Glossary and Terms of the Foundry Industry

Steel Founders' Society of America

Glossary of Foundry Terms - I

H | Index | J

Ideal Critical Diameter, DI: The largest diameter of a bar which, upon quenching in an ideal quench, will exhibit 50% martensite at the center of the bar.
ICI: See Investment Casting Institute
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.
Ideal Quench: A quench in which the temperature of an object being quenched instantaneously drops to that of the quench bath and remains constant.
Illinois Inclusion Count Method: A determination of the index number of cleanliness of steel.
Illite: A mineral, typically KAl3Si3O10(OH)2, found in many clays, large working of which are found in Illinois and Michigan.
IM and AWI: See International Molders and Allied Workers Union
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.
Impoverishment: 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.
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 unintentional 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.
Inconel: 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 Brinell Hardness and Hardness
Indirect-Arc Furnace: An AC (Alternating Current) electric-arc furnace in which the metal is not one of the poles.
Induction Furnace: A 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.
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.
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.
Infrared Dryer: A core or mold dryer employing infrared lamps.
Infusorial Earth (Diatomite, Fossil Flour, Mountain Meal, Mountain Flour, Tripolite, Kieselguhr): A very fine whitish powder composed of the siliceous skeletons of infusorians (Protozoa).
Ingates: The channels through which molten metal enters the mold cavity.
See Gate
Ingot: A mass of metal cast to a convenient size and shape for remelting or hot working.
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
Injection Molding: The injection of molten metal or other material under pressure into molds.
Inoculant: Material which when added to molten metal modifies the structure, and thereby changes the physical and mechanical properties to a degree not explained on the basis of the change in composition resulting from its use.
Inoculation: Addition to molten metal of substances designed to form nuclei for crystallization.
Also see Inoculant
Insert: A part usually formed from metal, which is placed in a mold and may become an integral part of the casting.
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.
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 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.
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.
Invar: An alloy having practically no expansion when heated; 36% Ni, 0.5% Mn, 0.2% C, and the balance Fe.
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 also Segregation
Inversion: A change in crystal form without change in chemical composition, as from quartz to cristobalite.
Inversion Casting: 1) The metal is fed through a bottom feeder, the mold being inverted for pouring, 2) the mold is directly attached to the electric furnace in which the metal is melted in a reducing atmosphere so no slag is formed. On inverting the furnace the metal runs into the mold. There are no heavy feeders and oxidation is prevented.
Investing: The process of pouring the investment slurry into the flask surrounding the pattern to form the mold.
Investment: 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.
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.
Investment Casting Institute: See Trade Name for address
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.
Ionization: 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.
Iridium: A noble metal of the platinum group. Usually extensively as a radiation source. For radiography of thin walled castings.
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 Carbide: See Cementite
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-Iron Carbide Diagram: A phase diagram representing metastable equilibrium conditions between Fe and Fe3C over the entire range of carbon steels and cast irons.
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, 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 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, Pearlitic Malleable: A malleable iron having a more or less pearlitic matrix.
Iron Sand: See Iserine
Iserine: A black sand which consists mainly of magnetic iron ore but also contains a considerable amount of titanium.
ISO: International Standards Organization.
See Trade Name for address
Isocure: Proprietary name for a binder system developed for use in Ashland (Cold Box) Process, itself a proprietary process.
Isocyanate Acid: Isomeric cyanic acid (HNCO).
Isomorphous: Phases with crystal structures of the same type.
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.
Isotope: 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.