a small positive susceptibility due to the interaction and independent alignment of permanent atomic and electronic magnetic moments with the applied field. Compare with ferromagnetic material.
A property exhibited by substances that, when placed in a magnetic field, are magnetized parallel to the field to an extent proportional to the field (except at very low temperatures or in extremely large magnetic fields). Compare with ferromagnetism.
A process used to recover precious metals from lead and based on the principle that if 1 to 2% Zn is stirred into the molten lead, a compound of zinc with gold and silver separates out and can be skimmed off.
An imprecise term used to denote a treatment given cold-worked metallic material to reduce its strength to a controlled level or to effect stress relief. To be meaningful, the type of material, the degree of cold work, and the time-temperature schedule must be stated.
The appearance of a metal particle, such as spherical, rounded, angular, acicular, dendritic, irregular, porous, fragmented, blocky, rod, flake, nodular, or plate.
The controlling lineal dimension of an individual particle as determined by analysis with screens or other suitable instruments. See also sieve analysis and sieve classification.
particle size distribution
The percentage, by weight or by number, of each fraction into which a powder or sand sample has been classified with respect to sieve number or particle size.
Segregation of granular material into specified particle size ranges.
(1) In the recovery of precious metals, the separation of silver from gold. (2) The zone of separation between cope and drag portions of the mold or flask in sand casting. (3) A composition sometimes used in sand molding to facilitate the removal of the pattern. (4) Cutting simultaneously along two parallel lines or along two lines that balance each other in side thrust. (5) A shearing operation used to produce two or more parts from a stamping.
A material dusted or sprayed on foundry (casting) patterns to prevent adherence of sand and to promote easy separation of cope and drag parting surfaces when the cope is lifted from the drag.
(1) The intersection of the parting plane of a casting or plastic mold or the parting plane between forging dies with the mold or die cavity. (2) A raised line or projection on the surface of a casting, plastic part, or forging that corresponds to said intersection.
(1) In forging, the dividing line between dies. (2) In casting, the dividing line between mold halves.
In foundry practice, a fine sand for dusting on sand mold surfaces that are to be separated.
(1) A single transfer of metal through a stand of rolls. (2) The open space between two grooved rolls through which metal is processed. (3) The weld metal deposited in one trip along the axis of a weld. See also weld pass.
(1) A reduction of the anodic reaction rate of an electrode involved in corrosion. (2) The process in metal corrosion by which metals become passive. (3) The changing of a chemically active surface of a metal to a much less reactive state. Contrast with activation.
(1) A metal corroding under the control of a surface reaction product. (2) The state of the metal surface characterized by low corrosion rates in a potential region that is strongly oxidizing for the metal.
A corrosion cell in which the anode is a metal in the active state and the cathode is the same metal in the passive state.
A condition in which a piece of metal, because of an impervious covering of oxide or other compound, has a potential much more positive than that of the metal in the active state.
In wiremaking, a heat treatment applied to medium- or high-carbon steel before drawing of wire or between drafts. This process consists of heating to a temperature above the transformation range and then cooling to a temperature below Ae1 in air or in a bath of molten lead or salt.
Same as stretcher leveling.
The coating, usually green, that forms on the surface of metals such as copper and copper alloys exposed to the atmosphere. Also used to describe the appearance of a weathered surface of any metal.
(1) A form of wood, metal, or other material around which molding material is placed to make a mold for casting metals. (2) A form of wax- or plastic-base material around which refractory material is placed to make a mold for casting metals. (3) A full-scale reproduction of a part used as a guide in cutting.
A metastable lamellar aggregate of ferrite and cementite resulting from the transformation of austenite at temperatures above the bainite range.
See malleable iron.
A microstructure resembling that of the pearlite constituent in steel. Therefore, it is a lamellar structure of varying degrees of coarseness.
The detaching of one layer of a coating from another, or from the substrate, because of poor adherence.
A destructive method of inspection that mechanically separates a lap joint by peeling.
Mechanical working of metal by hammer blows or shot impingement.
A liquid with low surface tension used in liquid penetrant inspection to flow into surface openings of parts being inspected.
See preferred term liquid penetrant inspection.
(1) In founding, an imperfection on a casting surface caused by metal running into voids between sand grains; usually referred to as metal penetration. (2) In welding, the distance from the original surface of the base metal to that point at which fusion ceased.
Same as indentation hardness.
A resistance welding process that produces coalescence of abutting surfaces using heat from an arc produced by a rapid discharge of electrical energy. Pressure is applied percussively during or immediately following the electrical discharge.
The punching of many holes, usually identical and arranged in a regular pattern, in a sheet, workpiece blank, or previously formed part. The holes are usually round, but may be any shape. The operation is also called multiple punching. See also piercing.
Milling a surface parallel to the axis of the cutter.
An isothermal reversible reaction in metals in which a liquid phase reacts with a solid phase to produce a single (and different) solid phase on cooling.
An isothermal reversible reaction in which a solid phase reacts with a second solid phase to produce a single (and different) solid phase on cooling.
permanent magnet material
A ferromagnetic alloy capable of being magnetized permanently because of its ability to retain induced magnetization and magnetic poles after removal of externally applied fields; an alloy with high coercive force. The name is based on the fact that the quality of the early permanent magnets was related to their hardness.
A metal, graphite, or ceramic mold (other than an ingot mold) of two or more parts that is used repeatedly for the production of many castings of the same form. Liquid metal is usually poured in by gravity.
The deformation remaining after a specimen has been stressed a prescribed amount in tension, compression, or shear for a specified time period and released for a specified time period. For creep tests, the residual unrecoverable deformation after the load causing the creep has been removed for a substantial and specified period of time. Also, the increase in length, expressed as a percentage of the original length, by which an elastic material fails to return to its original length after being stressed for a standard period of time.
(1) The passage or diffusion (or rate of passage) of a gas, vapor, liquid, or solid through a material (often porous) without physically or chemically affecting it; the measure of fluid flow (gas or liquid) through a material. (2) A general term used to express various relationships between magnetic induction and magnetizing force. These relationships are either “absolute permeability,” which is a change in magnetic induction divided by the corresponding change in magnetizing force, or “specific (relative) permeability,” the ratio of the absolute permeability to the permeability of free space. (3) In metal casting, the characteristics of molding materials that permit gases to pass through them. “Permeability number” is determined by a standard test.
A tin-base white metal containing antimony and copper. Originally, pewter was defined as an alloy of tin and lead, but to avoid toxicity and dullness of finish, lead is excluded from modern pewter. These modern compositions contain 1 to 8% Sb and 0.25 to 3% Cu.
The negative logarithm of the hydrogen-ion activity; it denotes the degree of acidity or basicity of a solution. At 25 °C (77 °F), 7.0 is the neutral value. Decreasing values below 7.0 indicates increasing acidity; increasing values above 7.0, increasing basicity. The pH values range from 0 to 14.
A physically homogeneous and distinct portion of a material system.
The transition from one physical state to another, such as gas to liquid, liquid to solid, gas to solid, or vice versa.
A graphical representation of the temperature and composition limits of phase fields in an alloy or ceramic system as they actually exist under the specific conditions of heating or cooling. A phase diagram may be an equilibrium diagram, an approximation to an equilibrium diagram, or a representation of metastable conditions or phases. Synonymous with constitution diagram. Compare with equilibrium diagram.
The maximum number of phases (P) that may coexist at equilibrium is two, plus the number of components (C) in the mixture, minus the number of degrees of freedom (F): P + F = C + 2.
Forming an adherent phosphate coating on a metal by immersion in a suitable aqueous phosphate solution. Also called phosphatizing. See also conversion coating.
General term applied to copper deoxidized with phosphorus. The most commonly used deoxidized copper.
An optical method for evaluating the magnitude and distribution of stresses, using a transparent model of a part, or a thick film of photoelastic material bonded to a real part.
A macrograph produced by photographic means.
A micrograph produced by photographic means.
physical crack size (ap)
In fracture mechanics, the distance from a reference plane to the observed crack front. This distance may represent an average of several measurements along the crack front. The reference plane depends on the specimen form, and it is normally taken to be either the boundary or a plane containing either the load line or the centerline of a specimen or plate.
The science and technology dealing with the properties of metals and alloys, and of the effects of composition, processing, and environment on those properties.
Properties of a material that are relatively insensitive to structure and can be measured without the application of force; for example, density, electrical conductivity, coefficient of thermal expansion, magnetic permeability, and lattice parameter. Does not include chemical reactivity. Compare with mechanical properties.
Methods used to determine the entire range of the material’s physical properties of a material. In addition to density and thermal, electrical, and magnetic properties, physical testing methods may be used to assess simple fundamental physical properties such as color, crystalline form, and melting point.
physical vapor deposition (PVD)
A coating process whereby the deposition species are transferred and deposited in the form of individual atoms or molecules. The most common PVD methods are sputtering and evaporation. Sputtering, which is the principal PVD process, involves the transport of a material from a source (target) to a substrate by means of the bombardment of the target by gas ions that have been accelerated by a high voltage. Evaporation, which was the first PVD process used, involves the transfer of material to form a coating by physical means alone, essentially vaporization. Physical vapor deposition coatings are used to improve the wear, friction, and hardness properties of cutting tools and as corrosion-resistant coatings.
A spent acid-pickling bath.
Discoloration of metal due to chemical cleaning without adequate washing and drying.
The chemical removal of surface oxides (scale) and other contaminants such as dirt from iron and steel by immersion in an aqueous acid solution. The most common pickling solutions are sulfuric and hydrochloric acids.
An automatic device for removing a finished part from the press die after it has been stripped.
(1) Transfer of metal from tools to part or from part to tools during a forming operation. (2) Small particles of oxidized metal adhering to the surface of a mill product.
A process for production of magnesium by reduction of magnesium oxide with ferrosilicon.
The general term for cutting (shearing or punching) openings, such as holes and slots, in sheet material, plate, or parts. This operation is similar to blanking; the difference is that the slug or pierce produced by piercing is scrap, while the blank produced by blanking is the useful part.
The reversible interaction, exhibited by some crystalline materials, between an elastic strain and an electric field. The direction of the strain depends on the polarity of the field or vice versa. Compare with electrostrictive effect.
A metal casting used in remelting.
(1) High-carbon iron made by reduction of iron ore in the blast furnace. (2) Cast iron in the form of pigs.
Pilger tube-reducing process
See tube reducing.
pin (for bend testing)
The plunger or tool used in making semiguided, guided, or wraparound bend tests to apply the bending force to the inside surface of the bend. In free bends or semiguided bends to an angle of 180°, a shim or block of the proper thickness may be placed between the legs of the specimen as bending is completed. This shim or block is also referred to as a pin or mandrel. See also mandrel.
Surface disturbances on metal sheet or strip that result from rolling processes and that ordinarily appear as fernlike ripples running diagonally to the direction of rolling.
A pass of sheet metal through rolls to effect a very small reduction in thickness.
The trimming of the edge of a tubular metal part or shell by pushing or pinching the flange or lip over the cutting edge of a stationary punch or over the cutting edge of a draw punch.
pin expansion test
A test for determining the ability of a tube to be expanded or for revealing the presence of cracks or other longitudinal weaknesses, made by forcing a tapered pin into the open end of the tube.
Porosity consisting of numerous small gas holes (pinholes) distributed throughout the metal; found in weld metal, castings, and electrodeposited metal.
See Lüders lines.
(1) The central cavity formed by contraction in metal, especially ingots, during solidification. (2) An imperfection in wrought or cast products resulting from such a cavity. (3) A tubular metal product, cast or wrought. See also extrusion pipe.
A tap for making internal pipe threads within pipe fittings or holes.
Internal or external machine threads, usually tapered, of a design intended for making pressure-tight mechanical joints in piping systems.
A small, regular or irregular crater in the surface of a material created by exposure to the environment, for example, corrosion, wear, or thermal cycling. See also pitting.
(1) Forming small sharp cavities in a surface by corrosion, wear, or other mechanically assisted degradation. (2) Localized corrosion of a metal surface, confined to a point or small area, that takes the form of cavities.
The stress condition in linear elastic fracture mechanics in which there is zero strain in a direction normal to both the axis of applied tensile stress and the direction of crack growth (that is, parallel to the crack front); most nearly achieved in loading thick plates along a direction parallel to the plate surface. Under plane-strain conditions, the plane of fracture instability is normal to the axis of the principal tensile stress.
plane-strain fracture toughness (KIc)
The crack extension resistance under conditions of crack-tip plane strain. See also stress-intensity factor.
The stress condition in linear elastic fracture mechanics in which the stress in the thickness direction is zero; most nearly achieved in loading very thin sheet along a direction parallel to the surface of the sheet. Under plane-stress conditions, the plane of fracture instability is inclined 45° to the axis of the principal tensile stress.
plane-stress fracture toughness (Kc)
In linear elastic fracture mechanics, the value of the crack-extension resistance at the instability condition determined from the tangency between the R-curve and the critical crack-extension force curve of the specimen. See also stress-intensity factor.
A method of measuring grain size in which the grains within a definite area are counted.
Producing flat surfaces by linear reciprocal motion of work and the table to which it is attached, relative to a stationary single-point cutting tool.
Producing a smooth finish on metal by a rapid succession of blows delivered by highly polished dies or by a hammer designed for the purpose, or by rolling in a planishing mill.
plasma arc cutting
An arc cutting process that severs metals by melting a localized area with heat from a constricted arc and removing the molten metal with a high-velocity jet of hot, ionized gas issuing from the plasma torch.
plasma arc welding (PAW)
An arc welding process that produces coalescence of metals by heating them with a constricted arc between an electrode and the workpiece (transferred arc) or the electrode and the constricting nozzle (nontransferred arc). Shielding is obtained from hot, ionized gas issuing from an orifice surrounding the electrode and may be supplemented by an auxiliary source of shielding gas, which may be an inert gas or a mixture of gases. Pressure may or may not be used, and filler metal may or may not be supplied.
plasma-assisted chemical vapor deposition
A chemical vapor deposition process that uses low-pressure glow-discharge plasmas to promote the chemical deposition reactions. Also called plasma-enhanced chemical vapor deposition.
Same as ion carburizing.
Same as ion nitriding.
A thermal spraying process in which a nontransferred arc of a plasma torch is utilized to create a gas plasma that acts as the source of heat for melting and propelling the surfacing material to the substrate.
Molding in which a gypsum-bonded aggregate flour in the form of a water slurry is poured over a pattern, permitted to harden, and, after removal of the pattern, thoroughly dried. This technique is used to make smooth nonferrous castings of accurate size.
The permanent (inelastic) distortion of materials under applied stresses that strain the material beyond its elastic limit.
The phenomenon that takes place when metals are stretched or compressed permanently without rupture.
The property of a material that allows it to be repeatedly deformed without rupture when acted upon by a force sufficient to cause deformation and that allows it to retain its shape after the applied force has been removed.
plastic-strain ratio (r-value)
In formability testing of metals, the ratio of the true width strain to the true thickness strain in a sheet tensile test, r = wt. A formability parameter that relates to drawing, it is also known as the anisotropy factor. A high r-value indicates a material with good drawing properties.
A flat-rolled metal product of some minimum thickness and width arbitrarily dependent on the type of metal. Plate thicknesses commonly range from 6 to 300 mm (0.25 to 12 in.); widths from 200 to 2000 mm (8 to 80 in.).
Martensite formed partly in steel containing more than approximately 0.5% C and solely in steel containing more than approximately 1.0% C that appears as lenticular-shape plates (crystals).
(1) The sliding member, slide, or ram of a metal forming press. (2) A part of a resistance welding, mechanical testing, or other machine with a flat surface to which dies, fixtures, backups, or electrode holders are attached and that transmits pressure or force.
Forming an adherent layer of metal on an object; often used as a shop term for electroplating. See also electrodeposition and electroless plating.
A fixture used to hold work and conduct current to it during electroplating.
(1) A rod or mandrel over which a pierced tube is forced. (2) A rod or mandrel that fills a tube as it is drawn through a die. (3) A punch or mandrel over which a cup is drawn. (4) A protruding portion of a die impression for forming a corresponding recess in the forging. (5) A false bottom in a die.
A tap with chamfer extending from three to five threads.
A weld made in a circular hole in one member of a joint, fusing that member to another member.
A special quality of powdered graphite used to coat molds and, in a mixture of clay, to make crucibles.
Grinding wherein the only relative motion of the wheel is radially toward the work.
The powder sample retained on a screen of stated size, identified by the retaining mesh number. See also sieve analysis and sieve classification.
The portion of a sample of a granular substance (such as metal powder) retained on a standard sieve of specified number. Contrast with minus sieve. See also sieve analysis and sieve classification.
Sheet consisting of bonded layers of dissimilar metals.
The acronym for powder metallurgy.
A press that uses air or a gas to deliver the pressure to the upper and lower rams.
In general, the angle at the point of a cutting tool. Most commonly, the included angle at the point of a twist drill, the general-purpose angle being 118°.
Poisson’s ratio ()
The absolute value of the ratio of transverse (lateral) strain to the corresponding axial strain resulting from uniformly distributed axial stress below the proportional limit of the material.
See direct current electrode negative and direct current electrode positive.
(1) The change from the open-circuit electrode potential as the result of the passage of current. (2) A change in the potential of an electrode during electrolysis, such that the potential of an anode becomes more noble, and that of a cathode more active, than their respective reversible potentials. Often accomplished by formation of a film on the electrode surface.
A plot of current density versus electrode potential for a specific electrode-electrolyte combination.
(1) A means of designating the orientation of a crystal plane by stereographically plotting its normal. For example, the north pole defines the equatorial plane. (2) Either of the two regions of a permanent magnet or electromagnet where most of the lines of induction enter or leave.
A stereoscopic projection of a polycrystalline aggregate showing the distribution of poles, or plane normals, of a specific crystalline plane, using specimen axes as reference axes. Pole figures are used to characterize preferred orientation in polycrystalline materials.
(1) Smoothing metal surfaces, often to a high luster, by rubbing the surface with a fine abrasive, usually contained in a cloth or other soft lap. Results in microscopic flow of some surface metal together with actual removal of a small amount of surface metal. (2) Removal of material by the action of abrasive grains carried to the work by a flexible support, generally either a wheel or a coated abrasive belt. (3) A mechanical, chemical, or electrolytic process or combination thereof used to prepare a smooth, reflective surface suitable for microstructural examination that is free of artifacts or damage introduced during prior sectioning or grinding. See also electrolytic polishing and electropolishing.
Pertaining to a solid comprised of many crystals or crystallites, intimately bonded together. May be homogeneous (one substance) or heterogeneous (two or more crystal types or compositions).
A general term for the ability of a solid to exist in more than one form. In metals, alloys, and similar substances, this usually means the ability to exist in two or more crystal structures, or in an amorphous state and at least one crystal structure. See also allotropy , enantiotropy , and monotropism.
Loss of small portions of a porcelain enamel coating. The usual cause is outgassing of hydrogen or other gases from the substrate during firing, but pop-off may also occur because of oxide particles or other debris on the surface of the substrate. Usually, the pits are minute and cone shaped, but when pop-off is the result of severe fishscale the pits may be much larger and irregular.
A substantially vitreous or glassy, inorganic coating (borosilicate glass) bonded to metal by fusion at a temperature above 425 °C (800 °F). Porcelain enamels are applied primarily to components made of sheet iron or steel, cast iron, aluminum, or aluminum-coated steels.
(1) A small opening, void, interstice, or channel within a consolidated solid mass or agglomerate, usually larger than atomic or molecular dimensions. (2) A minute cavity in a powder metallurgy compact, sometimes added intentionally. (3) A minute perforation in an electroplated coating.
(1) Fine holes or pores within a solid; the amount of these pores is expressed as a percentage of the total volume of the solid. (2) Cavity-type discontinuities in weldments formed by gas entrapment during solidification. (3) A characteristic of being porous, with voids or pores resulting from trapped air or shrinkage in a casting. See also gas porosity and pinhole porosity.
Heating weldments immediately after welding, for tempering, for stress relieving, or for providing a controlled rate of cooling to prevent formation of a hard or brittle structure. See also postweld heat treatment.
postweld heat treatment
Any heat treatment that follows the welding operation.
(1) A vessel for holding molten metal. (2) The electrolytic reduction cell used to make such metals as aluminum from a fused electrolyte.
Same as box annealing.
(1) Any of various functions from which intensity or velocity at any point in a field may be calculated. (2) The driving influence of an electrochemical reaction.
A term used in the automotive industry to describe the corrosion of vehicle body parts due to the collection of road salts and debris on ledges and in pockets that are kept moist by weather and washing. Also called deposit corrosion or attack.
The transfer of molten metal from furnace to ladle, ladle to ladle, or ladle into molds.
In metal casting, a basin on top of a mold that receives the molten metal before it enters the sprue or downgate.
An aggregate of discrete particles that are usually in the size range of 1 to 1000 m.
See preferred terms chemical flux cutting and metal powder cutting.
powder flame spraying
A thermal spraying process variation in which the material to be sprayed is in powder form.
The plastic deformation of a powder metallurgy compact or preform into a fully dense finished shape by using compressive force; usually done hot and within closed dies.
In powder metallurgy, an agent or component incorporated into a mixture to facilitate compacting and ejecting of the compact from its mold.
powder metallurgy (P/M)
The technology and art of producing metal powders and utilizing metal powders for production of massive materials and shaped objects.
powder metallurgy forging
See powder forging.
powder metallurgy part
A shaped object that has been formed from metal powders and sintered by heating below the melting point of the major constituent. A structural or mechanical component made by the powder metallurgy process.
A metallic powder composed of two or more elements that are alloyed in the powder manufacturing process and in which the particles are of the same nominal composition throughout.
Relatively scarce, highly corrosion resistant, valuable metals found in periods 5 and 6 (groups VIII and Ib) of the periodic table. They include ruthenium, rhodium, palladium, silver, asmium, iridium, platinum, and gold. See also noble metal.
In metals, the separation of a new phase from solid or liquid solution, usually with changing conditions of temperature, pressure, or both.
Hardening in metals caused by the precipitation of a constituent from a supersaturated solid solution. See also age hardening and aging.
precipitation heat treatment
Artificial aging of metals in which a constituent precipitates from a supersaturated solid solution.
A metal casting of reproducible, accurate dimensions, regardless of how it is made. Often used interchangeably with investment casting.
A forging produced to closer tolerances than normally considered standard by the industry. With precision forging, a net shape, or at least a near-net shape, can be produced in the as-forged condition. See also net shape.
Machine grinding to specified dimensions and low tolerances.
(1) In investment casting, a special refractory slurry applied to a wax or plastic expendable pattern to form a thin coating that serves as a desirable base for application of the main slurry. See also investment casting. (2) To make the thin coating. (3) The thin coating itself.
precoated metal products
Mill products that have a metallic, organic, or conversion coating applied to their surfaces before they are fabricated into parts.
A mechanical test specimen that is notched and subjected to alternating stresses until a crack has developed at the root of the notch.
A condition of a polycrystalline aggregate in which the crystal orientations are not random, but rather exhibit a tendency for alignment with a specific direction in the bulk material, commonly related to the direction of working. See also texture.
(1) The initial pressing of a metal powder to form a compact that is to be subjected to a subsequent pressing operation other than coining or sizing. (2) Preliminary forming operations, especially for impression-die forging.
(1) Heating before some further thermal or mechanical treatment. For tool steel, heating to an intermediate temperature immediately before final austenitizing. For some nonferrous alloys, heating to a high temperature for a long time, in order to homogenize the structure before working. (2) In welding and related processes, heating to an intermediate temperature for a short time immediately before welding, brazing, soldering, cutting, or thermal spraying. (3) In powder metallurgy, an early stage in the sintering procedure when, in a continuous furnace, lubricant or binder burnoff occurs without atmosphere protection prior to actual sintering in the protective atmosphere of the high heat chamber.
Heating a powder metallurgy compact to a temperature below the final sintering temperature, usually to increase the ease of handling or shaping of a compact or to remove a lubricant or binder (burnoff) prior to sintering.
A machine tool having a stationary bed and a slide or ram that has reciprocating motion at right angles to the bed surface, the slide being guided in the frame of the machine. See also hydraulic press , mechanical press , and slide.
An open-frame single-action press used to bend, blank, corrugate, curl, notch, perforate, pierce, or punch sheet metal or plate.
A metalforming process in which the workpiece is placed over an open die and pressed down into the die by a punch that is actuated by the ram portion of a press brake. The process is most widely used for the forming of relatively long, narrow parts that are not adaptable to press forming and for applications in which production quantities are too small to warrant the tooling cost for contour roll forming.
The weight per unit volume of an unsintered compact. Same as green density.
Any sheet metalforming operation performed with tooling by means of a mechanical or hydraulic press.
The clear distance (left to right) between housings, stops, gibs, gibways, or shoulders of strain rods, multiplied by the total distance from front to back on the bed of a metalforming press. Sometimes called working area.
A rupture in a green powder metallurgy compact that develops during ejection of the compact from the die. Sometimes referred to as a slip crack.
A quench in which hot dies are pressed and aligned with a part before the quenching process begins. Then the part is placed in contact with a quenching medium in a controlled manner. This process avoids part distortion.
(1) Making castings with pressure on the molten or plastic metal, as in die casting, centrifugal casting, cold chamber pressure casting, and squeeze casting. (2) A casting made with pressure applied to the molten or plastic metal.
A resistance welding process variation in which a number of spot or projection welds are made with several electrodes functioning progressively under the control of a pressure-sequencing device.
pressure gas welding
An oxyfuel gas welding process that produces coalescence simultaneously over the entire area of abutting surfaces by heating them with gas flames obtained from combustion of a fuel gas with oxygen and by application of pressure, without the use of filler metal.
A hot-pressing technique that usually employs low loads, high sintering temperatures, continuous or discontinuous sintering, and simple molds to contain the powder. Although the terms pressure sintering and hot pressing are used interchangeably, distinct differences exist between the two processes. In pressure sintering, the emphasis is on thermal processing; in hot pressing, applied pressure is the main process variable.
See preferred terms cold welding , diffusion welding , forge welding , hot pressure welding , pressure-controlled welding , pressure gas welding , and solid-state welding.
The first, or initial, stage of creep, or time-dependent deformation.
The first type of crystals that separate from a melt during solidification.
Metal extracted from minerals and free of reclaimed metal scrap. Compare with native metal.
A mill for rolling ingots or the rolled products of ingots to blooms, billets, or slabs. This type of mill is often called a blooming mill and sometimes called a cogging mill.
principal stress (normal)
The maximum or minimum value of the normal stress at a point in a plane considered with respect to all possible orientations of the considered plane. On such principal planes the shear stress is zero. There are three principal stresses on three mutually perpendicular planes. The state of stress at a point may be (1) uniaxial, a state of stress in which two of the three principal stresses are zero, (2) biaxial, a state of stress in which only one of the three principal stresses is zero, and (3) triaxial, a state of stress in which none of the principal stresses is zero. Multiaxial stress refers to either biaxial or triaxial stress.
A heat treatment used to soften metal for further cold working. In ferrous sheet and wire industries, heating to a temperature close to but below the lower limit of the transformation range and subsequently cooling for working. In the nonferrous industries, heating above the recrystallization temperatures at a time and temperature sufficient to permit the desired subsequent cold working.
The science and technology of winning metals from their ores and purifying metals; sometimes referred to as chemical metallurgy. Its two chief branches are extractive metallurgy and refining.
Particles of a phase in ferrous alloys that precipitate during cooling after austenitizing but before the eutectoid transformation takes place. See also eutectoid.
Any operation that produces an irregular contour on a workpiece, for which a tracer or template-controlled duplicating equipment usually is employed.
Aging by increasing the temperature in steps or continuously during the aging cycle. See also aging and compare with interrupted aging and step aging.
A die with two or more stations arranged in line for performing two or more operations on a part; one operation is usually performed at each station.
Sequential forming at consecutive stations with a single die or separate dies.
A resistance welding process that produces coalescence of metals with the heat obtained from resistance to electric current through the work parts held together under pressure by electrodes. The resulting welds are localized at predetermined points by projections, embossments, or intersections.
(1) To test a component or system at its peak operating load or pressure. (2) Any reproduction of a die impression in any material; often a lead or plaster cast. See also die proof.
A predetermined load, generally some multiple of the service load, to which a specimen or structure is submitted before acceptance for use.
(1) A specified stress to be applied to a member or structure to indicate its ability to withstand service loads. (2) The stress that will cause a specified small permanent set in a material.
The greatest stress a material is capable of developing without a deviation from straight-line proportionality between stress and strain. See also elastic limit and Hooke’s law.
(1) A gas or vacuum envelope surrounding the part to be brazed, welded, or thermal sprayed, with the gas composition controlled with respect to chemical composition, dew point, pressure, flow rate, and so forth. Examples are inert gases, combusted fuel gases, hydrogen, and vacuum. (2) The atmosphere in a heat treating or sintering furnace designed to protect the parts or compacts from oxidation, nitridation, or other contamination from the environment.
(1) A three-component or ternary alloy system in which an intermediate phase acts as a component. (2) A vertical section through a ternary diagram.
Wrinkling or buckling in a drawn shell in an area originally inside the draw ring.
In a casting, cracks that are caused by residual stresses produced during cooling and that result from the shape of the object.
The process of reducing metal powder particle sizes by mechanical means; also called comminution or mechanical disintegration.
(1) The male part of a die–as distinguished from the female part, which is called the die. The punch is usually the upper member of the complete die assembly and is mounted on the slide or in a die set for alignment (except in the inverted die). (2) In double-action draw dies, the punch is the inner portion of the upper die, which is mounted on the plunger (inner slide) and does the drawing. (3) The act of piercing or punching a hole. Also referred to as punching. (4) The movable tool that forces material into the die in powder molding and most metalforming operations. (5) The movable die in a trimming press or a forging machine. (6) The tool that forces the stock through the die in rod and tube extrusion and forms the internal surface in can or cup extrusion.
(1) The die shearing of a closed contour in which the sheared out sheet metal part is scrap. (2) Producing a hole by die shearing, in which the shape of the hole is controlled by the shape of the punch and its mating die. Multiple punching of small holes is called perforating. See also piercing.
(1) In general, any mechanical press. (2) In particular, an endwheel gap-frame press with a fixed bed, used in piercing.
The radius on the end of the punch that first contacts the work, sometimes called nose radius.
Equipment used for drawing moderately heavy-gage tubes by cupping sheet metal and forcing it through a die by pressure exerted against the inside bottom of the cup.
A type of continuous furnace in which parts to be heated are periodically charged into the furnace in containers, which are pushed along the hearth against a line of previously charged containers thus advancing the containers toward the discharge end of the furnace, where they are removed.
Spot or projection welding in which the force is applied manually to one electrode, and the work or backing plate takes the place of the other electrode.
In noncubic crystals, any plane that intersects all three axes.
High-temperature winning or refining of metals.
A device for measuring temperatures above the range of liquid thermometers.
A powder whose particles self-ignite and burn when exposed to oxygen or air.