Glossary

Abrasion

The displacement and/or detachment of metallic particles from a surface as a consequence of being exposed to flowing solids, fluids or gases.

Abrasion Resistance

Degree of resistance of a material to abrasion or wear.

Acid Embrittlement

Embrittlement during pickling due to absorption of hydrogen.

Age Hardening

Hardening by aging, usually after rapid cooling or cold working.

Aging

A change in properties of metals and alloys which 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 Quenching

Accelerated cooling of alloy in an air stream from temperatures above the Ac3 temperature.

Air Scale

Scale left on ferrous metal in processing, usually from heating in presence of air.

Allowance (Tolerance)

In a foundry, the clearance specified; difference in limiting sizes, as minimum clearance or maximum interference between mating parts, as computed arithmetically.

Alloy

A 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.

Alloy Steel

Steel containing significant quantities of alloying elements other than carbon and the commonly accepted amounts of manganese, silicon, sulfur, and phosphorus.

Alpha - ferrite

Body-centered cubic type of pure iron stable below 1670°F (910°C).

Alpha Martensite

A form or stage of martensite of somewhat arbitrary distinction, probably representing the least developed and most distorted stage in the transformation of austenite to martensite at ordinary temperatures.

Ambient Temperature

Temperature of the surrounding air.

Annealing

Heating to and holding at a suitable temperature, followed by cooling at a suitable rate to lower the hardness or alter other mechanical or physical properties.

Anticarburizing Compounds

Compounds applied to metallic surfaces to prevent surface carbonization.

Argon Oxygen Decarburization (AOD)

A secondary refining process in which argon, oxygen and nitrogen are injected into a molten bath of steel. The AOD process improves metal cleanliness and thus gives superior mechanical properties.

Artificial Aging

An aging treatment above room temperature.

As Cast (as-cast, u.m.)

Referring to metal which has not received finishing (beyond gate removal or sandblasting) or treatment of any kind including heat treatment after casting. Similarly, as drawn, as forged, and as rolled.

ASM

American Society for Metals.

ASNT

American Society for Nondestructive Testing.

ASTM

American Society for Testing and Materials.

Austenite

The face-centered-cubic phase of iron and steel, also referred to as gamma iron. In steel, a solid solution in which gamma iron is the solvent.

Austenite Steel

Any steel containing sufficient alloy to produce a stable austenitic (gamma iron) crystalline structure at ambient temperatures.

Bake

Heat in an oven to a low controlled temperature to remove gases or to harden a binder.

Batch

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

Batch Oven

Oven use to bake a number of cores at one time.

Bead

1) Half-round cavity in a mold, or half-round projection or molding on a casting, 2) a single deposit of weld metal produced by fusion.

BHN

Brinell Hardness Number.

Bimetal

Casting, usually centrifugal, made of two different metals, fused together.

Blacking Carbon

Carbonaceous materials such as plumbago, graphite or powdered coke usually mixed with a binder and frequently carried in suspension in water or other liquid; used as thin facing applied to surfaces of molds or cores to improved casting finish.

Blasting (Blast Cleaning)

A process for cleaning or finishing metal objects by use of an air blast or centrifugal wheel that throws abrasive particles against the surface of the work pieces. Small, irregular particles of steel or iron are used as the abrasive in grit blasting, and steel or iron balls in shot blasting.

Blister

A shallow blow with a thin film of the metal over it appearing on the surface of a casting.

Blow Holes

1) Holes in the head plate or blow plate of a core-blowing machine through which sand is blown from the reservoir into the core box. 2) Irregular shaped cavities with smooth walls produced in a casting when gas is entrapped during mold filling. The gas sources may be air, binder decomposition products or gases dissolved in the molten steel.

Boil

Agitation of a bath of metal caused by the liberation of a gas beneath its surface. May be deliberately induced by the addition of oxidizing material to a bath containing excess carbon. In the later case it is called a carbon boil and CO or CO2 are liberated.

Bond

1) Bonding substance or bonding agents - any material other than water, which, when added to foundry sands, imparts bond strength, 2) the overlapping of brick so as to give both longitudinal and transverse strength.

Bond Strength

Property of a foundry sand to offer resistance to deformation.

Boring

A machining method using single point tools on internal surfaces of revolution.

Boss (Pad)

A projection of circular cross-section on a casting. Usually intended for drilling and tapping for attaching parts.

Bottom Running or Pouring

Filling of the mold cavity from the bottom by means of gates from the runner.

Bright Annealing

A process carried out usually in a controlled furnace atmosphere, so surface does not oxidize, remaining bright.

Brinell Hardness

The value of hardness of a metal on an arbitrary scale representing kg/mm², determined by measuring the diameter of the impression made by a ball of given diameter applied under a known load. Values are expressed in Brinell Hardness Numbers, BHN.

Brittle Fracture

Fracture with little or no plastic deformation. Smoothing machined holes or outside surfaces of castings by drawing, pushing on, or more broaches (special cutting tools) through the roughed out hole.

Bulk Density

The ratio of the weight of a material to its over-all volume (including any inherent porosity).

Burned-On-Sand

A misnomer usually indicating metal penetration into sand resulting in a mixture of sand and metal adhering to the surface of a casting.

Burnishing

Developing a smooth finish on a metal by tumbling or rubbing with a polished hand tool.

CAD

Computer-Aided Design.

CAE

Computer Aided Engineering.

CAM

Computer-Aided Manufacturing.

Carbide

A compound of carbon with one or more metallic elements.

Carbon

Element occurring as diamond and as graphite. Carbon reduces many metals from their oxides when heated with the latter, and small amounts of it greatly affect the properties of iron. Though classed as a nonmetallic, metallurgically, like boron, it is treated as a metal.

Carbonitriding (Nicarbing)

A process in which a ferrous alloy is case hardened by first being heated in a gaseous atmosphere of such composition that the alloy absorbs carbon and nitrogen simultaneously, and then being cooled at a rate that will produce desired properties.

Carburizing

A form of case hardening that produces a carbon gradient inward from the surface, enabling the surface layer to be hardened by either quenching directly from the carbonizing temperature or by cooling to room temperature, then reaustenitizing and quenching.

Case Hardening

A process of hardening a ferrous alloy so that the surface layer or case is made substantially harder than the interior or core. Typically case hardening process are carburizing, carbonitriding, and nitriding.

Cavitation

The formation and collapse of cavities or bubbles within a liquid.

Cementite

A compound of iron and carbon commonly known as iron carbide and having the approximate chemical structure, Fe3C. Cementite is characterized by an orthorhombic crystal structure.

Centrifugal Casting

Casting made in molds which are rotating so as to produce a centrifugal force in the molten metal.

Charpy Impact Test

A pendulum-type single-blow impact test in which the specimen, usually notched, is supported at both ends as a simple beam and broken by a falling pendulum. The energy absorbed in fracture, as impact strength or notch toughness.

Chill (External)

Metal, graphite or carbon blocks that are incorporated into the mold or core to locally increase the rate of heat removal during solidification and reduce shrinkage defects.

Chill (Internal)

A metallic device / insert in molds or cores at the surface of a casting or within the mold to increase the rate of heat removal, include directional solidification and reduce shrinkage defects. The internal chill may then become a part of the casting.

CMM

Coordinate Measuring Machine.

CNC

Computer Numerical Controlled Machine Tools.

Coefficient of Expansion

Unit increase in size resulting from a unit increase in temperature; measured in inches per inch per degree Fahrenheit (in/in/1/2°F) or in millimeter per millimeter per degree Celsius (mm/mm/1/2°C).

Cohesion

The force by which like particles are held together. It varies with different metals and depends upon molecular arrangement due to heat treatment.

Coining

1) A process of straightening and sizing casting by die pressing, 2) a process for shaping metal.

Cold Cracking

Cracks in cold or nearly cold metal due to excessive internal stress caused by contraction. Often brought about when the mold is too hard or casting is of unsuitable design.

Cold Lap

Wrinkled markings on the surface of an ingot or casting from incipient freezing of the surface.

Cold Shot

Small globule of metal embedded in but not entirely fused with the casting.

Cold Shut

Casting defect caused by imperfect fusing or discontinuity of molten metal coming together from opposite directions in a mold, or due to folding of the surface. It may have the appearance of a crack or seam with smooth, rounded edges.

Cold Work

Plastic deformation of a metal at room temperature. Substantial increases in strength and hardness may occur.

Cold-Box Process

1) Any core binder process that uses a gas or vaporized catalyst to cure a coated sand while it is in contact with the core box at room temperature.

Collapsibility

The requirement that a sand mixture break down under the pressure and temperatures developed during casting, in order to avoid hot tears or facilitate the separation of the sand and the casting.

Color Etching

A micro-etch resulting from the formation of a thin film of a definite compound of the metal.

Columnar Structure

A coarse structure of parallel columns of grains, which is caused by highly directional solidification.

Compression Test

Imposing a dead load on a small cylindrical test piece to determine compressive strength, expressed in pounds per sq. in.

Compressive Strength (Yield)

The maximum stress in compression that can be withstood without plastic deformation or failure.

Conduction

The transmission of heat, sound, etc. by the transferring of energy from one particle to another.

Conductivity (Thermal)

The quantity of heat that flows through a material measured in heat units per unit time per unit of cross-sectioned area per unit of length, (electrical) the quantity of electricity that is transferred through a material of know cross-section and length.

Constituent

A micrographically distinguishable part of an alloy or mixture.

Contamination

1) Radioactive deposition of radioactive material in any place where it is not desired, and particularly in any place where its presence may be harmful. The harm may be in vitiating the validity of an experiment or a procedure, or in actually being a source of danger to personnel, 2) presence of small percentages of deleterious elements in an alloy adversely affecting the alloy's mechanical properties and/or casting soundness.

Contraction

The volume change occurring in metals (except antimony and bismuth) and alloys on solidification and cooling to room temperature.

Contraction Cracks

Cracks formed by restriction of the metal while contracting in the mold; may occur just after solidification (called a hot tear) or a short time after the casting has been removed from the mold.

Controlled Atmosphere

Any gas or mixture of gases that prevents or retards oxidation and decarburization.

Convection

The motion resulting in a fluid from the differences in density. In heat transmission, this meaning has been extended to include both forced and natural motion or circulation.

Converter

A furnace in which a gas, usually air, is blown through the molten bath or crude metal for the purpose of oxidizing impurities.

Conveyor, Vibratory

A materials-handling device used usually with shakeout operations, to help clean sand from the castings as they are moved from one place to another in the foundry and as a feeding device to regulate materials flow. Operations with vibrational energy.

Cooling Curve

A curve showing the relationship between time and temperature during the solidification and cooling of a metal sample. Since most phase changes involve evolution or absorption of heat, there may be abrupt changes in the slope of the curve.

Cooling, Controlled

A process of cooling from an elevated temperature in a predetermined manner used to produce a desired microstructure to avoid hardening, cracking or internal damage.

Cope

Upper or topmost section of a flask, mold or pattern.

Core

A performed sand aggregate inserted in a mold to shape the interior or that part of a casting which cannot be shaped by the pattern.

Core Binder

Any material used to hold the grains of core sand together.

Core Blow

A gas pocket in a casting adjacent to a core cavity caused by entrapping gases from the core.

Core Box, Combination

Core box and core dryers from the same pattern. One half is used as a half core box and a core drier.

Core Compound

A commercial mixture used as a binder in core sand.

Core Density

1) Permeability of core or 2) weight per unit volume.

Core Hardness

The ability of a core to resist scratching or abrasion.

Core Sand

Sand for making cores to which a binding material has been added to obtain good cohesion and permeability after drying. Usually low in clays.

Core Shift

A variation from specified dimensions of a cored section due to a change in position of the core or misalignment of cores in assembling.

Core Vents

1) holes made in the core for escape of gas. 2) A metal screen or slotted piece used to form the vent passage in the core box employed in a core-blowing machine. 3) A wax product, round or oval in form, used to form the vent passage in a core.

Coring (Metallurgical)

Variable composition due to the solidification characteristics of an alloy. Typically these compositional differences occur on a micro scale, the distances between compositional extremes being controlled by the solidification structure of the alloy.

Corrosion

1) Gradual chemical or electrochemical attack on a metal by atmosphere, moisture or other agents, 2) chemical attack of furnace linings by gases, slags, ashes or other fluxes occurring in various melting practices.

Corrosion Index

A number expressing the maximum depth in mils to which corrosion would penetrate in one year on the basis of a linear extrapolation of the penetration occurring during the lifetime of a given test or service.

Corrosion Wear

Wear in which chemical or electrochemical reaction with the environment is significant.

Cover

A protective blanket laid on a melt to exclude oxidizing atmosphere and in the case of magnesium to prevent its igniting. Neutral covers simply protect metal from atmosphere; reacting covers contain an agent such as a deoxidizer.

Cover Core

A core set in place during the ramming of a mold to cover and complete a cavity partly formed by the withdrawal of a loose part of the pattern. Also used to form part or all of the cope surface of the mold cavity. A core placed over another core to create a flat parting line.

Crack, Hot Tear

A rupture occurring in a casting at or just below the solidifying temperature by a pulling apart of the soft metal, caused by thermal contraction stresses.

Cracking Strip

A fin of metal molded on the surface of a casting to prevent cracking.

Creep

The flow or plastic deformation of metals held for long periods of time at stresses lower than the normal yield strength. The effect is particularly important if the temperature of stressing is in the vicinity of the recrystallization temperature of the metal.

Creep Limit

The maximum stress that will result in creep at a rate lower than an assigned rate.

Critical Cooling Rate

The minimum rate of continuous cooling just enough to prevent undesired transformations.

Cross Section

A view of the interior of an object that is represented as being cut in two, the cut surface presenting the cross section of the object.

Crucible

A ceramic pot or receptacle made of materials such as graphite or silicon carbide, with relatively high thermal conductivity, bonded with clay or carbon, and used in melting metals; sometimes applied to pots made of cast iron, steel, or wrought steel.

Crucible Furnace

A furnace fired with coke, oil, gas, or electricity in which metals are melted in a refractory crucible.

Crystal

A physically homogeneous solid in which the atoms, ions, or molecules are arranged in a three-dimensional repetitive pattern.

Crystal Lattice

The way atoms are arranged in a crystal. Spacewise, there are only 14 different lattices.

Crystalline Fracture

Fracture of a brittle metal, showing definite crystal faces in the fractured surface.

Curing Time (No Bake)

That period of time needed before a sand mass reaches maximum hardness.

Cutoff Machine, Abrasive

A device using a thin abrasive wheel rotating at high speed to cut off gates and risers from castings, or in similar operations.

Datum Points

In layout and machining operations the reference points on a datum plane from which dimensions are measured.

Decant

1) Pour from one vessel to another, 2) pour off molten metal without disturbing the sludge.

Decarburization

Loss of carbon from the surface of a ferrous alloy as a result of heating in a medium, usually oxygen, that reacts with carbon.

Deep Etching

Macroetching; etching for examination at a low (less than 10X) magnification, in a reagent that attacks the metal to a much greater extent than normal for microscopic examination. Gross features may be developed; i.e., abnormal grain size, segregation, cracks, or grain flow.

Defect

A discontinuity in the product whose severity is judged unacceptable in accordance with the applicable product specification.

Deformation Test

An AGS test using an instrument, such as the Dietert Universal Sand-Strength Testing machine (with deformation accessory), to determine the amount in inches that the sand specimen is compressed before it ruptures.

Degasser

A material employed for removing gases from molten metals and alloys.

Degassing

Usually a chemical reaction resulting from a compound added to molten metal to remove gases from the metal. Often inert gases are used in this operation.

Degassing Flux

A flux for removing gas from the melt.

Dendrite

A crystal of branched appearance, formed during solidification of alloys, the branching habit being controlled by specific crystallographic directions.

Density

The mass per unit volume of a substance, usually expressed in grams per cubic centimeter or in pounds per cubic foot.

Deoxidation

Removal of excess oxygen from molten metal, usually accomplished by adding materials with a high affinity for oxygen, the oxides of which are either gaseous or readily form slags.

Dephosphorization

Elimination of phosphorus from molten steel.

Descale

Remove the fire scale from the surface of casting.

Desulfurization

Removal of sulfur from the molten metal by addition of suitable compounds.

Dewaxing

The process of melting out the expendable wax pattern from an investment mold by the application of heat, usually at temperatures less than 250°F (121)°C).

Diameters

In microscopy, an indication of the amount of magnification. 1000 diameters=1000 times original size.

Die

A metal block used in forming materials by casting, molding, stamping, threading, or extruding.

Die Assembly

The parts of a die stamp or press that hold the die and locate it for the punches.

Die Casting (Brit. Pressure Die Casting)

A rapid, water-cooled permanent mold casting process limited to nonferrous metals. There are three types: the plunger-type operated hydraulically, mechanically, or by compressed air with or without a gooseneck; the direct-air injection which forces metal from a goose-neck into the die, and the Cold-Chamber Machine. All force the metal into the die with a pressure greater than that of gravity flow.

Differential Heat Treatment

A heating process by which the temperature is varied within the object so that, after cooling, various parts may have different properties as desired.

Diffuser

X-ray equipment, a portion of the condensing and focusing system that permits even distribution of energy.

Dimensional Tolerance Grades

A system of classifying the tightness of tolerances for the purpose of defining accurately the tolerances involved, and for simplifying the communication process between customer and producer regarding what is wanted, and what is possible, respectively.

Dip Coat

In solid and shell mold investment casting, a fine ceramic coating applied as a slurry to the pattern to produce maximum surface smoothness, followed by a cheaper conventional investment.

Direct Casting

Teeming from the ladle into the casting mold without the use of a tundish.

Direct-Arc Furnace

An electric arc furnace in which the metal being melted is one of the poles.

Dispersed Shrinkage

Small shrinkage cavities dispersed through the casting, which are not necessarily cause for rejection.

Disruptive Strength

Maximum strength of a metal when subjected to three principal tensile stresses at right angles to one another and of equal magnitude.

Dissolved Carbon

Carbon in solution in steel in either the liquid or solid state.

Double Annealing

As applied to hypoeutectoid steel, a process of heating to above the upper critical point (AC3) and holding at that temperature until complete solution of the carbide has been achieved then cooling rapidly and reheating immediately to above A3 and slowly cooling.

Double Tempering

A retempering operation sometimes necessary for steel containing retained austenite which breaks down during cooling from the first tempering to form a new, and hence, untempered martensite.

Drag

Lower or bottom section of a mold or pattern.

Draw

A term used for 1) to temper, 2) to remove pattern from mold, 3) an external contraction defect on surface of mold.

Drier (Dryer)

A material, as alcohol ammonium nitrate, sodium perborate and manganese oleate, added to a core or mold mixture to remove or reduce the water content.

Dry Sand Casting

The process in which the sand molds are dried at above 212°F (100°C) before using.

Dry Sand Mold

A mold from which the moisture has been removed by heating.

Dry Strength, or Dry Bond Strength

The maximum compressive, shear, tensile, or transverse strength of a sand mixture which has been dried at 220 to 230°F (105 to 110°C) and cooled to room temperature.

Dual Metal Centrifugal Casting

Centrifugal castings produced by pouring a different metal into the rotating mold after the first metal poured.

Eddy Current Testing

The detection of discontinuities by observation of the interaction between electromagnetic fields and metals.

Elastic Limit

Maximum stress that a material will withstand without permanent deformation.

Elasticity

The property of recovering original shape and dimensions upon removal of a deforming force.

Electrode

Compressed graphite or carbon cylinder or rod used to conduct electric current in electric arc furnaces, arc lamps, carbon arc welding, etc.

Elongation

Amount of permanent extension in the vicinity of the fractures in the tensile test; usually expressed as percentage of original gage length.

Embrittlement

Loss of ductility of a metal due to chemical or physical change.

End-Quench Hardenability Test

A standardized method for comparing the hardenability of different steels.

Endothermic Reaction

The reaction which occurs with absorption of heat.

Engineering Strain (e)

The average linear strain, obtained by dividing the elongation of the length of the specimen by the original gage length.

Engineering Stress (s)

The load divided by the original area.

Equilibrium

A dynamic condition of balance between atomic movements, where the resultant is zero and the condition appears to be one of rest rather than change.

Eutectic

1) An isothermal reversible reaction in which a liquid solution decomposes, on cooling, into two or more intimately mixed solids. The number of solids formed are the same number of components in the system. 2) An alloy having the chemical composition indicated by the eutectic point on an equilibrium diagram.

Eutectoid

1) An isothermal reversible reaction in which a solid solution on cooling is converted into two or more intimately mixed solids. The number of solids formed are the same number of components in the system. 2) An alloy having the same chemical composition indicated by the eutectoid point on an equilibrium diagram.

Exothermic

Formed by or characterized by heat reaction as in oxidation.

Fabrication

The joining, usually by welding, of two or more parts to produce a finished assembly. The components of the assembly may be a combination of cast and wrought materials.

Facing Sand

Specially prepared molding sand mixture used in the mold adjacent to the pattern to produce a smooth casting surface.

Fatigue

The loss of load-bearing ability of a material under repeated load application, as opposed to a single load.

Fatigue Crack or Failure

A fracture starting from a nucleus where there is an abnormal concentration of cyclic stress. The fracture surface is smooth and frequently shows concentric (sea shell) markings with a nucleus as a center.

Fatigue Limit (Endurance Limit)

Maximum stress that a material will endure without failure for an infinite number of load cycles.

Fatigue Strength

Maximum stress that a material will endure without failure for a specified number of load cycles.

Feeding

The process of supplying molten metal to compensate for volume shrinkage while the casting is solidifying.

Ferrite

A solid solution of one or more elements in the body-center-cubic phase of iron or steel.

Ferritic Steels

Steels in which ferrite is the predominant phase. These steels are magnetic.

Fillet

A concave corner piece used on foundry patterns, a radius joint replacing sharp inside corners.

Finish Allowance

The amount of stock left on the surface of a casting for machining.

Finish Welding

Production welding carried out in order to ensure the agreed quality of the casting.

Finite Element Analysis (FEA)

A computerized numerical analysis technique used for solving differential equations to primarily solve mechanical engineering problems relating to stress analysis.

Flash

A thin section of metal formed at the mold, core, or die joint or parting in a casting due to the cope and drag not matching completely, or where core and coreprint do not match.

Flask

A metal frame used for making or holding a sand mold. The upper part is the cope and the bottom half is the drag.

Fluidity

The ability of molten metal to flow. Common devices used to measure fluidity are: spiral casting and the Chinese Puzzle.

Fluidize

To impart fluid like properties to powders or sands e.g. fluidized beds.

Foundry Returns

Metal in the form of sprues, gates, runners, risers and scrapped castings, with known chemical composition that are returned to the furnace for remelting. Sometimes referred to as "revert".

Frictional Wear

The displacement and/or detachment of metallic particles from a surface as a consequence of being in contact with another moving component.

Gate

The end of a runner in a mold where molten metal enters the mold cavity.

Gating System

The complete assembly of sprues, runners and gates in a mold through which steel flows before entering the casting cavity.

Granular Fracture (Crystalline Fracture)

A type of irregular surface produced when metal is broken.

Green Sand

A naturally bonded sand, or a compounded molding sand mixture which has been tempered with water for use while still in the damp or wet condition.

Green Sand Core

A sand core used in the unbaked condition, also a core made from green sand and used as rammed.

Hardenability

In a ferrous alloy, the property that determines the depth and distribution of hardness induced by quenching.

Hardness

Resistance of a material to indentation as measured by such methods as Brinell, Rockwell, and Vickers. The term hardness also refers to stiffness of a material, or its resistance to scratching, abrasion, or cutting.

Heat

The total amount of metal produced which can be represented by one analysis sample and one set of mechanical tests.

Heat Treatment

A combination of heating and cooling operations applied to a metal or alloy to produce desired properties and microstructures.

High-Alloy Steel

Ferrous alloy with more than 12 weight percent of noncarbon additions.

Hollow Drill Test (Trepanning)

Removing a cylindrical sample from a metal section or structure to determine soundness of the section.

Homogenizing

A process of heat treatment at high temperature intended to eliminate or decrease chemical segregation by diffusion.

Horizontal Axis Casting Machine

A centrifugal casting machine in which the axis of rotation of the mold is horizontal.

Hot Tear

A crack or fracture formed prior to completion of metal solidification as a result of hindered contraction. A hot tear is frequently open to the surface of the casting and is commonly associated with design limitations.

Hydrogen Embrittlement

A condition of low ductility resulting from the absorption of hydrogen. A time dependent fracture process which results in a loss of ductility.

ICI

Investment Casting Institute

ID Grinding

Term for internal (dimension) grinding.

Impact Strength

The resistance to impact loads; usually expressed as the foot pounds of energy absorbed in breaking a standard specimen.

Impact Value

Total energy needed to break a standard specimen by a single blow under standard conditions; e.g., Charpy Impact Test.

Impregnation

The treatment of castings with a sealing medium to stop pressure leaks, such as soaking under pressure with or without prior evacuation, and either with hot or cold application. Mediums used include silicate of soda, drying oils with or without styrene, plastics, and proprietary compounds.

Impurity

An element unintentionally allowed in a metal or alloy. Some impurities have little effect on properties; others will grossly damage the alloy.

Inclusions

Nonmetallic materials in a metal matrix. Sources include reoxidation, refractories, slag, and deoxidization products.

Indentation Hardness

The resistance of a material to indentation. This is the usual type of hardness test, in which a pointed or rounded indenter is pressed into a surface under a substantially static load.

Indirect-Arc Furnace

An AC (Alternating Current) electric-arc furnace in which the metal is not one of the poles.

Induction Furnace

An AC melting furnace which utilizes the heat of electrical induction.

Induction Hardening

A surface hardening process involving the localized use of pulsating magnetic currents to achieve heating above the austenite transformation temperature, Ac3, followed by quenching.

Induction Heating

Process of heating by electrical resistance and hysteresis losses induced by subjecting a metal to the varying magnetic field surrounding a coil carrying an alternating current.

Inert Gas

A gas that will not support combustion or sustain any chemical reaction; e.g., argon or helium.

Ingot

A mass of metal cast to a convenient size and shape for remelting or hot working.

Insert

A part usually formed from metal, which is placed in a mold and may become an integral part of the casting.

Insulating Pads and Sleeves

As opposed to chills, insulating material, such as gypsum, diatomaceous earth, etc., used to lower the rate of solidification. As sleeves on open risers, they are used to keep the metal liquid, thus increasing the feed efficiency.

Intergranular Corrosion

Corrosion in a metal taking place preferentially along the grain boundaries.

Internal Shrinkage

A void or network of voids within a casting caused by inadequate feeding of that section during solidification.

Internal Stresses (or Thermal Stresses)

Generally stresses which occur during the cooling of a part.

Interrupted Quench

Removing the casting from a quenching bath before it has reached the temperature of the bath.

Investment Casting

Casting produced in a mold obtained by investing an expendable pattern with a refractory to produce a shell. The expendable pattern may consist of wax, plastic, or other material and is removed prior to filling the mold with liquid metal.

Iron

1) A metallic element, mp 1535°C (2795°F), 2) irons not falling into the steel categories, as Gray Iron, Ductile Iron, Malleable Iron, White Iron, Ingot, and Wrought Iron.

Iron, Malleable

A mixture of iron and carbon, including smaller amounts of silicon, manganese, phosphorus, and sulfur, which after being cast (white iron, carbon in combined form as carbides) is converted structurally by heat treatment into a matrix of ferrite containing nodules of temper carbon (graphite).

ISO

International Standards Organization

Isocure

Proprietary name for a binder system developed for use in Ashland (Cold Box) Process, itself a proprietary process.

Isothermal

Pertaining to changes or other phenomena occurring at a constant temperature.

Isothermal Annealing

A process in which a ferrous alloy is heated to produce a structure partly or wholly austenitic, and is then cooled to and held at a temperature that causes transformation of the Austenite to a relatively soft ferric-carbide aggregate.

Isothermal Transformation

1) The process of transforming Austenite in a ferrous ally to Ferrite or a ferrite-carbide aggregate at any constant temperature within the transformation range, 2) transformation of one phase in an alloy system to another phase at any constant temperature.

Jobbing Foundry

A foundry engaged in the manufacture of numerous types of castings.

Joint Welding

Production welding used to weld cast components together to obtain an integral unit.

K Factor

Tensile strength in pounds per square inch divided by the Brinell Hardness number.

Kayser Hardness Test

A method for determining the true hardness of metals at high temperatures.

Kerf

The width of a cut.

Keyhole Specimen

A type of notched impact test specimen which has a hole-and-slot notch shaped like a keyhole.

Knockout Pins (Ejector Pins)

Small diameter pins affixed to a pattern back-up plate for removing cured mold in the shell-molding process.

Ladle

Metal receptacle frequently lined with refractories used for transporting and pouring molten metal. Types include hand bull, crane, bottom-pour, holding, teapot, shank, lip-pour.

Ladle, Bottom-Pour

Ladle from which metal flows through a nozzle in the bottom.

Ladle, Lip-Pour

Ladle in which the metal is poured over a lip.

Ladle, Teapot

A ladle in which, by means of an external spout, metal is removed from the bottom rather than the top of the ladle.

Lateral Expansion

A measured property used in Charpy Impact Testing. Refers to the increase width of the specimen after fracture.

Lining

Inside refractory layer of firebrick, clay, sand, or other material in a furnace or ladle.

Liquid Penetrant Testing

A nondestructive testing method suitable for evaluating the surface integrity of non-magnetic and ferro-magnetic parts.

Machine Allowance

Stock added to the part to permit machining of the part to final dimensions.

Magnetic Particle Inspection

A nondestructive method of inspecting the surface integrity of ferromagnetic materials.

Martempering (Interrupted Quenching)

A hardening treatment of a steel involving a slow cool through the martensitic transformation range to reduce stresses associated with the quenching of austenite. An important aspect of martempering is that no transformation product other than martensite should form.

Martensite

A generic term used for microstructures formed by diffusionless phase transformations. A constituent found in hardened steel; has a needle like microstructure.

Martensitic Stainless Steels

A corrosion-resistant ferrous alloy with a predominant martensitic phase.

Mass Effect

The effect that the mass of a component has on the properties of the material from which the part is made. In castings such effects may arise due to the effect of mass on the solidification and on the rate of temperature change heat treatment.

Mechanical Properties

Properties of a material that reveal its strength and elastic behavior.

Metallographic Structure

The nature, distribution, and amounts of the metallographic constituents in a metal.

Metalloid

1) An element intermediate between metals and nonmetals possessing both metallic and nonmetallic properties, as arsenic, 2) sometimes applied to elements commonly bonded in small amounts in steel, as carbon, manganese, boron, silicon, sulfur, and phosphorus.

Metallurgical Bond

The bond between two metals whose interface is free of voids, oxide films, or discontinuities.

Metallurgy

The science and technology of metals, a broad field that includes, but is not limited to, the study of internal structures and properties of metals and the effects on them of various processing methods.

Metalock

A method of cold repair of castings and forgings.

Metals Comparator

An instrument for testing or identifying metallic and nonmetallic parts. Parts are placed in an electromagnetic field and a standard parts in a matched electromagnetic field. Distortions of the magnetic fields are compared on an oscilloscope.

Meyer Hardness Test

A test to determine tendency of a metal to harden when deformed plastically. A series of indentations are made in the metal using a fixed-diameter ball and progressively increasing loads.

Mf

The temperature at which martensite formation finishes during cooling.

Microetching

Etching of metal samples for examination under the microscope.

Microformer

A type of extensometer for measuring elongation of test piece in a tensile test.

Micrography

Examination by means of a microscope.

Microhardness

The hardness of microconstituents of a material.

Microradiography

The process of passing x-rays through a thin section of an alloy in contact with a photographic emulsion, and then magnifying the radiograph 50 to 100 times to observe the distribution of alloying constituents and voids.

Microscopic

Minute object or structures which are invisible, or not clearly distinguished, without the use of a microscope.

Microsection

A metal specimen whose surface has been polished and etched to reveal the microstructure.

Microshrinkage

Very finely divided porosity resulting from interdendritic shrinkage, resolved only by use of the microscope; may be visible on radiographic films as mottling. Etching shows they occur at intersections of convergent dendritic directions.

Microspectroscopy

A method of identifying metallic constituents using spectrographic arc.

Microstructure

The structure of polished and etched metal and alloy specimens, as revealed by the microscope at magnifications over 10 diameters.

MIL STD

United States Government military standards, specifications, usually requiring rugged, exacting testing, equal to the exigencies of combat usage.

Mild Steel

Plain carbon steel of about 0.25% carbon or less.

Mill Scale

Iron oxide scale formed on steel during hot working processes, cooled in air.

Milling

Removing metal with a milling cutter.

Mock-Up

A full-size model built accurately for study, testing or display.

Model

A proportional representation of an object in any scale.

Modell Number

A value giving a measure of wear resistance.

Modulus of Elasticity (E)

In tension it is the ration of stress to the corresponding strain, within the limit of elasticity (Yield Point) of a material. For carbon and low alloy steels, any composition and treatment, the value is approximately 30,000,000 psi.

Modulus of Resilience (ur)

The amount of strain energy per unit volume required to stress a material from zero to the yield stress limit. The modulus of resilience is proportional to the area under the elastic portion of the stress-strain diagram. Units are Pa or psi.

Modulus of Rigidity

In a torsion test, the ratio of the unit shear stress to the displacement caused by it per unit length in the elastic range. (See Shear Moduls).

Modulus of Rupture

Used in both bending and torsion testing. In bending, the modulus of rupture is the bending moment at fracture, divided by the section modulus. In torsion, modulus of rupture is the torque at fracture divided by the polar section modulus.

Modulus of Toughness (ut)

Amount of work per unit volume of a material, required to carry that material to failure under static loading. Equal to the area under the entire stress-strain curve. Units are Pa or psi.

Moh's Scale

A scratch hardness test for determining comparative harness, using ten standard minerals from talc to diamond.

Mold Cavity

The space in a mold which is filled with liquid metal to form the casting upon solidification. The channels through which liquid metal enters the mold cavity (sprue, runner, gates) and reservoirs for liquid metal (risers), are not considered part of the mold cavity proper.

Mold Coating (Mold Facing, Dressing)

1) Coating to prevent surface defects on permanent mold castings and die castings, 2) coating on sand molds to prevent metal penetration and improve metal finish.

Mold Cover Half (Cover Die)

1) The top half of the mold, the cope, 2) in die casting, the front half of the die, which remains stationary as the die is opened.

Mold Shift

A casting discontinuity resulting from misalignment of the cope and drag halves.

Moldability

Ability of sand to flow into a flask and around a pattern; measured in the amount of sand falling through an inclined screen or slot.

Molding Material

A material suitable for making molds into which molten metal can be cast.

Molding Sands

Sands containing over 5% natural clay (usually between 8 and 20%).

Molding, Floor

Making sand molds from loose or production patterns of such size that they cannot be satisfactorily handled on a bench or molding machine; the equipment being located on the floor during the entire operation of making the mold.

Molding, Pit

Molding method in which the drag is made in a pit or hole in the floor.

Mushy Stage

The state between solid and liquid in alloys, which freeze over a wide range of temperatures.

NACE

National Association of Corrosion Engineers.

NBS

National Bureau of Standards. Changed to NIST in 1988.

Necking

Reducing the cross sectional area of the metal in an area by stretching.

Needles

Elongated acicular crystals tapering at each end to a fine point as martensite.

Negative Quenching (Negative Hardening)

Accelerated cooling in water or oil from a temperature below the critical range.

NFFS

Non-Ferrous Founder's Society.

Nimonic

Class of nickel-base cast alloy resistant to stress and to oxidation at high temperatures.

NISA

National Industrial Sand Association.

NIST

National Institute of Standards and Technology. Formerly NBS (National Bureau of Standards)

Nital

A solution of nitric acid in alcohol use as an etching agent in ferrous metallography.

Nitriding

A surface hardening process involving heating in an atmosphere of ammonia, or in contact with a nitrogen-bearing material, so as to promote the absorption of nitrogen.

Nitrogen Flush

Bubbling nitrogen gas through a metal melt under vacuum (as with valve bronze), to improve tensile properties and pressure tightness.

Nobake Binder

A synthetic liquid resin sand binder that hardens completely at room temperature, generally not requiring baking, used in Cold-Setting process.

Nodular Iron

Iron of a normally gray cast iron type that has been suitably treated with a nodularizing agent so that all, or the major portion of its graphitic carbon, has a nodular or spherulitic form as cast. Often referred to as Ductile Iron.

Nondestructive Testing (Inspection)

Testing or inspection that does not destroy the object being tested or inspected.

Nonferrous

A negative term; refers to alloy in which the predominate metal or solvent is not iron.

Normal Segregation

Concentration of alloying constituents that have low melting points in those portions of a casting that solidify last.

Normalizing

Heating a ferrous alloy to a suitable temperature above the transformation temperature Ac3, followed by cooling at a suitable rate, usually in still air to a temperature substantially below the transformation range.

Nucleation

1) (homogeneous) the initiation of solid crystals from the liquid stage, or initiation of solid crystals from the liquid stage, or a new phase within a solid, without outside interference - rarely occurs, 2) (heterogeneous) foreign particles altering the liquid-solid interface energy during phase changes.

Oil Quenching

Quenching in oil.

Open Grain Structure

A defect wherein a casting, when machined or fractured, appears to be coarse grained and porous; usually due to a shrink area.

Optimum Moisture

That moisture content which results in developing the maximum of any property of a sand mixture.

Orange Peel

A pebble-grained surface that develops in the mechanical forming of sheet metals with coarse grains.

Oven, Drying

A furnace or oven for drying molds or cores.

Overaging

Aging a precipitation-hardening alloy under conditions of time and temperature greater than those required to obtain maximum strength or hardness

Overheated

A term applied when, after exposure to an excessively high temperature, a metal develops an undesirable coarse grain structure, but is not necessarily damaged permanently. Unlike burned structure, the structure produced by overheating can be corrected by suitable heat treatment, by mechanical work, or by a combination of the two.

Overstressing

Permanently deforming a metal by subjecting it to stresses that exceed the elastic limit.

Oxidation

Any reaction of an element with oxygen. In a narrow sense, oxidation means the taking on of oxygen by an element or compound, and on the basis of the electron theory, it is a process in which an element loses electrons.

Oxide

A compound of oxygen with another element.

Oxidizing Atmosphere

An atmosphere resulting from the combustion of fuels in an atmosphere where excess oxygen is present, and with no unburned fuel lost in the products of combustion.

Packing or Packing Material

Sand, gravel, mill scale or similar materials used to support castings packed in annealing pots to prevent possible warpage under high temperatures.

Padding

The process of adding metal to a cross section of a casting wall, usually extending from a riser, to ensure adequate feed to a localized area where a shrink would occur if the added metal were not present.

Parted Pattern

A pattern made in two or more parts.

Parting Line

A line on a pattern or casting corresponding to the separation between the cope and drag portions of a sand mold.

Passivity

The property of some metals to become abnormally inactive towards certain reagents.

Pattern

A form of wood, plastic, metal, or other material around which molding material is placed to make a mold.

Pattern Draft

The taper on vertical elements in a pattern which allows easy separation of pattern from compacted sand mixture.

Pattern Layout

Full-sized drawing of a pattern showing its arrangement and structure features.

Patternmaker

A craftsman engaged in production of foundry patterns from wood, plastic, or metals, such as aluminum, brass, etc.

Perlite

A highly siliceous volcanic rock which can be expended by heating into a porous mass of particles. Perlite can be used as an insulation in foundry sand mixtures. Not to be confused with Pearlite.

Permanent Mold

A metal mold of two or more parts; not an ingot mold. It is used repeatedly for the production of many castings of the same form.

Phase Diagram

A graphic representation of the equilibrium temperature and composition limits of phase fields reactions in an alloy system. In a binary system, temperature is usually the ordinate and composition the abscissa. Ternary and more complex systems require several two-dimensional diagrams to show the temperature - composition variables completely. In alloy systems, pressure is usually considered constant, although it may be treated as an additional variable.

Photomicrograph

A photograph of the grain structure of a metal as observed when optically magnified more than 10 diameters. The term micrograph may be used.

Physical Metallurgy

The science concerned with the physical and mechanical characteristics of metals and alloys.

Pitting

A form of wear characterized by the presence of surface cavities, the formation of which is attributed to processes such as fatigue, local adhesion, cavitation or corrosion.

Plane Strain

A 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. Under plane strain conditions, the plane of fracture instability is normal to the axis of the principal tensile stress.

Plastic Deformation

Permanent distortion of a material under the action of applied pressure.

Postheating

A process used immediately after welding whereby heat is applied to the weld zone, either for tempering, or for providing a controlled rate of cooling, in order to avoid a hard or brittle structure.

Pouring

Transfer of molten metal from furnace to ladle, ladle to ladle, or ladle into molds.

Pouring Cup

The flared section of the top of the downsprue. It can be shaped by hand in the cope, or be a shaped part of the pattern used to form the downsprue; also may be baked core cup placed on the top of the cope, over the downsprue.

Precipitation Hardening

A process of hardening an alloy in which a constituent precipitates from a supersaturated solid solution.

Precipitation Heat Treatment

Any of the various aging treatments conducted at elevated temperatures to improve certain mechanical properties through precipitation from solid solution.

Preheating

A general term for heating material, as a die in die casting, as a preliminary to operation, to reduce thermal shock and prevent adherence of molten metal.

Primary Choke (Choke)

That part of the gating system which most restricts or regulates the flow of metal into the mold cavity.

Process Capability

The amount of variation in the output of a controlled manufacturing process, the range defined by plus or minus three standard deviations.

Proeutectoid

The constituent that separates out of a solid solution before the formation of eutectoid.

Profile Tolerances

A system of locating and tolerancing developed to control the orientation of rough parts in machine fixtures. From locating points on the casting a "perfect profile" is established for all surfaces and features. A tolerance envelope surrounding that profile defines the limitations of an acceptable part.

PSI

Pounds per square inch.

Quenching

Rapid cooling or hardening; normally achieved by immersion of the object to be hardened in water, oil, or solutions of salt or organic compounds in water.

Radiant Heat

Heat communicated by radiation and transmitted by electromagnetic waves.

Radioactive Isotopes

Varieties of an element possessing the same chemical characteristics, but emitting detectable radiations, by means of which they can be identified and traced.

Radioactive Material

Any compound or element which may emit any or all of the following; alpha and beta particles, electrons, photons neutrons and gamma, and all other emissions which produce ionization directly or indirectly.

Ramming

Packing sand in a mold by raising and dropping the sand pattern flask on a table. Jolt squeezers, jarring machines, and jolt rammers are machines using this principle.

Range

The difference between the highest and lowest values of a measurable attribute of the output of a process.

Recrystallization

A process whereby the distorted grain structure of cold-worked metals is replaced by a new, strain-free grain structure, during annealing above a specific minimum temperature.

Recrystallization Temperature

The lowest temperature at which the distorted grain structure of a cold-worked metal is replaced by a new, strain-free grain structure, during prolonged annealing. Time, purity of the metal, and prior deformation are important factors.

Reduction

The removal of oxygen or addition of hydrogen.

Refractory

1) Heat-resistant material, usually non-metallic, used for furnace linings etc., 2) the quality of resisting heat.

Repair Welding

Any welding carried out after delivery to the end user, e.g., after the casting has been in service.

Revert

Recycled sprues, gates, risers, defective castings and machine chips.

Rigging

Gates, risers, loose pieces, etc., needed on the pattern to produce a sound casting.

Riser

Reservoir of molten metal from which casting feeds as it shrinks during solidification.

Riser Height

The distance from the top of the riser when liquid rises to the top of the riser neck. Riser height when solid is usually several inches less than when liquid because of contraction and loss of feed metal to the casting.

Riser, Blind

A riser that does not break through the top of the cope, and is entirely surrounded by sand; opened to the atmosphere by means of a firecracker core.

Riser, Open

Conventional form of riser usually located at the heaviest section of the casting, and extending through the entire height of the cope.

Riser-Gating

Practice of running metal for the casting through the riser to help directional solidification.

Runner

A channel through which molten metal or slag is passed from one receptacle to another; in a mold, the portion of the gate assembly that connects the downgate, or sprue, with the casting ingate or riser. The term also applies to similar portions of master patterns, pattern dies, patterns, investment molds, and finished castings.

Runner Extension

In a mold, that part of a runner which extends beyond the farthest ingate as a blind end. It acts as a dirt trap since the first rush of metal along the runner will pick up any loose particles of sand or dirt, and carry them into the extension (not into the mold cavity).

Runner Riser

A conventional runner, usually in the horizontal plane, which permits flow of molten metal to the ingate, and is large enough to act as a reservoir to feed the casting.

Runout

A casting defect caused by incomplete filling of the mold due to molten metal draining or leaking out of some part of the mold cavity during pouring; escape of molten metal from a furnace, mold, or melting crucible.

Sag

A decrease in metal section in casting due to sagging of the cope or core.

Sand

In metalcasting, a loose, granular material high in SiO2, resulting from the disintegration of rock. The name sand refers to the size of grain, and not to mineral composition. Diameter of the individual grains can vary from approximately 6, to 270 mesh. Most foundry sands are made up principally of the mineral quartz (silica). Reason for this is that sand is plentiful, refractory, and cheap; miscellaneous sands include zircon, olivine, chromite, CaCO3, black sand (lava grains), titanium minerals, and others.

Sand Casting

Metal castings produced in sand molds.

Sand Control

Procedure whereby various properties of foundry sand, such as fineness, permeability, green strength, moisture content, etc., are adjusted to obtain castings free from blows, scabs, veins, and similar defects.

Sand Porosity

Volume of the pore spaces or folds in a sand. (Not synonymous with permeability).

Sand Reclamation

Processing of used foundry sand grains by thermal, attraction or hydraulic methods, so that it may be used in place of new sand without substantially changing current foundry sand practice.

Scaling (Scale)

Surface oxidation, partially adherent layers of corrosion products, left on metals by heating or casting in air or in other oxidizing atmospheres.

Scanning Electron Microscope (SEM)

An instrument used for obtaining microstructure images, using an electron beam. The micrographs obtained give depth perception of the metal being observed.

Scrap (Metal)

Metal to be remelted; includes scrapped machinery fabricated items such as rail or structural steel and rejected castings.

Seam

A surface defect on a casting related to but of lesser degree than a Cold Shut; a ridge on the surface of a casting caused by a crack in the mold face.

Segregation

A concentration of alloying elements at specific regions, usually as a result of the primary crystallization of one phase with the subsequent concentration of other elements in the remaining liquid.

SFSA

Steel Founders' Society.

Shakeout

1) The operation of removing castings from the mold 2) a mechanical unit for separating the molding materials from the solidified metal casting.

Shear

A type of deformation in which parallel planes in the metal crystals slide so as to retain their parallel relation.

Shear Modulus (G)

In a torsion test, the ratio of the unit shear stress to the displacement caused by its per unit length in the elastic range. Units are Pa or psi.

Shear Strain

Elastic displacement produced by pure shear loading.

Shear Strength

Maximum shear stress a material is capable of withstanding without failure.

Shear Stress

Load per unit area parallel to the plane of contact.

Shell Molding

A process for forming a mold from resin-bonded sand mixtures brought in contact with pre-heated (300-500°F) metal patterns, resulting in a firm shell with a cavity corresponding to the outline of the pattern.

Shift

A casting defect caused by mismatch of cope and drag, or of cores and mold.

Shot blasting (Shot Peening)

Casting cleaning process employing a metal abrasive (grit or shot) propelled by centrifugal or air force.

Shrink

The difference in volume between liquid metal and solid metal, or the void (shrink hole) left in a casting because of it.

Shrinkage

1) Liquid, contraction in volume as metal cools to solidification, 2) solidification, contraction in volume when the metal passes from the liquid to the sold at the freezing point (may expend over a range), 3) solid, the contraction on cooling from freezing point to normal temperature, 4) the decrease in dimension in clays occurring when drying at 100°C (212°F) and even more so on firing, 5) reduction in dimension of refractory material during heating.

Shrinkage Cracks

Cracks that form in metal as result of the pulling apart of grains by contraction before complete solidification.

Silica Sand

Sand with a minimum silica content of 95% used for forming casting molds.

Simultaneous Engineering

Refers to the process where user/designer and producer interact to reduce lead time and improve the efficiency of a part. This process is faster and more efficient than the traditional sequential process of design and manufacture.

Skimming

Removing or hold back dirt or slag from the surface of the molten metal before or during pouring.

Skin

A thin surface layer different chemically or structurally from the main mass of a metal object.

SLA

Stereolithography Apparatus.

Slag Trap

An enlargement, dam, or extrusion in the gating or runners system in a mold for the purpose of preventing molten slag particles from entering the mold cavity.

Slurry

A term loosely applied to any clay-like dispersion. It may be used to wash ladles or other refractory linings to impart a smooth surface; as a bonding addition to molding sand, as a thin loam over specially made molds, or as a mixture to fine joints or cracks of a core, etc.

Smelting

A metallurgical thermal process in which a metal is separated in fused form from nonmetallic materials, or other undesired metals with which it is associated.

Softening

A process used to soften metals through annealing or tempering.

Solidification

The physical process of change from a liquid to a solid state. See Casting Analysis of Solidification (13kB).

Solidification, Shrinkage

The decrease in size accompanying the freezing of a molten metal.

Spalling

Buckling or flaking off of the surface material.

Specific Gravity

A numerical value representing the weight of a given substance, as compared with the weight of an equal volume of water at 39°F (3.9°C), for which the specific gravity is taken as 1,000 kg/m3.

Specific Heat

Equivalent to thermal capacity, or the quantity of heat required to produce a unit change in the temperature of a unit mass.

Specific Volume

Volume of one gram of a substance at a specific temperature, usually 68°F (20°C).

Spout

A trough through which the metal flows from the furnace to the ladle.

Sprue Hole

The opening through which the metal is poured into the cope to run into the casting cavity.

Stainless Steel

A wide range of steels containing chromium, or chromium and nickel, exhibiting high resistance to corrosion.

Steel

An alloy of iron and carbon that may contain other elements, and in which the carbon content does not exceed about 1.7%; it must be malleable at some temperature while in the as-cast state.

Stereolithography Apparatus (SLA)

Equipment used for computerized building of three-dimensional models and patterns. Enables the data representation of a CAD solid model to be directly converted into a plastic model of a casting.

Stock Allowance

Material added to a part to allow for surface preparation or precise dimensioning by machining.

Stopper Rod

A device in a bottom-pour ladle for controlling the flow of metal through the nozzle into the casting. The stopper rod consists of a steel rod, protecting sleeves, and a graphite stopper head. It may also be a single piece manufactured from graphite.

Streamline Flow

Steady flow of liquid without turbulence. Generally, not experienced in metalcasting.

Stress, Relieving

A heat treatment to reduce residual stresses, followed by sufficiently slow cooling to minimize development of new residual stresses.

Stress, Residual

Those stresses set up in a metal as a result of nonuniform plastic deformation, or the unequal cooling of a casting.

Stress-Corrosion Cracking

Spontaneous failure of metals by cracking under combined conditions of corrosion and stress, either residual or applied.

Structure (Cast Structure)

The size and disposition of the constituents of a metal as cast.

Superalloy

An alloy developed for very high temperature use, where relatively high stresses are encountered, and where oxidation resistance is needed.

Supercooling

Lowering the temperature of a molten metal below its liquidus during cooling.

Superheat

Any increment of temperature above the melting point of a metal; sometimes construed to be any increment of temperature above normal casting temperatures introduced for the purpose of refining, alloying, or improving fluidity.

Supersaturated

Metastable solution in which the dissolved material exceeds the amount the solvent can hold in normal equilibrium at the temperature and under the other conditions that prevail.

Surfacing

Depositing a filer metal on a metal surface by any method to obtain certain desired properties or dimensions.

Swell

A casting defect consisting of an increase in metal section due to the displacement of sand by metal pressure.

Temper

1) Reheating hardened, normalized, or mechanically worked steel to a temperature below the critical range to soften it and improve impact strength. 2) The moisture content of a sand at which any certain physical test value is obtained, e.g., temper with respect to green compressive strength, permeability, retained compressive strength, etc. 3) To mix material with enough liquid to develop desired molding properties.

Temper Brittleness

Brittleness that results when certain steels are held within or cooled slowly through a certain range of temperature below the transformation range. The brittleness is revealed by notched-bar impact tests at room temperature or lower temperatures.

Temper Stressing

Quenching in water from the tempering temperature to improve fatigue strength.

Temperature

Degree of warmth or coldness in relation to an arbitrary zero measured on one or more of accepted scales, as Centigrade, Fahrenheit, etc.

Temperature, Holding

1) Temperature above the critical phase transformation range at which castings are held as a part of the heat treatment cycle, 2) The temperature maintained when metal is held in a furnace, usually prior to pouring.

Temperature, Pouring

The temperature of the metal as it is poured into the mold.

Tempered Martensite

Martensite that has been heated to produce to BCC iron and a fine dispersion of iron carbide.

Tensile Strength

The maximum stress in uniaxial tension testing, which a material will withstand prior to fracture. The ultimate tensile strength is calculated from the maximum load applied during the test, divided by the original cross-sectional area.

Thermal Conductivity

The property of matter by which heat energy is transmitted through particles in contact. For engineering purposes, the amount of heat conducted through refractories is usually given in Btu per hour for one square foot of area, for a temperature difference of one degree Fahrenheit, and for a thickness of one inch, Btu/hr ·ft·F/in.

Thermal Contraction

The decrease in a linear dimension and volume of a material accompanying a change of temperature.

Thermal Expansion

The increase in a linear dimension and volume of a material accompanying a change of temperature.

Thermal Fatigue

Failure resulting from rapid cycles of alternate heating and cooling.

Thermal Shock

Stress developed by rapid and uneven heating of a material.

Thermography

1) The technique of obtaining a photographic record of heat distribution in a solid or fluid.

Tolerance

The permissible deviation of a dimension from the nominal or desired value. Minimum clearance between mating parts.

Tool Steel

Any high-carbon or alloy steel used to make a cutting tool for machining metals and for metal-casting dies.

Toughness

The ability of the metal to absorb energy and to deform plastically during fracture. Toughness values obtained in testing depend upon the test temperature, the rate of loading, the size of the test specimen, as well as the presence of a notch and its acuity.

Transfer Ladle

A ladle that may be supported on a monorail or carried in a shank and used to transfer metal from the melting furnace to the holding furnace, or from furnace to pouring ladles.

Transformation (Temperature) Range

The critical temperature at which a change in phase occurs. To distinguish between the critical points in heating and cooling those in heating are referred to as the Ac points (c for Chauffage or heating) and those in cooling, Ar. (r for Refroidissement).

Turntable

The base on which a centrifugal casting mold rests.

Ultrasonic Testing

A nondestructive method of testing metal for flaws based on the fact that ultrasonic waves are reflected and refracted at the boundaries of a solid medium.

Upgrading

In castings, the removal and repair of discontinuities to raise the quality level of the casting beyond that which can be economically achieved by good foundry practice.

Upper Yield Point (also Yield Point)

Denoted in yield point phenomenon as a distinct break from the elastic region accompanied by a drop in load, yet prior to plastic deformation in the stress-strain curve in a low-carbon steel.

Vacuum Casting

A casting in which metal is melted and poured under very low atmospheric pressure; a form of permanent mold casting where the mold is inserted into liquid metal, vacuum is applied, and metal drawn up into the cavity.

Vacuum Degassing

The use of a vacuum technique to remove dissolved gases from molten alloys.

Vacuum Refining

Melting in a vacuum, usually by electrical induction, to remove gaseous contaminants from the metal.

Venting

Perforation with a vent wire of the sand over and around a mold cavity to assist in the escape of the gases.

Vertical Axis Casting Machine

A centrifugal casting machine in which the axis of rotation of the mold is vertical.

Virgin Metal (Primary Metal)

Metal extracted directly from the ore; not previously used.

Viscosity

The resistance of fluid substance to flowing, quantitatively characteristic for an individual substance at a given temperature and under other definite external conditions.

Void

A shrinkage cavity produced in casting during solidification.

Warpage

Deformation other than contraction that develops in a casting between solidification and room temperature; also, distortion occurring during annealing, stress relieving, and high-temperature service.

Water Test

To subject a casting to water pressure in such a manner that any porous areas will show leakage.

Wax Pattern

1) A precise duplicate, allowing for shrinkage, of the casting and required gates, usually formed by pouring or injecting molten wax into a die or mold, 2) wax molded around the parts to be welded by a termite welding process.

Wear

The undesired deterioration of a component by the removal of material from its surface.

Weld Bead

The built-up portion of a fusion weld, formed either from the filler metal or the melting of the parent metal.

Welding

A process used to join metals by the application of heat. Fusion welding, which includes gas, arc, and resistance welding, requires that the parent metals be melted.

Welding Electrode

A metal or alloy in rod or wire forms used in electric arc welding to maintain the arc, and at the same time supply molten metal or alloy at the point where the weld is to be accomplished.

Welding Shielded-Arc

Electric-arc welding in which the molten weld metal is protected from the atmosphere. An inert gaseous atmosphere or fluxcoated electrode may be employed.

Welding Stress

That stress resulting from localized heating and cooling of metal during welding.

Welding, Arc

Welding accomplished by using an electric arc that can be formed between a metal or carbon electrode and the metal being welded; between two separate electrodes, as in atomic hydrogen welding or between the two separate pieces being welded, as in flash welding.

Welding, Autogenous

Method of uniting two pieces of metal by melting their edges together without solder or any added welding metal, as by the thermite process that employs a medium of finely divided aluminum powder and oxide, or iron by which a temperature of some 2982.2°C (5400°F) is obtained.

X-Ray

Form of radiant energy with wavelength shorter than that of visible light, and with the ability to penetrate materials that absorb or reflect ordinary light. X-rays are usually produced by bombarding a metallic target with electrons in a high vacuum. In nuclear reactions it is customary to refer to photons originating in the nucleus as gamma rays and to those originating in the extranuclear part of the atom as x-rays.

Yield

Comparison of casting weight to total weight of metal poured into mold.

Yield Ratio

The ratio of yield strength to ultimate tensile strength.

Yield Strength

The stress at which a material exhibits a specified limiting permanent strain.

Young's Modulus (E)

In tension it is the ration of stress to the corresponding strain.