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MetalTek International - Metallurgy glossary
Category: Agriculture and Industry > Glossary of Metallurgical Terms
Date & country: 22/08/2013, USA
Words: 473

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.

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.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.

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.

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

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.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
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.

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

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.

1) A metallic element, mp 1535

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).

International Standards Organization.

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

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.

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.

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.

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.

Machine Drawing
An engineering drawing which depicts the final size and shape of the part for its end use.

Magnetic Particle Inspection
A nondestructive method of inspecting the surface integrity of ferromagnetic materials.

(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.

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

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 rate and on the rate of temperature change during heat treatment.

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.

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.

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.

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.

The temperature at which martensite formation finishes during cooling.

Etching of metal samples for examination under the microscope.

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

Examination by means of a microscope.

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.

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

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

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.

A method of identifying metallic constituents using spectrographic arc.

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

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.

Removing metal with a milling cutter.

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

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 Modulus

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.

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%).See also Naturally Bonded Molding Sand

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.

National Association of Corrosion Engineers

National Bureau of Standards

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

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.

Non-Ferrous Founder's Society

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

National Industrial Sand Association

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