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MetalTek International - Metallurgy glossary
Category: Agriculture and Industry > Glossary of Metallurgical Terms
Date & country: 22/08/2013, US
Words: 477


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.

Decarburiztion
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 that 10X) magnification, in a reagent that attacks the metal to a much greater extent than normal for microscopic examination. Gross features my 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.

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

Dexidation
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.

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-Ch...

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.

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

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

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.

Dried Sand
Sand which has been dried by mechanical dryer prior to use in core making.

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

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

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.See Yield Strength

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 a 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 a 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.

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.