Mechanical Engineering Dictionary-Materials

Important Terms and their Meaning of Mechanical Engineering-Materials:

ABRASIVE – A natural or artificial material such as sand stone, emery, aluminium oxide or silicon carbide.

ACID – A chemical term to define a material which gives an acid reaction.

ADDITIVES – Chemicals added to oil or fuel to increase its effectiveness and obtain desirable qualities.

ADHESIVES – Materials or compositions that enable two surfaces to join together. An adhesive is not necessarily a glue, which is considered to be a sticky substance, since many adhesives are not sticky.

AGGREGATE – Small particles such as powders that are used for powder metallurgy, that are loosely combined to form a whole, also sand and rock as used in concrete.

ALLOTROPIC METALS – Metals which exist in one lattice form over a range of temperature, but at a certain temperature the lattice form changes to another type which is stable over another temperature range.

ALLOY – A substance having metallic properties and is composed of two or more chemical elements, of which at least one is a metal.

ALLOYING ELEMENTS – Elements either metallic or non-metallic added intentionally to the base metal, to make a marked change in the properties of the base metal and to secure certain desirable properties.

ALLOY STEEL – Steel containing significant quantities of alloying elements (other than carbon and the commonly accepted amounts of manganese, silicon, sulphur and phosphorus) added to effect changes in mechanical and physical properties.

ALNICOS – Alnicos materials are composed mainly of aluminium, nickel, cobalt and iron. Some include additions of copper and titanium. They are high-coercive force, high magnetic energy alloys.

ALOXITE – Artificial abrasive material used in the manufacture of grinding wheels. Essentially it consists of alumina, or aluminium oxide, the chemical symbol for which is Al2O3·

ALPHA IRON – The body centered cubic form of pure iron, stable below 1025°C.

ALUMEL – A nickel base alloy containing about 2.5% Mn, 2% AI, and

1 % Si, used chiefly as a component of pyrometric thermocouples.

ALUMINIUM – Greyish white metal, very light in weight, and having in its pure form low mechanical strength, frequently alloyed with other elements to improve its physical characteristics.

ALUMINIUM ALLOY – Aluminium which is alloyed with other metals to give it strength and desirable properties.

ALUMINIUM BRONZE – Alloy containing 90% copper and 10% aluminium, extensively used for die casting.

ANTIFREEZE – A chemical added to the coolant in order to lower its freezing point.

ANTIFRICTION BEARINGS – Ball, roller and needle bearings exhibit very low friction and are suitable for very high speeds, and high loading.

ANTIMONY – Brittle, bluish white metallic element designated Sb. Melting point 630°C. Used as a constituent in some alloys, for instance, bearings and storage battery plates.

ARGON – An inert gas used in certain welding and heat treatment processes.

ARSENIC – A brittle, greyish metallic element designated As. Melting point 814°C. Used as a constituent in some alloys, and in the manufacture of lead shot.

ASBESTOS – A fibrous organic mineral that is non-combustible, non-conducting and acid resistant.

ATOM – The smallest particle of an element.

AUSTENITE – A solid solution of iron and carbon and sometimes other elements in which gamma iron, characterized by a face centered crystal structure, is the solvent. This is stable only within a particular range of composition and temperature, and is non-magnetic.

AUSTENITIC CAST IRON – Cast iron containing such a proportion of alloying constituents (nickel, chromium, copper or manganese) that the structure in the cast state is completely austenitic at ordinary temperatures.

BABBITT METAL – White metal bearing alloy, suitable for bearings subjected to moderate pressures, contains tin 59.5% min, copper 2.25- 3.75%, antimony 9.5-11.5%, lead 26% min, iron 0.08% max, bismuth 0.08% max.

BACKING SAND – Foundry sand placed next to the facing sand after the latter is in place. It forms the bulk of sand used to complete the mould.

BAINITE – A structure in steel named after E.G. Bain that forms between 481° C and the M’s temperature. At the higher temperatures, it is known as upper or feathery bainite. At the lower temperatures it is known as lower or a acicular bainite and resembles martensite.

BAKELITE – Trade name for one of the first used thermo-setting synthetic resins. It is derived from the name of the inventor Dr. L.H. Backeland, and its formation is the result of a chemical action between formaldehyde and phenol.

BAR – A piece of material thicker than sheet, long in proportions to its width or thickness, and whose width to thickness ratio is much smaller than sheet or plate, as low as unity for squares and rounds.

BARK – The decarburized layer just beneath the scale that results from heating steel in an oxidizing atmosphere.

BASE METAL – Metal present in the alloy in largest proportion.

BEARING METALS – Metals (alloys) used for that part of a bearing which is in contact with the journal e.g., bronze or white metal, used on account of their low coefficient of friction when used with a steel shaft.

BELFAST SAND – Red moulding sand of fine grain, and good bonding qualities with moderate refractoriness, suitable for use as facing sand.

BELL METAL – High tin bronze, used in the casting of bells, which is composed of up to 30% tin, together with some zinc and lead

BESSEMER STEEL – Steel manufactured in a Bessemer converter, and sometimes referred to as mild steel.

BILLET – A solid semi finished round or square product that has been hot worked by forging, rolling or extrusion.

BLUE VITRIOL – A chemical mixture of copper sulphate, water and sulphuric acid. Applied to polished metal for layout purposes, it turns to copper colour.

BOND – In grinding wheels and other relatively rigid abrasive products, the material that holds the abrasive grains together. In welding, the junction of joined parts.

BORON CARBIDE – An abrasive used in cutting tools, a compound whose chemical formula is B4 C and obtained from boron trioxide (B2O3) and coke at a temperature of 2500°C. Fine powder as hard as diamond.

BRASS – A range of copper zinc alloys, usually those containing 55-80% copper. Alloys containing not less than 63% of copper are called ALPHA BRASSES. When less than 63% of copper is present, the alloy is called ALPHA-BETA alloy.

BRAZING ALLOY – Copper zinc alloy, which sometimes includes small percentages of tin, and lead, used for brazing, the melting point of which is governed by the percentage of zinc.

BRINE – Water that has been saturated or nearly saturated with salt.

BRIQUETS – Compact cylindrical or other shaped blocks formed of finely divided materials by incorporation of a binder, by pressure, or both.

Materials may be ferroalloys, metal borings or chips, silicon carbide etc.

BRONZE – A copper rich, copper tin, copper lead or copper beryllium alloy to which often alloying elements (phosphorous, aluminium, zinc, silicon) may be added. Usually bronze is a copper tin alloy containing 90% copper and 10% tin.

BUILDING BRICK – These are made from clay. Generally, the clay is mixed with water to a plastic state and extruded in a column that is wire-cut crosswise to the desired size. Occasionally the dry pressing process is used.

CADMIUM – White ductile metallic element used to plate steel and as an alloying element.

CALCIUM ALUMINIUM SILICON – An alloy composed of 10-14% calcium, 8-12% aluminium, and 50-53% silicon used for degasifying and deoxidizing steel.

CALCIUM BORIDE – An alloy of calcium and boron, containing about 61% boron and 39% calcium and used in de-oxidation and degasification of non-ferrous metals and alloys.

CALCIUM CARBIDE – A greyish black, hard crystalline substance made in the electric furnace by fusing lime and coke. Addition of water to calcium carbide forms acetylene and a residue of slaked lime.

CALCIUM MANGANESE SILICON – An alloy containing 17 to 19% calcium, 8 to 10% manganese, 55 to 60% silicon and 10 to 14% iron, used as a scavenger for oxides, gases and non-metallic impurities in steel.

CALCIUM MOLYBDATE – A crushed product containing 40-50% molybdenum, 23-25% lime, 3% iron (max) and 5-10% silica, used to add molybdenum to iron and steel produced in open hearth, air furnace or electric furnace.

CALCIUM SILICON – An alloy of calcium, silicon and iron containing

28-35% calcium, 60-65% silicon and 6% max iron used as a deoxidizer and degasifier for steel and cast iron. Sometimes called CALCIUM SILICIDE.

CAPPED STEEL – Semiskilled steel cast in a bottle top mould and covered with a cap fitting into the neck of the mould. The cap causes the top metal to solidify. Pressure is build up in the sealed in molten metal and results in a surface condition much like that of RIMMED STEEL.

CARBIDE – A compound of carbon with one or more metallic elements.

CARBOHYDRATES – Constitute a large group of molecules, widely distributed in nature, which contains only carbon, hydrogen and oxygen. The simplest carbohydrates are sugars.

CARBON – A non-metallic element found in all organic substances that is used as an alloying element in ferrous metals.

CARBON STEEL – Steel containing carbon up to about 2% and only residual quantities of other elements except those added for de-oxidation, with silicon usually limited to 0.60% and manganese to about 1.65%. Also termed PLAIN CARBON STEEL.

CARBORUNDUM – Artificially manufactured abrasive, trade name for a carbide of silicon (SiC) which is prepared by heating sand with coke in an electric furnace.

CARTRIDGE BRASS – Alloy containing about 70% copper and 30% zinc, in which impurities are kept to a minimum, and it possesses a high degree of strength, combined with good ductility.

CAST ALLOY TOOL – A cutting tool made by casting a cobalt base alloy and used at machining speeds between those for high speed steels and sintered carbides.

CAST IRON – Iron obtained by slightly purifying the pig iron in a cupola or other furnace. This has high carbon content, averaging between 2.5 and 4.5% and frequently alloyed with small percentage of other elements and primarily used for making castings. It is somewhat brittle.

CELLULOSE – A polysaccharide of glucose units that constitutes the chief part of the cell walls of plants. For example, cotton fibre is over 90% cellulose and is the raw material of many manufactured goods such as paper, rayon and cellophane. In many plant cells, the cellulose wall is strengthened by the addition of lignin, forming lignocelluloses.

CEMENT – Material used for uniting other materials so that they adhere permanently.

CEMENTED CARBIDE – A solid and coherent mass made by pressing and sintering a mixture of powders of one or more metallic carbides, and a much smaller amount of a metal, such as cobalt, to serve as a binder.

CEMENTITE – Hard, brittle, crystalline iron carbide (compound of iron and carbon Fe3C) found in steels having high carbon content. It is characterized by an orthorhombic crystal structure. When it occurs as a phase in steel, the chemical composition will be altered by the presence of manganese and other carbide forming elements.

CERAMIC – Metallic oxides of metals such as silicon and aluminium.

CERAMIC MATERIALS – The materials that demonstrate great hardness and resistance to heat and are used to make cutting tools, coatings on tools, parts subjected to very hot conditions, abrasives and mechanical parts.

CERMET (Ceramal) – A body consisting of ceramic particles bonded with a metal.

CESIUM 13T – A radioisotope, recovered as a fission product from nuclear reactors, with a half-life of 33 years and a dominant characteristic gamma radiation of 0.66 MeV. It is suitable as a gamma radiation source, especially in radiography and therapy.

CHILL – (1) A metal insert embedded in the surface of a sand mould or core or placed in a mould cavity to increase cooling rate at that point. (2) White iron occurring on a gray iron casting such as the chill in the wedge test.

CHINESE SCRIPT – An angular micro-structural form with the constituents’ alpha (AI-Fe-Si) and alpha (AI-Fe-Mn-Si) in cast aluminium alloys. A similar microstructure is found in cast magnesium alloys containing silicon as Mg2Si.

CHROMEL – (1) 90% Ni, 10% Cr alloy used in thermocouples. (2) A series of Nickel chromium alloys some with iron, used for heat resistant applications.

CHROMIUM – Greyish white metallic element obtained from chromites, chemical symbol is Cr and melting point 1830°C, used in alloying steels and corrosion resisting plating.

CLAD METAL – A composite material containing two or three layers that have been bonded together. The bonding may have been accomplished by rolling, welding, casting, heavy chemical deposition or heavy electroplating.

COAL TAR – Also called crude oil, when subjected to fractional distillation and purification, yields a variety of useful products-neutral, acidic, and base oils.

COBALT-60 – A radio isotope with a half-life of 5.2 years and dominant characteristic gamma radiation energies of 1.17 and 1.33 MeV. It is used as a gamma radiation source in industrial radiography and therapy.

COLD FINISHED STEEL – Steel bar which has been cold drawn/cold rolled, centerless ground or turned smooth to improve surface finish, accuracy or mechanical properties.

COLD ROLLED STEEL – Steel which has been passed through rollers at the steel mill to size it accurately and smoothly.

COLLOIDS – Finely divided material, less than 0.5 micron in size, gelatinous, highly absorbent and sticky when moistened.

COLUMNAR STRUCTURE – A coarse structure of parallel columns of grains having the long axis perpendicular to the casting surface.

COMBINED CARBON – The part of the total carbon in steel or cast iron that is present as other than FREE CARBON.

COMPOSITE FIBRES – The strands of material used as reinforcement extending through a resin or other matrix in a composite material. An example is carbon fibres in an epoxy matrix. Loads applied to the structure are carried by the fibres.

COMPOSITE MATERIAL – Materials exhibiting a much higher strength than the matrix or base material because of reinforcement fibres.

CONDUCTORS (electrical) – Materials in which an electromotive force causes appreciable drift of electrons, called CURRENT.

CONSTANTAN – A group of copper nickel alloys containing 45-60% copper with minor amounts of iron and manganese and characterized by relatively constant electrical resistivity irrespective of temperature used in resistors and thermocouples.

CONVERSION COATING – A coating consists of a compound of the surface metal produced by chemical or electro-chemical treatments of the metal.

COPPER – A reddish, soft, ductile metal with very good heat and electrical conductivity and is the basic element in brass and bronze.

CORE – (1) In a metal casting, the hollow parts (which cannot be shaped as easily by the pattern) that are made by using formed sand shapes that are strengthened by baking or by using epoxy. (2) In a ferrous alloy, the inner portion that is softer than the outer portion or case.

CORE SAND – Variety of silica sand. Rock sand, river bed and sea shore sand, commonly known as sharp sand, used for making of cores in the foundry because they are capable of withstanding high temperatures, and resisting the penetrating action of the molten metal.

CORUNDUM – Natural abrasive of the aluminium oxide type that has higher purity than emery.

ROCUS CLOTH – A very fine abrasive polishing cloth.

CHROMIUM BRONZE – It is a precipitation hardening alloy of copper with up to 1 per cent chromium. It has high electrical conductivity and high temperature resistance.

CRUCIBLE – A vessel or pot, made of refractory substance or of a metal with a high melting point, used for melting metals or other substances.

CRUCIBLE STEEL – A high grade steel made by melting iron in a crucible and adding charcoal, pig iron and some substance rich in carbon so that the resulting metal will contain from 0.75-1.5% carbon. This steel is used for tools, dies and better grades of cutlery.

CRYSTAL – A solid composed of atoms, ions or molecules arranged in a pattern which is repetitive in three dimensions.

CRYSTALLOID – A substance that forms a true solution and is capable of being crystallized.

CUNIFE – Cunife is a copper-nickel iron alloy that is malleable, ductile and machinable, even in an age-hardened form. Magnets are formed from wire stock in round, square, or rectangular form.

CUPRO NICKEL ALLOY – Alloy of nickel and copper (approximately 60% nickel and 30% copper), which combines the strength of steel with immunity from corrosion and resistance to high temperature.

CURIE – The quantity of a radioactive nuclide in which the number of disintegrations per second is 3. 700 × 10 to the power of ten.

CUTTING FLUID – A fluid, usually a liquid, used in metal cutting to improve finish, tool life or dimensional accuracy.

DEGASIFIER – A material employed for removing gases from metals and alloys.

DELTA IRON – An allotropic (polymorphic) form of iron, stable above 1390°C, crystallizing in the body centered cubic lattice.

DENDRITE – A crystal that has tree like branching pattern, being most evident in cast metals slowly cooled through the solidification range. Dendrite generally grows inward from the surface of a mould.

DEOXIDIZER – A substance that is used to remove either free or combined oxygen from molten metals, for example, ferrosilicon in steel making.

DEVELOPER – (1) In photography, a processing solution that reduces the exposed grains of an emulsion to metallic silver, thus making the image visible. (2) In zero radiography a dry powder used to make the electrostatic image visible. (3) In penetrant inspection, a material used to draw the penetrant back to the surface, thus revealing locations of cracks or fissures.

DEVIZES SAND – Coarse greenish yellow moulding sand, suitable for dry sand work in the foundry for medium and heavy castings, but not for fine work, owing to its large grain size.

DIAMAGNETIC SUBSTANCES – Actually set up fields that oppose applied fields.

DIAMOND – Allotropic form (crystalline form) of carbon (the hardest known mineral) which when very strongly heated, changes to graphite.

Used as a cutting tool, and a grinding tool and to dress grinding wheels.

DROSS – The scum that forms on the surface of molten metal’s, largely because of oxidation but sometimes because of the rising of impurities to the surface.

DRY SAND MIXTURE (Mould) – Specially prepared and for making the moulds that are to be dried before using. This demands sand that when dried or baked will give strength, porosity and permeability.

DUCTILE IRON – A high strength type of cast iron that will bend without fracturing.

DURALUMIN – Aluminium alloy containing copper, manganese and magnesium, which can be cast, forged or stamped, and is widely used for sheets, tubes, forgings, rivets, nuts, bolts and similar parts.

DYE PENETRANT – Penetrant with a dye added to make it more readily visible under normal lighting conditions.

ELASTOMER – Any of various elastic substances resembling rubber.

ELECTRIC STEEL – Special alloy steel, tool steel, and steel for castings, melted in electric furnaces that permit very close control and the addition of alloying elements directly into the furnaces.

ELECTRICAL INSULATING MATERIALS – The materials which offer a very large resistance to flow of current, and for that reason they are used to keep the current in its proper path along the conductor.

ELECTRICAL SHEETS – It is the trade name for iron and a steel sheet used in the manufacture of punching for laminated magnetic circuits and usually refers to silicon steel sheets.

ELECTROLYTE – A non-metallic conductor, usually a fluid, in which electric current is carried by the movement of ions.

ELECTROMAGNET – A magnet of variable strength produced by passing current through conductors around a soft iron core.

ELEKTRON – Magnesium base alloy supplied in the form of tubes, sheets, extruded sections, forgings and castings.

ELEMENT – A substance which cannot be chemically broken down to simpler substances.

EMERY – An abrasive material which, like corundum or aluminium oxide type, is a natural abrasive.

EMULSIFIER – (1) A material that increases the stability of dispersion of one liquid in another. (2) In penetrant inspection, a material that is added to some penetrant after the penetrant is applied to make a water washable mixture.

ENAMEL – Type of paint that dries to a smooth, glossy finish.

ERITH SAND – Yellow, close grained, refractory moulding sand, having good strength and reasonable permeability.

EUTECTIC – Mixture (an alloy) in which the proportions of the constituents are such that the mixture has a lower melting point than any of the constituents.

FACING SAND – Sand that forms the face of the mould which comes in contact with the molten metal.

FALKIRK SAND – Moulding sand with a coarse, open texture. It has very good permeability and moderate binding qualities.

FERRIC OXIDE – Red iron oxide, commonly available as haematite ore. Used in ground form in cores and moulds to increase hot compressive strength.

FERRITE – A solid solution of one or more elements in body centered cubic iron. Iron which contains little or no carbon. It is very soft and ductile and is known as alpha iron. A magnetic form of iron.

FERROALLOYS – Alloys containing of certain elements combined with iron, and used to increase the amount of such elements in ferrous metals and alloys. In some cases the ferroalloys may serve as deoxidizers.

FERROALUMINIUM – An alloy of iron and aluminium containing about 20% iron and 80% aluminium.

FERROCHROMIUM – An alloy of iron and chromium available in several grades containing from 60-72% chromium and from 0.06-7% carbon.

FERROMAGNETIC MATERIAL – A material that in general exhibits the phenomena of hysteresis and saturation, and whose permeability is dependent on the magnetizing force.

FERROMANGANESE – An alloy of iron and manganese containing from 78-82% manganese.

FERROMOLYBDENUM – An alloy of iron and molybdenum containing 58-64% molybdenum.

FERROPHOSPHOROUS – An alloy of iron and phosphorous containing 70% iron and 25% phosphorous.

FERROSILICON – An alloy of iron and silicon available in several grades containing different percentages of silicon from 14-20% silicon, 42-52% silicon, 69.5-82% silicon, 82-88% silicon and 88-95% silicon.

FERROUS – From the Latin word FERRUM meaning iron, describes an alloy containing a significant amount of iron.

FERROUS METALS – All metals that are alloys of iron, carbon, and other materials.

FIBRE GLASS – A resin matrix reinforced with glass fibres for strength. A reinforced plastic manufacturing material with many applications.

FILTER – In radiography a device, usually, a thin metallic layer inserted into a beam of radiation so as to modify the transmitted spectrum of radiation. It may be used to enhance or reduce contrast or minimize undesirable scattered radiation.

FIRE BRICK – Brick made of refractory clay or other material which resists high temperatures.

FIRE CLAY – A type of clay which is resistant to high temperatures.

FIXER (hypo) – A photographic processing solution, the principle function of which is to dissolve the undeveloped silver halide grains from the developed film, thus making the image more prominent. It often serves also to harden the gelatine and halt the developing process.

FLUX – A solid, liquid or gaseous material that is applied to solid or molten metal in order to clean and remove oxides.

FOAM RUBBER – It is also called sponge. Foam rubbers are formed by the inclusion of chemicals in rubber compounding which form gases during vulcanization.

FREE CARBON – The part of the total carbon in steel or cast iron that is present in the elemental form as graphite or temper carbon.

FREE FERRITE – Ferrite that is structurally separate and distinct as may be formed without the simultaneous formation of carbide when cooling hypo eutectoid austenite into the critical temperature range.

GAMMA IRON – The face centered cubic form of pure iron, stable from 910-1230°C.

GANGUE – The worthless portion of an ore that is separated from the desired part before smelting is commenced.

GEL COAT – A thin coat of plastic resin covering fibreglass panels.

GILDING METAL – Alloy containing 80-90% copper, the reminder being zinc. Often used in wire form for jewellery and decorative applications.

GLACIER METAL – Tin base alloy used for lining bearings.

GLASS – Transparent substance produced by the fusion of sand and certain metallic salts, of which soda compounds are most common.

GLUE LAMINATED BEAM – A structural wood beam made by gluing thinner boards together until a desired dimension for beam thickness is reached. Glue laminated beam will support large loads and can span long distances with only end support.

GRAIN – Individual crystal in metals.

GRANITE – A rock composed of quartz, feldspar and mica from which dimensionally stable surface plates and angle plates are made.

GRANULAR PEARLITE – A structure formed from ordinary lamellar pearlite by long annealing at a temperature below but near to the critical point, causing the cementite to spherodize in a ferritic matrix.

GRAPHITE – Native carbon in hexagonal crystals, also foliated or granular massive, of black colour with metallic lusture, and soft.

GRAPHITE FIBRE – Strands of carbon in graphite form used in composite materials as the main load bearing constituent.

GRAPHITIZER – Any substance, such as silicon, titanium, aluminium etc. which promotes the formation of graphite in cast iron compositions.

GRAY CAST IRON – A cast iron that gives a gray fracture due to the presence of flake graphite. Often called GRAY IRON.

GRIT SIZE – Nominal size of abrasive particles in a grinding wheel corresponding to the number of openings per linear inch in a screen through which the particles can just pass. Sometimes called GRAIN SIZE.

GUN METAL – Bronze alloy containing 88-89% copper, 5-10% tin and 2-6% zinc, lead up to 20% may also be added, although the quantity seldom exceeds 5%.

HALF LIFE – The characteristic time required for half of the nuclei of a radioactive species to disintegrate spontaneously.

HALF VALUE LAYER – In radiation, the thickness of absorber that will reduce the intensity of radiation to one half. It is useful in estimating radiographic exposure.

HIGH CARBON STEEL – Steel that has more than 0.6% carbon.

HIGH SPEED STEEL – Alloy steel (alloying elements being tungsten, chromium, vanadium, cobalt and molybdenum) which retains its strength and hardness at red heat, and is thus suitable for cutting tools which reach high temperatures in use.

HINDU MINIUM – A high strength aluminium alloy containing, in addition to aluminium, magnesium, iron, titanium, copper, nickel and silicon, which after heat treatment has a strength exceeding that of mild steel.

HOT ROLLED STEEL – Steel rolled to shape while being heated to the plastic condition.

HOYT METAL – Commercial grade of white metal used for bearing purpose.

HYPER EUTECTIC ALLOY – Any binary alloy whose composition lies to the right of the EUTECTIC on an equilibrium diagram and which contains some eutectic structure.

HYPO EUTECTIC ALLOY – Any binary alloy whose composition lies to the left of the EUTECTIC on an equilibrium diagram and which contains some eutectic structure.

IMPURITIES – Elements or compounds whose presence in a material is undesired.

INCONEL – Nickel alloy highly resistant to heat and corrosion, with good mechanical properties, consisting of 80% nickel, 12-14% chromium, the balance being iron.

INERT GAS – A gas that may be used as a shield in welding or heat treatment to prevent oxidation or scaling.

INGOT – A large block of metal that is usually cast in a metal mould and forms the basic material for further rolling and processing.

INGOT IRON – Commercially pure open hearth iron.

INSULATING MATERIALS (electrical) – Materials which offer a very large resistance to flow of current and for that reason they are used to keep the current in its proper path along the conductor.

INOCULATED IRONS – Inoculated irons are high strength irons of such composition that they would ordinarily be white as cast are often inoculated in the ladle with a silicon compound to cause graphitization. Typical agents used are ferrosilicon, calcium silicide, Si-Mn-Zr, or Ca-Mn-Si in crushed form.

INVAR – Nickel iron alloy (35-36% nickel, 0.5% carbon and 0.5% manganese, the remainder being iron) having a very low coefficient of thermal expansion at ordinary temperatures.

ION – An atom, or group of atoms, that has gained or lost one or more outer electrons and thus carries an electric charge. Positive ions, or cat-ions, are deficient in outer electrons. Negative ions or anions, have an excess of outer electrons, thus ion is electrostatically charged.

IRIDIUM 192 – A radio isotope with a half-life of 74 days and 12 dominant characteristic gamma radiation energies ranging from 0.14-0.65 MeV. It is suitable as a gamma radiation source, mostly in radiography.

IRON – Silver white metallic element, symbol Fe, and melting point 1535°C. Pure iron consists of homogenous crystal grains generally referred to as ferrite.

IRON (wrought) – Malleable iron produced from molten pig iron by a working or puddling process which removes the impurities.

KANTHAL – It is an electrical resistance alloy of iron-chromium-aluminium with small additions of cobalt. About 25 per cent Cr, 5 per cent Al, 3 per cent Co, and balance almost pure iron.

KAOLIN – A fine white clay that is used in ceramics and refractories composed mostly of kaolinite, a hydrous silicate of aluminium. Impurities may cause various colours and tints.

KILLED STEEL – Steel that has been deoxidized with agents such as silicon or aluminium to reduce the oxygen content to such a level that no reaction occurs between carbon and oxygen during solidification. This prevents gases from evolving during solidification.

LACQUER – A quick drying automotive paint.

LAMELLAR – An alternating plate like structure in metals (as in pearlite).

LAMINATE – (1) A composite metal, usually in the form of sheet or bar, composed of two or more metal layers so bonded that the composite metal forms a structural member. (2) To form a metallic product of two or more bonded layers.

LAMINATIONS – Metal defects with separation or weakness generally aligned parallel to the worked surface of the metal.

LASER – Light Amplification by Simulated Emission of Radiation. A device in which heat is derived from the intense coherent beam of laser light energy. This intense, narrow beam of light is used in some welding and machining operations.

LEAD – Heavy, bluish grey, soft, ductile metal, which has a specific gravity of 11.3 and a melting point of 327°C, extensively used alone, and as the basis of many antifriction alloys.

LEAD SCREEN – In radiography, a screen is used (1) to filter out soft wave or scattered radiation and (2) to reduce the intensity of the remaining radiation so that the exposure time can be decreased.

LEDEBURITE – The eutectic of the iron carbon system, the constituents being austenite and cementite. The austenite decomposes into ferrite and cementite on cooling below the transformation temperature.

LIGNIN – A substance that is related to cellulose, that with cellulose forms the woody cell walls of plants and the material that cements them together. Methyl alcohol is derived from lignin in the destructive distillation of wood.

LOAM – Clayey sand mixture having the consistency of slime, and used in the making of moulds and cores for heavy castings.

LOW CARBON STEEL – Steel containing less than 0.3% carbon.

LUTE – Fine adhesive composition of substances such as clay, sharp sand, plumbago and horsedung tempered with water. Used for sealing joints in moulds and cores, for the purpose of making them air or metal tight.

MAGNESIUM – A very light metal (about 106 Ibs/cuft) that alloys readily with aluminium and other metals.

MAGNESIUM ALLOY – Alloy containing at least 85% of magnesium and having a specific gravity of 1.8, alloying elements include aluminium, manganese, zinc, and silicon. Widely used for aircraft components, their weight is only two thirds that of aluminium, and a quarter of that of steel.

MAGNETICALLY HARD ALLOY – A ferromagnetic alloy capable of being magnetized permanently because of its ability to retain induced magnetization and magnetic poles after the removal of externally applied fields, an alloy with high coercive force.

MAGNETICALLY SOFT ALLOY – A ferromagnetic alloy that becomes magnetized readily upon the application of a field and that return to practically a non-magnetic condition when the field is removed, an alloy with the properties of high magnetic permeability, low coercive force, and low magnetic hysteresis loss.

MAGNOLIA METAL – White metal bearing alloy containing 4.75-6% tin, 78-80% lead and 15-16% antimony.

MALLEABLE CAST IRON – A cast iron made by a prolonged anneal of WHITE CAST IRON in which decarbonisation or graphitization, or both, takes place to eliminate some or all of the CEMENTITE. The graphite is in the form of temper carbon. This is less brittle than gray cast iron.

MANGANESE – A brittle, hard metallic element used as an alloy in steel to give it toughness to withstand wear and strain.

MANGANESE BRONZE – A group of special alloys, not really bronzes at all, containing about 1% manganese, 60% copper, 40% zinc and small traces of iron, tin, lead or aluminium, the total percentage of these not exceeding 5%.

MARTENSITE – An unstable constituent that is formed by heating and quenching steel. It is formed without diffusion and only below certain temperature known as M’s temperature. Martensite is the hardest of the transformation products of austenite, having an acicular or needle like microstructure.

MATTER – Any substance which occupies space and has weight. The three forms of matter are solids, liquids and gases.

MEDIUM CARBON STEEL – Steel with a carbon content of 0.3-0.6%.

METAL – An opaque lustrous elemental chemical substance that is a good conductor of heat and electricity and when polished, a good reflector of light.

METALLOID – A non-metal that exhibits some, but not all, of the properties of a metal. Examples are sulphur, silicon, carbon, phosphorous and arsenic.

METALLURGY – The science and study of the behaviours and properties of metals and their extraction from their ores.

MILD STEEL – Carbon steel with a maximum of about 0.25% carbon.

MOLECULE – The smallest portion to which a substance may be reduced by subdivision and still retain its chemical identity.

MOLYBDENUM – Element used in alloying steel, including high speed steel. It gives red hardness and increases the strength of steel at high temperatures. It increases the corrosion resistance of stainless steels at high temperatures, increases the machinability of carbon steels and reduces the temper brittleness of aluminium steels.

MONEL METAL – Trade name for a nickel copper alloy (67% nickel, 28% copper, 5% iron, manganese, and silicon combined) which exhibits high strength and toughness and corrosion resistance.

MU METAL – Special alloy of nickel and iron, also containing copper and manganese, requiring only a very small magnetizing force to produce a normal flux density i.e., the alloy is said to have high permeability (Greek letter MU for permeability).

MUNTZ METAL – Alloy of brass family containing 60% copper and 40% zinc used for manufacturing condenser tubes.

MUSIC WIRE – A high carbon steel wire of the highest quality used for making mechanical springs.

MYCALEX – It is the trade name for a ceramic product made up of glass bonded mica flakes that possess a combination of properties found in other insulating materials.

NATURAL RUBBER – Natural rubber is obtained in the form of latex from the sap of Hevea brasiliensis and a few other plants. Crude rubber is coagulated by heat or by addition of electrolytes.

NAVAL BRASS – Alloy containing from 57.5-59.5% copper, 0.6-1.0% tin and not more than 0.75% of impurities, the balance being zinc (addition of tin improves the resistance of the alloy to corrosion by sea water). Used for under-water fittings of marine craft.

NEOPRENE – A synthetic rubber, highly resistant to oil, light, heat and oxidation.

NEUTRON – Elementary nuclear particle with a mass approximately the same as that of hydrogen atom and electrically neutral.

NICHROME – Alloy of nickel and chromium which is practically noncorrosive, can withstand high temperature without oxidation and is used for furnace components.

NICKEL – A strong, greyish, white, ductile metal, which has high resistance to oxidation and corrosion. Therefore, used in pure form for some applications, such as plating. It is more usually alloyed with other metals.

NICKEL BRONZE – Bronze alloy of which there are two main series (1) low nickel bronze (nickel below 5%) used, for bronze castings, and (2) high nickel bronze (nickel over 10%) resistant to heat, and to corrosive attack from chemical liquors.

NICKEL SILVER – Also called GERMAN SILVER. Alloy with composition copper 60%, zinc 20%, and nickel 20%. Class of alloys used in the manufacture of electrical resistance coils and elements, decorative articles for which its lustrous colour (which increases in whiteness with nickel content) make it very suitable, or for heavy duty works such as high pressure steam fittings.

NICROSILAL – A nickel-chromium alloy cast iron having a composition 1.7% carbon, 4.5% silicon, 0.8% manganese, 18.0% nickel, and 2% chromium, the balance is iron.

NIMONIC ALLOY – Nickel base alloy possessing high resistance to heat and corrosion, used for components in gas turbines and jet propulsion engines.

NIRESIST IRON – Alloy cast iron (typical composition 14% nickel, 1.5% silicon, 1 % manganese, and 3% carbon and remainder iron) which possesses exceptional resistance to heat and corrosion.

NISPAN ALLOY – Range of alloys having controlled expansion and elastic properties.

NITENSYL – Group of cast iron which have a tensile strength of 23-25 tons./sq. inch by suitable heat treatment. A typical composition is 1.5% nickel, 1.5% silicon, 2.9% carbon and 0.8% manganese, the balance being iron.

NITRALLOYS – Nitralloys are the steels developed for nitriding process. The commonly used grades contain 0.20 to 0.40 per cent carbon, 0.9 to 1.5 percent Cr, 0.80 to 1.20 per cent Al, and small additions of Mo, Si, and Mn.

NODULAR CAST IRON – A cast iron that has been treated while molten with a master alloy containing an element such as magnesium or cerium to give primary graphite in the spherulitic form.

NODULAR GRAPHITE – Graphite or carbon in the form of spheroids.

NOMAG – Non-magnetic cast iron, used for castings in electric motors and alternators and similar applications. A typical composition is 11% nickel, 1.5% silicon, 3% total carbon, up to 7% manganese, the balance being iron.

NON-FERROUS – Metals and alloys which do not contain any large proportion of iron, examples being brass, copper, aluminium and lead.

NUCLEUS – (1) The first structurally stable particle capable of initiating recrystallisation of a phase or the growth of a new phase and possessing an interface with the parent matrix. (2) The heavy central core of an atom in which most of the mass and the total positive electric charge are concentrated.

NYLON – A group of plastics of nitrogenous structure known as polyamides which are crystalline in nature and can be so processed as to orient the crystals axially thus making the tensile strength of fibres extremely high.

OIL STONE – An abrasive stone that is oiled and used to sharpen cutting tools.

ORANGE PEEL – A pebble grained surface which develops in forming of metals having coarse grains.

ORE – A natural mineral that may be mined and treated for the extraction of any of its components, metallic or otherwise.

OSMIUM – Osmium is the heaviest of all metals (sp gr. 22. 48), which melts at 4900°F and is harder than glass and quartz.

PARAMAGNETIC MATERIALS – These materials are only feebly magnetic.

PARTING SAND – Fine sand used for dusting on sand mould surfaces that are to be separated.

PEARLITE – The laminar mixture of ferrite and cementite in slowly cooled iron carbon alloys as found in steel and cast iron.

PEARLITIC MALLEABLE IRON – Irons made from the same or similar chemical compositions as regular malleable iron, but so alloyed or heat treated that some of the carbon in the resultant material is in the combined form.

PERMANENT MAGNET – Special magnet steel that retains its magnetic power indefinitely.

PETROCHEMICALS – Chemicals derived from petroleum substances or materials manufactured from a component of crude oil or natural gas.

PEWTER – Alloy containing 1.8% lead, 89.4% tin, 7% antimony and 1.8% copper.

PHASE – It is a portion of matter which is homogeneous in the sense that its smallest adjacent parts are indistinguishable from one another.

PHASE DIAGRAM – Phase diagram is also called equilibrium diagram or constitution diagram, indicates the relative amount and composition of phases present in an alloy at a given temperature and pressure, when the alloy is in equilibrium.

PHOSPHOROUS – One of the elements, its chemical symbol is P. Its formula weight is 123.92, specific gravity 1.82, and melting point 44.1°C.

PHOSPHOR BRONZE – Alloy containing 78.5-81.5% copper, 9-11 % tin, 9-11 % lead, 0.05-0.25% phosphorous and 0.75% zinc, has excellent antifriction properties. Used as bearing material.

PHOTON – The smallest possible quantity of an electromagnetic radiation that can be characterized by a definite frequency.

PIG IRON – Iron produced from iron ore in the blast furnace, basic raw material from which all cast iron, wrought iron and steel are made. Usually contains about 4.5% carbon and impurities such as phosphorous, silicon and sulphur.

PITCH – Usually coal tar pitch obtained in the manufacture of coke and distilled off at about 175°C.

PLASMA – An ionized gas of extremely high temperature achieved by passing an inert gas through an electric arc. Plasma arcs are used in welding, cutting and machining processes.

PLASTIC – A certain group of natural and synthetic resins and their compounds that can be moulded, cast, extruded or used for coatings and films.

PLASTIC ELASTOMERS – Plastic elastomers are materials which exhibit the characteristics of rubber, but are of a basic chemical structure that is decidedly different from that of natural rubber.

PLATINUM – It is a silver-white heavy metal, unaffected by acids, air, or a great variety of chemical agents. It is extensively used, either solid or clad, for chemical equipment.

POLYESTERS – Polyesters are a reaction product of polyhydric alcohol and a dibasic acid plus monomer styrene or diallyl phthalate. In combination with glass fibres they form a product which has an outstanding strength weight ratio.

POLYETHYLENES – The product of straight chain polymerization of ethylene and are obtainable as viscous liquids, gums, and tough flexible solids suitable for moulding.

POLYMER – A chemical compound or mixture of compounds formed by polymerization and consisting essentially of repeating structural units.

PORCELAIN – Porcelain is a ceramic product made up of clays, quartz, and feldspar used as high voltage insulator.

POWDER METALLURGY – Forming parts out of powdered metal by compacting the powder into a mould under great pressure and heating it.

PRECIOUS METAL – One of the relatively scarce and valuable metals gold, silver and platinum groups of metals.

PROTON – The positively charged particle in the nucleus of an atom.

PRUSSIAN BLUE – A blue pigment, obtainable in tubes which are used to find hot spots in a bearing.

QUICK SILVER – Metallic mercury.

RADIO ACTIVE ELEMENT – An element which has at least one isotope that undergoes spontaneous nuclear disintegration to emit positive alpha particles, negative beta particles or gamma rays.

RADIO ISOTOPE – An isotope that emits ionizing radiation during its spontaneous decay.

RADIUM – A radioactive element. It is found in nature as radium 226, which has a half-life of 1620 years.

RAZOR STEEL – Steel containing 1.15-1.25% carbon. This steel is forged at 816°C, and hardened at 750-775°C. It is tempered at 230°C to straw colour.

RED BRASS – A brass containing approximately 85% copper, 5% zinc, 5% tin and 5% lead.

RED ROCK SAND – Open grain moulding sand obtained from red sand stone rocks, with good permeability but low bonding qualities.

REFRACTORY – Materials that will resist change of shape, weight, or physical properties at high temperatures say exceeding 1000oC. These materials are usually silica, fire clay, diaspore, alumina and kaolin. They are used for furnace linings.

RESIDUAL ELEMENTS – Elements present in an alloy in small quantities but not added intentionally.

RESIDUE – The material that remains after completion of a chemical or physical process, such as combustion, distillation, evaporation or filtration.

RESISTORS – Poor conductors.

ROUGHING STONE (hone) – A coarse honing stone.

RIMMED STEEL – A low carbon steel (insufficiently de-oxidized) that during solidification releases considerable quantities of gases (mainly carbon monoxide). When the mould top is not capped, a side and bottom rim of several centimetres forms. The solidified ingot has got scattered blow holes and porosity in the center but a relatively thick skin free from blow holes.

RUST – A corrosion product containing hydrated oxide of iron. Applied only to ferrous alloys.

SAND (moulding) – Substance used in foundries for making the moulds.

SCRAP – Materials or metals that have lost their usefulness and are collected for reprocessing.

SEALANT – A sealing agent that has some adhesive qualities, it is used to prevent leakage.

SEMICONDUCTORS – A few substances containing metallic elements have considerably less electrical conductivity. These contain a few electrons to give them conductivity intermediate between metals and insulators.

SEMISTEEL – Cast iron to which a small proportion of mild steel or wrought iron scrap is added during the melting of the pig iron so that the product will have a lower carbon content than the average iron, from 2.5-3.2% and which is tougher.

SILICA – Silicon dioxide, SiO2 occurring in nature as quartz, opal etc.

SILICON – Non-metallic element which can be added to steel, cast iron and non-ferrous alloys. It acts as a DEOXIDIZER, and also tends to form graphite by throwing the carbon out of solution and thereby increases the impact resistance of the steel, and, up to a silicon content of 1.75%, the elastic limit is increased also.

SILICON ALUMINIUM – An alloy of 50% silicon, and 50% aluminium used for making silicon additions to aluminium alloys.

SILICON BRASS – A series of alloys containing 0.5-0.6% silicon, 1-19% zinc and a substantial amount of copper.

SILICON BRONZE – Alloy containing about 90-95% of copper, to which is added silicon and manganese, equivalent in strength to medium carbon steel with resistance to corrosion and fatigue.

SILICON CARBIDE – A refractory and abrasive material made by sand, coke, and saw dust in an electric arc furnace.

SILICON CARBIDE BRIQUETS – Silicon carbide in BRIQUET form used as an inoculants and deoxidizer in cupola melted gray iron.

SILICON COPPER – An alloy of silicon and copper, used as a deoxidizer and hardener in copper base alloys.

SILMANAL – It is the name given to a rather expensive alloy of silver, manganese, and aluminium that has unusual magnetic properties for special applications.

SILVER – A white, ductile metal that is an excellent conductor of heat and electricity.

SILVERY IRON – A type of pig iron containing 8-14% silicon, 1.5% carbon max, 0.06% sulphur max and 0.15% phosphorous max.

SLAG – The more or less completely fused and vitrified matter separated during the reduction of a metal from its ore.

SLURRY – A watery mixture of insoluble material such as mud, lime or plaster of Paris.

SMOG – The irritating haze resulting from the sun’s effect on certain pollutants in the air, notably those from automobile exhaust. Also a mixture of fog and smoke.

SMOKE – Solid or liquid particles under 1 micron in diameter. Particles suspended in air after incomplete combustion of materials containing carbon. The matter in the exhaust emission which obscures the transmission of light.

SODIUM SILICATE – Na2SiO3-Also called water gas.

SOLDERING ALLOY – Fusible alloy used to join together two metallic surfaces with the aid of heat. Soft solder is an alloy of lead and tin, in which the proportions of the two constituents may vary from almost pure lead to almost pure tin.

SOLDERING FLUID – Liquid flux used when soldering.

SOLID SOLUTIONS – Solid solutions are alloys containing alloying elements that are relatively soluble in the base metal in the solid state.

SOLUBLE OIL – Specially prepared oil whose water emulsion is used as a cutting or grinding fluid.

SOLUTE – A substance that is dissolved in a solution and is present in minor amounts.

SOLVENT – A substance that is capable of dissolving another substance and is the major constituent in a solution.

SORBITE – Structure consisting of evenly distributed carbide of iron particles in a mass of ferrite, formed when fully hardened steel is tempered at between 550 and 650°C.

SPELTER – Hard solder used during brazing containing 60% copper, 20% tin and 20% zinc.

SPHEROIDITE – It is the structure in steel, in which cementite takes the form of rounded particles, or spheroids, instead of plates.

STAINLESS STEEL – Steel which resists corrosion by the atmosphere and the attack of acids and which does not scale when subjected to high temperature. Alloy steels containing iron, at least 11 % chromium, nickel, molybdenum and 0.1-1 % carbon.

STEATITE – Steatite is the name given to a fired ceramic product which contains 80 per cent or more talc bonded with ceramic fluxes to a nonporous structure.

STEEL – An alloy of iron and less than 2% carbon plus some impurities and small amounts of alloying elements is known as plain carbon steel. The alloy steels contain substantial amounts of alloying elements such as chromium or nickel besides carbon.

STELLITE – Non-ferrous alloy containing 35-80% cobalt, 10-40% chromium, 0-25% tungsten and 0-10% molybdenum.

SYNTHETIC MATERIALS – A complex chemical compound which is artificially formed by the combination of two or more compounds or elements.

TERNARY ALLOY – An alloy that contains three principal elements.

THERMIT – Powdered form of finely divided iron oxide and aluminium which burns intensely to produce superheated liquid steel at a temperature of about 30.35°C, used for welding wrought iron and steel forgings and castings.

THERMOPLASTICS – Materials which when heated begin to soften at temperatures as low as 56.5°C, and then can be moulded without any change in chemical structure.

THERMOSETTING MATERIALS – Materials that undergo a chemical change when moulded and cannot be resoftend by heating to reshape them.

TIN – A silvery white, soft metal used in solders and as a plating material.

TITANIUM – A strong, greyish metal that weighs less than steel.

TOOL STEEL – A special group of steels that is designed to specific uses, such as heat resistant steels that can be heat treated to produce certain properties mainly hardness and wear resistance.

TROOSTITE – Structure in steel (consisting of very finely divided iron carbide in what is known as “alpha iron”) produced either by tempering a martenistic steel at between 250°C and 450°C or by quenching steel at a speed sufficient to suppress the thermal change point fully.

TUNGSTEN – Hard, greyish, semiprecious metal with very high melting point of 3300°C, used for electrical contacts, filaments in electric lamps etc. Used as an alloying element in high speed steel.

TUNGSTEN CARBIDE – An iron gray powder composed of carbon and tungsten and used in sintered form as a cutting tool material.

TUNGUM BRONZE – Trade name for high strength bronze.

TWIN CRYSTAL – A crystal grain in which the crystal lattices of two parts are related to each other in orientation as mirror images across the interface known as the twinning plane.

VANADIUM – A rare metal used as an alloying element in steel to improve shock resistance and forgeability.

VULCANATES – Vulcanates are materials which reduce plasticity of the rubber compound, while maintaining its elasticity.

WHITE IRON – An extremely hard cast iron that results from pouring the hot metal into a mould with a chill plate in it.

WROUGHT IRON – Contains 1-2% slag, which is distributed through the iron as threads and fibres imparting a tough fibrous structure. Usually contains less than 0.1 % carbon. It is tough, malleable, and relatively soft.

WROUGHT METALS – These are metals furnished in the shapes resulting from the operations such as rolling, forging, drawing and extrusion.

YELLOW BRASS – An alloy of about 70% copper and 30% zinc.

ZINC – Bluish, grey metal with a melting point of 418°C, it becomes brittle at 200°C and can be powdered at this temperature.

ZIRCON – Natural zirconium silicate, containing when pure 67.3% zirconium oxide, and 32.7% silica, and is used as a moulding medium.