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Home > Glossary of Foundry Terms > I

Glossary of Foundry Terms - I

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ID Grinding

Term for internal dimension grinding.

Ideal Critical Diameter, D1

The largest diameter of a bar which, upon quenching in an ideal quench, will exhibit 50% martensite at the center of the bar. See Quenching.

Ideal Quench

A quench in which the temperature of an object being quenched instantaneously drops to that of the quench bath and remains constant. See Quenching.

Illinois Inclusion Count Method

A determination of the index number of cleanliness of steel. See Inclusion.


A mineral, typically KAl 3Si 3O 10(OH)2, found in many clays, large working of which are found in Illinois and Michigan.

Impact Strength

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

Impact Value

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


Loss of any constituent from an alloy or from localized areas of an alloy by oxidation, liquidation, volatilization, or changes in the solid state. The term depletion is also used, particularly in referring to the lowering of the concentration of solute in a solid solution, around particles precipitated from solid solution.


A treatment process using a sealing medium for salvaging leaky castings by injecting under pressure liquid synthetic resins, tung oil, etc., into the porous area. This material is then solidified in place by heating or baking. Other mediums used include silicate of soda, drying oils with or without styrene, plastics, and proprietary compounds.


Cavity in a die-casting die or in a mold. See Cavity, Mold.


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


Particles of slag, refractory materials, sand or deoxidation products trapped in the casting during solidification. See Dirty Casting, Solidification.


An oxidation-resistant alloy, 80% Ni, 14% Cr, and 6% Fe.

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. See BHN, Brinell Hardness, Hardness.

Indirect-Arc Furnace

An AC, Alternating Current, electric-arc furnace in which the metal is not one of the poles. An electric furnace in which the arc is struck between two horizontal electrodes, heating the metal charge by radiation.

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. See Ac3, 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.

Infrared Dryer

A core or mold dryer employing infrared lamps. See Core Dryers.

Infrared Radiation Pyrometer

This instrument which uses the ratio of the radiated energy from a body in two wavelength bands and then is a measure of the body's surface temperature. Temperatures down to 200°C (392°F) may be measured. See Pyrometer.

Infrared Rays

Pertaining to or designating those rays which lie just beyond the red end of the visible spectrum, such as are emitted by a hot non-incandescent body. They are invisible and nonactinic and are detected y their thermal effect. Their wave lengths are longer than those of visible light and shorter than those of radio waves. Can be applied in the foundry for drying or core baking operations and for heating dies. Infrared radiant heat are synonymous. See Foundry.

Infusorial Earth (Diatomite, Fossil flour, Mountain meal, Mountain flour, Tripolite, Kieselguhr)

A very fine whitish powder composed of the siliceous skeletons of infusorians (Protozoa).


The channels through which molten metal enters the mold cavity. See Gate.


Casting to be later forged or hot worked.  Also, a form used for convenient handling of cast iron, aluminum, and other commercial metals. i.e., Pigs. See Cast Iron.

Ingot Iron

Iron of comparatively high purity produced in open-hearth furnace under conditions that keep down the carbon, manganese, and silicon content; e.g., Armco Iron. See Cast Iron.


Forcing molten metal into a die-casting die. Also refers to forcing oxygen, nitrogen, and other gases, as well as solids such as calcium carbide and graphite, into molten metal.

Injection Molding

The injection of molten metal or other material under pressure into molds. See Molds.


Materials, which when added to molten metal, modify the structure and thereby change the physical and mechanical properties.


A process of adding some material to molten metal in the ladle for the purpose of controlling the structure to an extent not possible by control of chemical analysis and other normal variables.


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

Institue of Scrap Iron and Steel, Inc.

See Trade Name for address.

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. See Solidification.

Insulating Sleeve

Hollow cylinders or sleeves formed of gypsum, diatomaceous earth, pearlite, vermiculite, etc. Placed in the mold at sprue and riser locations to decrease heat loss and rate of solidification of the metal contained in them. See Riser, Sprue.

Integral Dose (Volume Dose)

A measure of the total energy absorbed by man or any object during exposure to radiation.

Intensity (Radiology)

Amount of energy per unit time passing through a unit area perpendicular to the line of propagation at the point in question. Often this term is used incorrectly in the sense of dose rate.

Intercast Process

A patented procedure for die casting "cast-assemble" units with moving parts.

Intercrystalline Failure

Cracks or fractures that follow along the grain boundaries in the microstructure of metals and alloys.

Interdendritic Attack

A type of electrochemical corrosion that sometimes occurs in as-cast alloys or alloys that have had very little working.

Intergranular Corrosion

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

Internal Chills

Solid pieces of metal or alloy, similar in composition to the casting, placed in the mold prior to filling it with molten metal. They increase the rate of solidification in their areas and are employed only where feeding is difficult or impossible.

Internal Friction

Ability of a metal to transform vibratory energy into heat; generally refers to low stress levels of vibration; damping has a broader connotation since it may refer to stresses approaching or exceeding yield strength.

Internal Shrinkage

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

Internal Stresses (or Thermal stresses)

Generally stresses which occur during the cooling of a part.

International Molders & Allied Workers Union of America

International Molders & Allied Workers Union of America - see trade associations.

Interrupted Quench

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


An alloy having practically no expansion when heated; 36% Ni, 0.5% Mn, 0.2% C, and the balance Fe.

Inverse Chill

A condition in an iron casting section in which the interior is mottled or white while the outer sections are gray. This condition is also called reverse chill, internal chill, or inverted chill.

Inverse Segregation

A concentration of certain alloy constituents that have lower melting points in the region corresponding to that first solidifying; caused by interdendritic flow of enriched liquid through channels where the pressure drops with contraction of dendrites. The internal evolution of hydrogen may also give a positive pressure, aiding this flow and causing a liquidated surface as tin sweat. See Segregation.


A change in crystal form without change in chemical composition, as from quartz to cristobalite.

Inversion Casting

The metal is fed through a bottom feeder, the mold being inverted for pouring.


The process of pouring the investment slurry into the flask surrounding the pattern to form the mold. See Flask, Mold.


A flowable mixture of a graded refractory filler, a binder and a liquid vehicle which when poured around the patterns conforms to their shape and subsequently set hard to form the investment mold. See Investment Casting.

Investment Casting

A pattern casting process in which a wax or thermoplastic pattern is used. The pattern is invested (surrounded) by a refractory slurry. After the mold is dry, the pattern is melted or burned out of the mold cavity, and molten metal is poured into the resulting cavity. See Lost Wax Process.

Investment Casting Process

A pattern casting process in which a wax or thermoplastic pattern is used. The pattern is invested (surrounded) by a refractory slurry. After the mold is dry, the pattern is melted or burned out of the mold cavity, and molten metal is poured into the resulting cavity. See Mold Cavity.

Investment Molding

Method of molding using a pattern of wax, plastic, or other material which is "invested" or surrounded by a molding medium in slurry or liquid form. After the molding medium has solidified, the pattern is removed by subjecting the mold to heat, leaving a cavity for reception of molten metal. This is also called the lost-wax process or precision molding. See Lost Wax Process, Investment Casting.

Investment Precoat

An extremely fine investment coating applied as a thin slurry directly to the surface of the pattern to reproduce maximum surface smoothness. The coating is surrounded by a coarser, cheaper, and permeable investment to form the mold. See Dip Coat.

Inwall Brick

Refractory lining of the inwall section of blast furnace or cupola. See Blast Furnace, Cupola, Refractory.


The process or the result of any process by which a neutral atom or molecule acquires either a positive or a negative charge.

Ionization Chamber

An instrument designed to measure quantity of ionizing radiation in terms of the charge of electricity associated with ions produced within a defined volume.



A noble metal of the platinum group. Usually extensively as a radiation source. For radiography of thin walled castings.


A metallic element, mp 1535°C (2795°F). Also irons that do not fall into the steel categories, such as Gray Iron, Ductile Iron, Malleable Iron, White Iron, Ingot, and Wrought Iron. See Gray Iron, Ductile Iron, Malleable Iron, White Iron, Ingot.

Iron Carbide

See Cementite.

Iron Oxide

This material as prepared for foundry use generally contains about 85% ferric oxide and is produced by pulverizing a high grade of pure iron ore. It can be added to core sand mixes to assist in keeping the core from cracking before the metal solidifies during the casting operation and also helps to resist metal penetration during this period. Added to molding sand mixtures for control of finning and veining. Also may reduce carbon pick up.

Iron Sand

See Iserine.

Iron, Hard Or White

Irons (Fe3C) possessing white fracture because all or substantially all of the carbon is in the combined form. Irons to be malleablized are cast white, as are many abrasion-resistant irons.

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).

Iron, Pearlitic Malleable

A malleable iron having a more or less pearlitic matrix.

Iron, White Or Hard

Iron of suitable composition in which the castings, later to be malleableized, are originally cast. Carbon is in the combined form; hence it’s white fracture and name.

Iron-Carbon (Graphite) Diagram

A diagram representing stable equilibrium conditions between iron and graphite (pure carbon) phase over the entire range of iron and steel.

Iron-Iron Carbide Diagram

A phase diagram representing metastable equilibrium conditions between Fe and Fe3C over the entire range of carbon steels and cast irons.


A black sand which consists mainly of magnetic iron ore but also contains a considerable amount of titanium.


Trade name of a binder system developed for use in the cold box process of core construction.

Isocyanate Acid

Isomeric cyanic acid (HNCO).


Phases with crystal structures of the same type.


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. See Austenite, Annealing.

Isothermal Transformation

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


One of several different nuclides having the same number of protons in their nuclei, and hence having the same atomic number, but differing in the number of neutrons and therefore in the mass number.


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Atlas Foundry Company, Inc.
601 N. Henderson Avenue
Marion, IN 46952-3348
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