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


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.See also Precipitation Hardening

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 167

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. AOD

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.

Artifical 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. (See Finishing)

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/mm

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

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.

Collapsibity
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...

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.