Glossary - Metallurgical Terms

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Glossary - Metallurgical Terms

Text of Glossary - Metallurgical Terms

  • abrasionThe displacement and/or detachment of metallic particles from a surface from exposure to flowing solids, fluids or gases.

    abrasiveAny substance used for abrading, such as grinding, polishing, blasting, etc. Material may be bonded to form wheels, bricks and files or applied to paper and cloth by means of glue. Natural abrasives include emery, corundum, garnet, sand, etc. Main manufactured abrasives are silicon carbide and aluminum oxide. Metallic shot and grit are also used as abrasives in cleaning castings.

    acicular structureA microstructure characterized by needle-shaped constituents.

    acidA chemical term to define a material that gives an acid reaction.

    acid bottom or lining (furnace)The inner bottom or lining of a melting furnace composed of materials having an acid reaction. Materials may be sand, siliceous rock or silica brick.

    acid meltingMelting in a furnace with refractory material that has an acid reaction, material may be silica sand, siliceous rock or silica brick.

    acid steelSteel melted in a furnace that has an acid bottom and lining, under a predominantly siliceous slag.

    additivesAny material added to molding sand for reasons other than bonding or improvement of bond is considered an additive. Bonds can be of varying types: carbonaceous (seacoal pitch, fuel oil, graphite, Gilsonite): cellulose (wood flour, cereal hulls); fines (silica flour, iron oxide, fly ash); cereals (corn flour, dextrin, sugar); and chemical (boric acid, sulfur, ammonium compounds, diethylene glycol).

    aeratorA device for fluffing (or decreasing the density of) and cooling sand by the admixture of air.

    AFS grain fineness number (gfn)The approximate number of meshes per inch in a sieve that allow a sample to pass through if the sand grains were uniform in size. In other words, it is the average of the grains in the sand sample.

    agingA change in properties of metals and alloys that occurs slowly at room temperature and will proceed rapidly at higher temperatures. The change in properties is often, but not always, due to a phase change (precipitation), but never involves a change in chemical composition of the metal or alloy.

    air channelA groove or hole which carries the vent from a core to the outside of a mold.

    air control equipmentAny device used to regulate the volume, pressure or weight of air.

    air dried (dry)A core or mold dried in air, without application of heat.

    air furnaceA form ofreverberatory furnace for melting ferrous and nonferrous

  • metals and alloys. Flame from fuel burning at one end of the hearth passes over the bath to the stack at the opposite end of the furnace.

    air hammerChipping hammer operated by compressed air air hardeningFull hardening of a metal or alloy during cooling in air or other

    gaseous medium from a temperature above its transformation range.

    air hoistLifting device operated by compressed air.

    air holeA hole in a casting caused by gas trapped in the metal during solidification.

    air injection machineAn early type of diecasting machine in which air pressure acting directly on the surface of molten metal in a closed gooseneck forces the metal into the die.

    air settingThe property of some materials to take a permanent set at normal air temperature Examples are gypsum slurry, investment-molding materials, core and mold washes, etc.

    airless blast cleaningA process whereby the abrasive material is applied to the object being cleaned by centrifugal force generated by a rotating-vane-type wheel.

    allotropyOccurrence of an element in two or more modifications. For example, carbon occurs in nature as the hard crystalline diamond, soft flaky crystalline graphite and amorphous coal.

    alloyA substance having metallic properties and composed of two or more chemical elements of which at least one is metal. Usually possesses qualities different from those of the components.

    alloyingProcedure of adding elements other than those usually comprising a metal or alloy to change its characteristics and properties.

    alloying elementsElements added to nonferrous and ferrous metals and alloys to change their characteristics and properties.

    alpha ironAn allotropic (polymorphic) form of iron, which is magnetic and whose atomic structure is body-centered-cubic lattice. It is soft, ductile, of fair strength and is capable of dissolving a few hundredths of a percent of carbon to form a solid solution.

    aluminum(Al) A metallic element. The atomic weight is 26.98 and melting point is 660C.

    amorphousHaving no crystalline form.

    anodizingForming a conversion coating on a metal surface by electrolytic oxidation with the metal as the anode; most frequently applied to aluminum.

    antimony(So) A very brittle metal element, neither malleable nor ductile. Its atomic

  • weight is 121.76 and melting point 630.5C.

    Antioch processPlaster molding process using a mixture of about 50% sand, 40% gypsum, and 8% fibrous talc mixed with water in the proportion of 100 parts by weight material with 50 parts water. After air setting, the mold is placed in an autoclave and subjected to 15 psig steam pressure for 6 to 8 hours. The mold is allowed to rehydrate in air for 14 hours and then baked at 450-475F (232-246C) for 25 to 30 hours.

    anti-piping (material)Usually refers to an insulating material placed on top of a sprue or riser, which keeps the metal in liquid or semi-liquid form for a long period of time and minimizes the formation of the usual conical pipe or shrink in the top of a sprue or riser.

    arborA metal barrel, frame or plate to support or carry part of a mold or core.

    argon(AT) An inert gas element with atomic weight of 39.94 and melting point of-189.3C.

    arrester, dustEquipment for removing dust from air.

    as castReferring to a casting which has not received finishing (beyond gate removal or sandblasting), or treatment of any kind including heat treatment after casting. (See: finishing)

    assembling (assembly) lineConveyor system where molds or cores are assembled.

    atmospheric riserA riser that uses atmospheric pressure to aid feeding. Essentially, a "blind riser" into which a small core or rod protrudes. The function of the core or rod is to provide an open passage so the molten interior of the riser will not be under a partial vacuum when metal is withdrawn to feed the casting but will always be under atmospheric pressure.

    atomThe smallest particle of an element.

    austenkicUsual reference is to an alloy steel or iron with structure at room temperature that is normally composed essentially of austenite. A solid solution ofcementite or iron carbide, Fe3C, in iron.

    back draftTaper or draft that prevents removal of pattern from the mold.

    backing board (backing plate)A second bottom board on which molds are opened.

    backing sandThe bulk of the sand in the flask. The sand compacted on top of the facing sand that covers the pattern.

    baffle platePlate or wall in a firebox or furnace to change direction of the flame.

    baked coreA core that has been heated for a sufficient time and temperature to

  • produce the desired physical properties (as opposed to a green-sand core, which is used in the moist state).

    baked permeabilityProperty of a molded mass of sand heated at a temperature above 23 OF (HOC) until dry and cooled to room temperature, to permit passage of gases through it; particularly those generated during pouring of molten metal into a mold.

    baked strengthCompressive, shear, tensile or transverse strength of a molded sand mixture when baked at a temperature above 230F (110C) and then cooled to room temperature.

    band, insideA steel frame placed inside a removable flask to reinforce the sand.

    banking the cupolaMethod of keeping cupola hot and ready for immediate production of hot iron after an unexpected shutdown of several hours. Procedure is to drain all molten iron and slag from the cupola, place extra coke on the top charge and open one or two tuyeres to supply a small natural draft to keep coke combustion going.

    barA rib in the flask to help hold the sand.

    base plateA plate to which the pattern assemblies are attached and to which a flask is subsequently attached to form the mold container.

    basicA chemical term for a material which gives an alkaline reaction.

    basic bottom or lining (furnace)Inner lining and bottom of a melting furnace composed of materials having a basic reaction. Materials may be crushed burnt dolomite, magnesite, magnesite brick or basic slag.

    basic steelSteel melted in a furnace with a basic bottom and lining under a predominantly basic slag.

    basinA cavity on top of the cope into which metal is poured before it enters the sprue.

    batchAmount or quantity of core or mold sand or other material prepared at one time.

    bathMolten metal on the hearth of a furnace, in a crucible or a ladle.

    BaumeDesignating or conforming to either of the scales used by the French chemist Antoine Baume in the gradation of his hydrometers for determining the specific gravity of liquids. There are two scales: one for liquids lighter than water and the other for those heavier than water.

    bauxiteAn ore of aluminum consisting of moderately pure hydrated alumina, Al2O3.2H2O.

    bed chargeThe charge of iron placed on the coke bed in a cupola.

  • bed cokeCoke placed in the cupola well to support the following iron and coke charges.

    bedding a corePlacing an irregularly shaped core on a bed of sand for drying.

    bed-inMethod of ramming the drag mold without rolling it over.

    beehive cokeCoke which is produced in hemispherical ovens about 12 ft in d