Glossary of Tube Terms

ACID BRITTLENESS - The brittleness induced in steel, especially wire or sheet, when it is pickled in dilute acid to remove scale, or during electroplating. Commonly attributed to absorption of hydrogen.

ACID STEEL - Steel made in a furnace or converter lined with siliceous (acid) refractory material. In the open hearth and electric furnaces employing the acid process, the hearth or bottom consists of fritted ("burned in") silica sand. The acid bessemer converter usually is lined with a kind of sandstone called "firestone." Raw materials for acid steel Must be low in phosphorus and sulfur.

ADDITIONS - Materials which are added to the molten bath of steel or to the molten steel in the ladle to produce the chemical composition required for the specific steel order.

AGING - The process by which steel changes in mechanical properties on long standing at ordinary room temperatures. Aging may change impact value, tensile strength, yield point, and behavior in certain forming operations.

AGE HARDENING - A process of aging that increases hardness and strength and ordinarily decreases ductility. Age hardening usually follows rapid cooling or cold working.

AIRCRAFT QUALITY - Denotes material for important or highly stressed palls. of aircraft and for other similar purposes; such materials are of extremely high quality requiring closely controlled, restrictive and special practices in their manufacture.

ALLOY - A substance that has metallic properties and is composed of two or more chemical elements of which at least one is a metal.

ALLOY SCRAP - Scrap steel which contains one or more alloying metals, such as nickel, chromium, tungsten, molybdenum. Such scrap must be very carefully classified according to ' composition and kept separate from other kinds of scrap.

ALLOY STEEL - "Steel is classified as alloy when the maximum of the range given for the content of alloying elements exceeds one or more of the following: manganese, 1.65 pet; silicon, 0.60 pet; copper, 0.60 pct; or in which a definite range or a definite minimum quantity of any of the following elements is specified or required within the limits of the recognized field of constructional alloy steels: aluminum, boron, chromium up to 3.99 pet, cobalt, columbium, molybdenum, nickel, titanium, tungsten, vanadium, zirconium, or any other alloying element added to obtain a desired alloying effect."

ALLOYING ELEMENTS - Chemical elements added for improving the properties of the finished products. Chief alloying elements in medium alloy steels are: nickel, chromium, manganese, molybdenum, vanadium, silicon, copper.

ALPHA IRON - The form of iron that is stable below Ac3 (1670°F., e.g., the temperature at which a change in phase occurs). See also Austenite, Ferrite and Gamma Iron.

ANNEALING - A process involving heating and cooling, usually applied to induce softening. The term also refers to treatments intended to alter mechanical or physical properties, produce a definite microstructure, or remove gases.

ANNEAL, DEOXIDIZING - A sub-critical anneal performed in an inert atmosphere in order to minimize oxidation, remove internal strains after cold reduction, decrease hardness and tensile strength and develop maximum ductility.

AUSTENITE - A solid solution formed when carbon and certain alloying elements dissolve in gamma iron. Gamma iron is formed when carbon or constructional alloy steel is heated above the so-called critical range, and the ferrite (alpha iron, with a body-centered crystal structure) is transformed to a face-centered crystal structure. Austenite does not exit in most ordinary steels at room temperature.

AUSTENITIZING - The process of forming austenite by heating a ferrous alloy to temperatures in the transformation range (partial austenitizing) or above the transformation range (complete austenitizing).

ANNEALING (FULL ANNEALING) - A softening process in which a ferrous alloy is heated to a temperature above the transformation range and after being held for a sufficient time at this temperature, is cooled slowly to a temperature below the transformation range. The alloy is ordinarily allowed to cool slowly in the furnace, although it may be removed and cooled in some medium that ensures a slow rate of cooling.

ANNEALING (PROCESS ANNEALING) - In the sheet and wire industries, a process by which a ferrous alloy is heated to a temperature close to, but below, the lower limit of the transformation range and is subsequently cooled. This process is applied in order to soften the alloy for further cold working.

ANNEALING (NORMALIZING) - A process in which a ferrous alloy is heated to a suitable temperature above the transformation range and is subsequently cooled in still air at room temperature.

ANNEALING (PATENTING) - Heating iron-base alloys above the critical temperature range followed by cooling to below that range in air or in molten lead maintained at a temperature of about 700°P.

ANNEALING (SPHEROIDIZING) - Any process of heating and cooling that produces a rounded or globular form of carbide in steel. Spheroidizing methods frequently used are:

            1. Prolonged holding at a temperature just below Ae1.

            2. Heating and cooling alternately between temperatures that are just above and j-List below Ae1.

            3. Heating to a temperature above Ae1 or Ae3 and then cooling very slowly in the furnace, or holding at a temperature just below Ae1.

            4. Cooling at a suitable rate from the minimum temperature at which all carbide is dissolved, to prevent the re-formation of a carbide network, and then reheating in accordance with method 1 or 2 above (applicable to hypereutectoid steel containing a carbide network).

ANNEALING (TEMPERING) - A process of reheating quench-hardened or normalized steel to a temperature below the transformation range, and then cooling at any rate desired.

ANNEALING (BRIGHT) - A process of annealing usually carried out in a controlled furnace atmosphere so that surface oxidation is reduced to a minimum and the surface remains relatively bright.

ANNEALING (MALLEABLIZING) - A process of annealing white cast iron in such a way that the combined carbon is wholly or partly transformed to graphitic or free carbon or, in some instances, part of the carbon is removed completely.

ANNEALING (GRAPHITIZING) - A heating and cooling process by which the combined carbon in cast iron or steel is transformed, wholly or partly, to graphitic or free carbon.

AUSTENITIC GRAIN SIZE - As used in this publication, is the grain structure established by a standardized heat treatment procedure.

AUSTENITIC STEEL - A steel in which the iron is in the gamma form at room temperature and which does not undergo thermal transformations in heating or cooling.

BALLISTIC TEST - A test in which a projectile is fired at an armor plate. The armor plate or the projectile (whichever one is being tested) must meet certain requirements.

BASIC MATERIAL - A chemical expression meaning the opposite of acid. Basic and acid materials, when brought together so that they can react, neutralize each other, forming salts or slags. In such reactions, the base becomes the positive part of the salt and the acid the negative. Examples of basic materials; limestone (or lime, CaO), magnesite (MgO), dolomite (containing both CaO and MgO). Examples of acid materials; quartzite or silica (SiO2) and the various clays, oxides of sulfur, etc. In metallurgy, the terms, "bases" and "acids," are applied to refractories, fluxes, and slags. Slags are said to be basic when the bases in them are greater than the acids; or to be acid when the acids in them are greater than the bases.

BASIC STEEL - Steel melted in a furnace that has a basic bottom and lining, and under a slag that is dominantly basic.

BASIC BOTTOM AND LINING - In a melting furnace, the inner lining and bottom composed of either crushed burned dolomite, magnesite, magnesite bricks or basic slag. These materials have a basic reaction in the melting process.

BANDED STRUCTURE - A segregated structure of nearly parallel bands aligned in the direction of working.

BEADING - Raising or depressing a ridge, of specified contour, on a section of tubing.

BEAM - An important member of the structural steel family. There are three varieties —the standard H, I, and wide flange used for the weight supporting purposes.

BEND RADIUS - The radius corresponding to the curvature of a bent specimen or bent area of a formed part, and measured on the inside of a bend.

BEND TESTS - Tests used to determine the ductility and/or other characteristics of tubing. The number of bends and the radius and degree of bends are generally determined by f the applicable specifications.

BENDING ROLLS - Three staggered rolls adjusted to put the desired curvature in plate or used for coiling and uncoiling strip or wire.

BESSEMER PROCESS - A process for making steel by blowing air under pressure through molten pig iron contained in suitable vessel, whereby a portion of the iron, most of the silicon and manganese and practically all the carbon are eliminated by oxidation. See Converter.

BLOWHOLE - An internal cavity in steel produced during the solidification of the metal by evolved gas which, in failing to escape, is held in pockets.

BLUE BRITTLENESS - Brittleness occurring in plain carbon steel when heated in the temperature range of 400° to 650° F., or when cold after being worked within this temperature range.

BLUE PLATE - Black plate the surface of which has been oxidized at a suitable temperature with steam or air to produce a blue color.

BOX ANNEALING - A process of annealing a ferrous alloy in a suitable closed metal container with or without packing material in order to minimize oxidation. The charge is usually heated slowly to a temperature below the transformation range, but sometimes above or within it, and is then cooled slowly. This process is also called "close annealing" or "pot annealing."

BRAZING - Joining metals by fusion of nonferrous alloys that have melting points above 800°F. but lower than those of the metals being joined. This may be accomplished by means of a torch (torch brazing), in a furnace (furnace brazing) or by dipping in a molten flux bath (dip or flux brazing). The filler metal is ordinarily in rod form in torch brazing; whereas in furnace and dip brazing the work material is first assembled and the filler metal may then be applied as wire, washers, clips, bands, or may be integrally bonded, as in brazing sheet.

BRAZING SHEET - A clad type of sheet product, coated on one or both surfaces with an alloy that has a melting point lower than the melting point of the core alloy. During brazing, only the coating melts and flows to form fillets in the preassembled article.

BRIGHT DIP - An acid solution into which articles are dipped to obtain a clean, bright surface.

BRITTLENESS - A tendency to fracture without appreciable deformation.

BULGING - Local expansion of tubes or shells by internal hydraulic pressure or by compression of a rubber cylinder.

BURNISHING - Plastic smearing such as may occur on metallic surfaces during buffing.

BURR - A rough or sharp edge left on metal by a cutting tool.

BUTT WELDING - Joining two edges or ends by placing one against the other and welding them.

CAMBER - A bend in a plate or other product of a rolling mill which results because one edge or side is longer than the other. Camber in plates is often caused by rolls which are closer together at one end than at the other, or by uneven temperatures in the slab. In rails and structural shapes, the camber is the "up or down" curvature, as distinguished from the sidewise curvature or "sweep."

CAMBER OF ROLLS - The increased diameter at the middle of rolls, designed to counter-balance the bending of the rolls when they are subjected to high pressures during rolling.

CAMBER OF SHEET - Curvature in the plane of rolled sheet or strip.

CAPPED STEEL - Capped steel, a variation of rimmed steel, is cast in a bottle top mold. The cap, placed in the neck of the mold soon after the mold has been filled to the proper level, stops the rimming action before it is completed by cooling the top metal. The product is an ingot having a thin rim relatively free of blowholes and with less segregation than is usual for a rimmed ingot of the same volume.

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

CARBONITRIDING - 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.

CARBON STEEL - Steel which owes its properties chiefly to various percentages of carbon without substantial amounts of other alloying elements; also known as straight carbon steel, or plain carbon steel. Steel is classified as carbon steel when no minimum content of elements other than carbon is specified or required to obtain a desired alloying effect; when the specified minimum for copper does not exceed 0.40 pet; or the maximum content for the following does not exceed the percentages noted: manganese, 1.65; silicon, 0.60; copper, 0.60.

CARBURIZING - To introduce carbon: (1) while steel is molten by adding carbonaceous material, coke, coal, electrode scrap, etc.; (2) while steel is in the solid state by heating it in contact with carbonaceous matter below its melting point.

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. Typical case-hardening processes are carburizing and quenching, cyaniding, carbonitriding, nitriding, induction hardening and flame hardening.

CHAMFER - To cut at an angle or bevel.

CIRCULAR WELD - Safe end weld. A weld extending around a girth seam. Such welds are sometimes butted, but frequently are scarfed.

CLADDING - A process for covering one metal with another. In tubing this is accomplished by placing one tube within a thin-walled cladding tube and drawing down the cladding tube until it is firmly fastened to the inner tube.

CHIPPING - A method for removing seams and other surface defects with chisel or gouge so that such defects will not be worked into the finished product. Chipping is often employed also to remove metal that is excessive but not defective. Removal of defects by gas cutting is known as ”deseaming" or "scarfing."

CHROME-CARBIDE PRECIPITATION - A chemical reaction sometimes occurring in chrome-nickel steel, in which the chromium, near the boundaries of the grains, flows to the boundaries and unites with carbon, thus forming the chrome carbides and depleting the chromium supply in the metal near the grain boundaries. This makes the steel susceptible to intergranular corrosion when brought into contact with various acids or alkalis.

CHROME PICKLE - A chemical treatment for magnesium in a nitric acid, sodium dichromate solution. The treatment gives some protection against corrosion by producing a film that is also a base for paint.

CHROMIUM - An alloying element added to alloy steel (in amounts up to around 1.50 pet) to increase hardenability. Chromium content of 5 pct or more confers special ability to resist corrosion. Steels containing more than 10.5 pet chromium are called "Stainless Steel."

COATING - The process of covering steel with another material, primarily for corrosion resistance.

COHESIVE STRENGTH - A term used with one of the following meanings:

            1. The maximum stress required in order to cause tensile fracture in the absence of any deformation, when two of the three principal stresses equal zero; that is, with a notched bar. Sometimes called "initial cohesive strength."

            2. The maximum principal stress required in order to cause tensile fracture when triaxial stresses are present; that is, by using a notched test bar. This is frequently called the "technical cohesive strength" and is variable, depending on the relative magnitude of the three principal stresses, the amount of plastic deformation preceding fracture, and the temperature and rate of straining.

COLD DRAWN - Refers to tubing drawn in the cold state through a hardened steel or carboloy die, either with or without a mandrel on the inside.


            1. A discontinuity that appears on the surface of cast metal as a result of two streams of liquid meeting and failing to unite. Pouring the metal when it is too cold may cause such a discontinuity.

            2. On a forging, a portion of the surface that is separated by oxide from the main body of metal.

COLD WORK  - Plastic deformation at such temperatures and rates that substantial increases occur in the strength and hardness of the metal. Visible structural changes include changes in grain shape and, in some instances, mechanical twinning or banding.

COLD HEADING  - Cold heading consists in forcing metal to flow cold into dies to form thicker sections and more or less intricate shapes. The operation is performed to specialized machines where the metal, in the form of wire or bar stock, may be upset or headed in certain sections to a larger size and, if desired, may be extruded in other sections to a smaller diameter than the stock wire. Although cold heading was developed for the production of bolts, screws, and rivets and is used largely for these parts, the process is applicable to a wide variety of special parts that have somewhat similar form.

COLD HEADING QUALITY - Produced by closely controlled steelmaking practices including special melting, rolling, conditioning, inspection and testing, in order to be defect free and satisfactory for cold heading.

COLD ROLLED PRODUCTS - Flat-rolled products which have been finished by rolling the piece without heating (at approximately room temperature).

COLD WORKING - Deforming a metal plastically at such a temperature and rate that strain hardening occurs. The upper limit of temperature for this process is the recrystallization temperature.

COLLAPSING PRESSURE - A pressure, which, when applied to the outside of a tube, causes it to cave in, or to fail by bending or buckling inwardly.

COMBINED CARBON - The carbon that is combined with iron or alloying elements to form carbide in cast iron or steel.

COLUMBIUM - A metal which may be added to chrome-nickel stainless steel to improve its welding qualities, by preventing carbide precipitation.

COMPRESSIVE TEST (TUBING) - Test made on a section of tube applying compressive force perpendicular to the axis of the tube.

CONCENTRICITY - AS reference to a tube, the center line of inside diameter is consistent with the center line of the outside diameter.

CONDUIT PIPE - Wrought pipe used as armor for electric wires.

CONSTANT-LOAD TEST - A stress-corrosion cracking or mechanical test in which the specimen is stressed by applying a dead load.

CONTROLLED COOLING - A process of cooling from an elevated temperature in a pre-determined manner, to avoid hardening, cracking or internal damage, or to produce a desired microstructure. This cooling usually follows the final hot forming operation.

COOLING STRESSES - Stresses developed by uneven contraction of external constraint of metal during cooling; also those stresses resulting from localized plastic deformation during cooling, and retained.


         1. A body of sand or other material placed in a mold to produce a cavity of desired shape in a casting.

         2. A tubular defect that comes from the surface of a billet and appears at the back end of extruded rod.

         3. The center or base portion of a clad product.

CORE - In a ferrous alloy, the interior portion that is substantially softer than the surface layer or case, after case hardening.

CORE LOSS - That part of the electrical energy required to magnetize a core of magnetic material that is dissipated as heat generated within the core, as distinguished from the energy lost in the coil surrounding the core.

CORROSION  - Gradual chemical or electrochemical attack on a metal by atmosphere, moisture or other agents.

CORROSION EMBRITTLEMENT - The embrittlement caused in certain alloys by exposure to a corrosive environment. Such material is usually susceptible to the intergranular type of corrosion attack.

CORROSION FATIGUE - The repeated cyclic stressing of a metal in a corrosive medium, resulting in more rapid deterioration of properties than would be encountered as a result of either cyclic stressing or of corrosion alone.

COUPLE - Two dissimilar conductors in electrical contact. An electromotive force is created under proper electrolytic influences or during heating.

COUPLING - A threaded sleeve used to connect two pipes. Commercial couplings are threaded inside to suit exterior thread of pipe.

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 STRENGTH - All stressed metals slowly deform at elevated temperatures even under stresses below their short-time yield points. This deformation is called "creep." The creep strength is determined by loading specimens maintained at high temperatures for 1000 hours or more, noting the deformation, and then calculating the stress in polands per square inch required to produce one per cent elongation in 10,000 or in 100,000 hours.

CREEP LIMIT - The maximum stress that will result in creep at a rate lower than an assigned rate.

CRITICAL STRAIN - The percentage strain at which, or immediately higher than which, large grain growth occurs during heating.

CROP - The end or ends of an ingot that contain the pipe or other defects to be cut off and discarded; also termed "crop end" and "discard."

CRUCIBLE - A ceramic pot or receptacle made of graphite and clay, or clay or other refractory material, used in the melting of metal.

CRUSHED TEST - Same as Compression Test.

CRYSTALLIZATION - The formation of crystals by the atoms assuming definite positions in a crystal lattice. This is what happens when a liquid metal solidifies. (Fatigue, the failure of metals under repeated stresses, is sometimes falsely attributed to crystallization.)

CUP FRACTURE - The type of fracture in which the exterior portion is extended and the interior is relatively depressed, resembling a cup. When only a part of the exterior is extended, the term "half-cupped" or "quarter-cupped" is used.

CYANIDING - A process of case hardening a ferrous alloy by heating in a molten cyanide, thus causing the alloy to absorb carbon and nitrogen simultaneously. Cyaniding is usually followed by quenching to produce a hard case.

DECAREURIZATION - The loss of carbon from the surface of a ferrous alloy as a result /Of heating in a medium that reacts with the carbon.

DEEP DRAWING - Forming shaped articles or shells by forcing sheet metal into a die.

DEEP ETCHING - Macro-etching; etching, for examination at a low magnification in a reagent that attacks the metal to a much greater extent than normal for microscopic examination. Gross features may be developed: Abnormal grain size segregation, cracks or grain flow.

DESCALING - The process of removing scale from the surface of steel. Scale forms most readily when the steel is hot by union of oxygen with iron. Common methods of descaling are:

         1. Crack the scale by use of roughened rolls and remove by a forceful water spray,

Throw salt or wet sand or wet burlap on the steel just previous to its passage through the rolls.

DRAWING QUALITY - Flat-rolled products produced from either deep drawing rimmed steel or extra deep drawing aluminum killed steels. Special rolling and processing operations aid in producing a product which can stand extreme pressing, drawing, or forming, etc., without creating defects.

DUCTILITY - The property that permits permanent deformation before fracture by stress in tension.


         O.D. : — Outside Diameter. Specified in inches and fractions of an inch, or in inches and decimals of an inch.

         I.D.: — Inside Diameter. Specified in same terms as the O.D.

            WALL: —Wall thickness or Gage. Specified in either fractions of an inch, decimals of an inch or by a "Wire Gage" number. In the United States the standard wire gage used for tubing is the "Birmingham" iron wire gage, designated "B.W.G."

DIRECT QUENCHING - A process of quenching carburized parts directly from the carburizing operation.

DIFFERENTIAL HEATING - A heating process by which the temperature is varied within the object so that, after cooling, various parts may have different properties as desired.

DIFFUSION ZONE - In the clad type of products, the zone between coating and core, in which diffusion between the two has occurred.

DRY CYANIDING - Synonymous with carbonitriding.

ELECTROCHEMICAL CORROSION - Localized corrosion that results from exposure of an assembly of dissimilar metals in contact or coupled with one another; or of a metal containing macroscopic or microscopic areas dissimilar in composition or structure. The dissimilar elements form short-circuited electrodes, the corrosive medium is the electrolyte, and an electric current is induced, which results in the dissolution of the electrode that has the more anodic solution potential, while the other is unattacked. The same condition may result from local differences within the corroding medium.

ELASTIC AFTEREFFECT - A slight contraction that occurs slowly while metal is standing with no load, subsequent to plastic tensile flow and immediate elastic recovery. Microscopic stresses, acting in compression, are responsible for this as well as for the Bauschinger effect.

ELASTIC CONSTANTS - In the general form of Hookes Law, the elastic moduli, which vary in individual crystals with the direction of test. ELASTIC DEFORMATION—Temporary

changes caused in dimensions by stress. The material returns to the original dimensions after removal of the stress.

ELASTIC HYSTERESIS - Energy absorbed by reversed deformation, represented by the closed loop of stress-strain curves in the elastic range, formed by curves for loading and unloading.

ELASTIC LIMIT - The maximum stress which a material is capable of sustaining without any measurable permanent extension remaining after complete release of the applied force.

ELONGATION - The amount of permanent extension in the vicinity of the fracture in the tension test; usually expressed as a percentage of the original gage length, as 25% in 2 in. Elongation may also refer to the amount of extension at any stage in any process that elongates a body continuously, as in rolling.

ENDURANCE LIMIT - The maximum Stress that a metal will withstand without failure during a specified large number of cycles of stress. If the term is employed without qualification, the cycles of stress are usually such as to produce complete reversal of flexural stress.

ENDURANCE RATIO - The ratio of the endurance limit for cycles of reversed flexural stress to the tensile strength.

EROSION - The abrasion of metal or other material by liquid or gas, usually accelerated by pressure of solid particles of matter in suspension, and sometimes by corrosion

ETCHING - In metallography, the process of revealing structural details by the preferential attack of reagents on a metal surface.

ETCH TESTS - Tests used to detect inclusions in steel. A common method of making the test is to dip the sample into acid which reacts with the inclusions and discloses their presence.

EXFOLIATION - A type of corrosion that progresses parallel to the outer surface of the

metal, causing layers of the metal to be elevated by the formation of corrosion product.

EXPLOSIVE RIVET - A type of blind fastener in which a hollow-shank rivet is used, containing an explosive charge. The rivet shank is expanded by exploding the charge after the rivet has been inserted.

EXTRUSION - Shaping metal into a chosen continuous form by forcing it through a die of appropriate shape.

FABRICATOR, STEEL - One who forms, manufactures or builds. His operations are to punch, cut, shear, drill, bend, flange or weld plates and shapes.

FATIGUE - The tendency for a metal to break under conditions of repeated cyclic stressing considerably below the ultimate tensile strength.

FATIGUE CRACK OR FAILURE - A fracture starting from a nucleus where there is an abnormal concentration of cyclic stress and propagating through the metal. The surface is smooth and frequently shows concentric (sea shell) markings with a nucleus as a center.

FATIGUE LIMIT - The maximum stress that a metal will withstand without failure for a specified large number of cycles of stress. Usually synonymous with endurance limit.


            1.) A characteristic of wrought metal that indicates directional properties and is revealed by the etching of a longitudinal section or is manifested by the fibrous or woody appearance of a fracture. Fiber is caused chiefly by the extension of the constituents of the metal, both metallic and nonmetallic, in the direction of working.

            2.) The pattern of preferred orientation of metal crystals after a given deformation process (usually wiredrawing).

FIBER STRESS - Local stress at a point OF line on a section over which stress is not uniform, such as on the cross section of a beam under a bending load.

FERRITE - A solid solution in which alpha iron is the solvent, and which is characterized
by a body-centered cubic crystal structure.
See also Austenite, Alpha Iron, Gamma Iron.

FERROALLOY - An iron-bearing product, not within the range of those called steels, which contains a considerable amount of one or more alloying elements, such as manganese, silicon, phosphorus, vanadium, chromium. Some of the more common ones are ferrochromium, ferromanganese, ferrophosphorus, ferrosilicon, ferrovanadium. The chief use of these alloys is for making additions of their respective alloying elements to molten steel.

FERROCHROME - A finishing material which contains about 70 pct chromium. It is used when it is desired to add chromium to steel.

FERROMANGANESE - A product of the blast furnace, containing, besides iron, 78 to 82 pct of manganese and some silicon, phosphorus, sulphur and carbon. It is used as a deoxidizer and for the introduction of manganese into steel.

FERROPHOSPHORUS - A finishing material (see "finishing") which contains about 18 pet phosphorus. It is used when it is necessary to add phosphorus to steel.

FERROSILICON - A product of the blast furnace which contains 8 to 15 pet silicon. It is used as a deoxidizer and for adding silicon to steel.

FERROUS METALLURGY - That section of general metallurgy which embraces the science and knowledge applying to iron and steel products, their preparation and adaptation to their numerous uses.

FERROVANADIUM - A product which contains iron and about 38 pct vanadium. Used as a finisher for adding vanadium to steel.

FINISH - In the steel industry, refers to the type of surface condition desired or existing in the finished product.

FINISHED STEEL - Steel that is ready for the market without further work or treatment. Blooms, billets, slabs, sheet bars, and wire rods are termed "semifinished."

FINISHING TEMPERATURE - The temperature at Which hot mechanical working of metal is completed.

FLAME ANNEALING - A process of softening a metal by the application of heat from a high-temperature flame.


            (1) Severing a piece of steel by burning a portion out by means of an oxyacetylene torch, or

            (2) removing a part of the surface by means of the burning torch, as in conditioning. (More properly called "scarfing.")

FLAME HARDENING - A process of hardening a ferrous alloy by heating it above the transformation range by means of a high-temperature flame, and then cooling as required.


            (1) A projection of metal on formed objects.

            (2) The parts of a channel at right angles to the central section or web.

FLARE TEST - A tapered expansion over a cone having various degrees and of various lengths.

FLASH - A thin fin of metal formed at the sides of a forging or weld when a small portion of metal is forced out between the edges of the forging or welding dies.

FLATTENING - Standard commercial flatness is obtained by roller leveling. This consists in passing sheets singly or in packs through a machine having a series of small diameter rolls.

FLATTENING TEST -  It is Customary to take a ring or crop end from the tube or pipe, position the weld either 0º or 90º to the applied force and flatten between paralleled plates, without cracking or showing flaws. Usually test specimens are flattened to 5 times the wall thickness.

FLOATING LOAD - A load carried on and attached to skids which are free to slide longitudinally under traffic shocks. Lateral movement is prevented by lumber fastened to the car floor.

FLOATING PLUG – A plug that locates itself inside a tube during drawing, in such a way that the tube is reduced in thickness between the plug and the die.

FLOW STRESS – The shear stress required to cause plastic deformation of solid metals.

FOG QUENCHING - A method of quenching in which a fine vapor or mist is used as the quenching medium.

FORMING - To shape or fashion with the hand or tools or by a shape or mold.

FORMING PROPERTIES - Those physical and mechanical properties that allow a steel to be formed without injury to the steel in the finished product.

FRACTURE STRESS - The maximum principal true stress (fracture load divided by fracture area.)

FRACTURE TEST - Breaking a piece of metal for the purpose of examining the fractured surface to determine the structure or carbon content of the metal or to detect the presence of internal defects.

FULL ANNEALING - A softening process in which a ferrous alloy is heated to a temperature above the transformation range and, after being held for a sufficient time at this temperature, is cooled slowly to a temperature below the transformation range. The alloy is ordinarily allowed to cool slowly in the furnace, although it may be removed and cooled in some medium that ensures a slow rate of cooling.

FUSION WELDING - A term which refers to the union of metals by fusion, using acetylene blow-pipe, electric current or the thermit reaction.

GAGES - A measurement of thickness. There are various standard gages such as United States Standard Gage (USS), Galvanized Sheet Gage (GSG), Birmingham Wire Gage (BWG).

GAGE, WORKING - The gage used by the workman in inspecting the product. Tested periodically by the reference gage.

GAS CYANIDING - Synonymous with carbonitriding.

GALVANIZING - The process of applying a coating of zinc to the finished tube. The coating is applied by hot dipping or electrolytic deposition.

GALVANNEALED - An extra tight coat of galvanizing metal (zinc) applied to a soft steel sheet, after which the sheet is passed through an oven at about 1200° F. The resulting coat is dull gray without spangle especially suited for subsequent painting.

GAS CUTTING - Cutting material with gas torch rather than by shearing. This operation may set up undesirable stresses in the material near the cut edges due to thermal effects; such stresses can be relieved by suitable heat treatment. Same as flame cutting.

GRAINS - Individual crystals in metals.

GRAIN SIZE - In many nonferrous metals, particularly alpha brasses, grain size is expressed in millimeters average diameter and is determined by comparison with standards as 75 diameters in magnification. The grain size may also be expressed in terms of the number of grains per unit area or volume.

GRAPHITIZING - A heating and cooling process by which the combined carbon in cast iron or steel is transformed, wholly or partly, to graphitic or free carbon.

HARDENABILITY - In a ferrous alloy, the property that determines the depth and distribution of hardness induced by quenching.

HAND TIGHT - Couplings tightened by hand with such effort as an average man can continuously exert. It does not refer to such forcings as can be done by a man picked for his strength.

HARDNESS - Defined in terms of the method of measurement.

            (1) Usually the resistance to indentation.

            (2) Stiffness of temper of wrought products.

            (3) Machinability characteristics.

HEAT TREATING FILM - A thin oxide coating or film formed on the surface of metals during thermal treatments.

HEAT TREATMENT - A combination of heating and cooling operation, timed and f applied to a metal or alloy in the solid state in a way that will produce desired properties. Heating for the sole purpose of hot working is excluded from the meaning of this definition.

HIGII STRENGTH STEEL - Low alloy steels forming a specific class in which enhanced mechanical properties and, in most cases, good resistance to atmospheric corrosion are obtained by the incorporation of moderate proportions of one or more alloying elements other than carbon. The preferred terminology is now "high-strength, low-alloy steels."

HOMOGENEOUS - Usually defined as having identical characteristics throughout. However, physical homogeneity may require only an identity of lattice type throughout while chemical homogeneity requires uniform distribution of alloying elements.

HOMOGENIZING TREATMENT - A heat treatment, usually for a long time at a high temperature, designed to make metal chemically homogeneous.

HOT FORMING - Working operations, such as bending and drawing sheet and plate, forging, pressing, and heading, performed on metal heated to temperatures above room temperature.

HOT SHORTNESS - Brittleness in hot metal.

HOT QUENCHING - A process of quenching in a medium at a temperature substantially higher than atmospheric temperature.

HOT WORKING – Plastic deformation of metal at such a temperature and rate that strain hardening does not occur. The lower limit of temperature for this process is the recrystallization temperature.

IMMERSION COATING – Coating a metal with a second metal by immersing the first in a solution containing ions of the second.

IMPACT EXTRUSION - A cold forming process in which the metal is forced by impact to flow around the punch, forming a tube with a solid bottom.

IMPACT TEST - A test to determine the energy absorbed in fracturing a test bar at high velocity. The test may be in tension or in bending, or it may properly be a notch test if a notch is present, creating multiaxial stresses.

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.

INDIRECT EXTRUSION (INVERTED) - An extrusion process in which the metal is forced back inside a hollow ram that pushes the die.

INDUCTION HARDENING - A process of hardening a ferrous alloy by heating it above the transformation range by means of electrical induction, and then cooling as required.

INDUCTION HEATING - A process of heating by electrical induction.

INITIAL CREEP - The early part of the time — elongation curve for creep, in which extrusion increases at a rapid rate.

INCLUSIONS - Particles of non-metallic impurities, usually oxides, sulphides, silicates, and such, which are mechanically held in steel during solidification.

INTERCRYSTALLINE CRACKING - Cracks of fractures that follow along grain boundaries in the microstructure of metals and alloys.

INTERANGULAR CORROSION - A type of electrochemical corrosion that progresses preferentially along the grain boundaries of an alloy, usually because the grain boundary regions contain material anodic to the central regions of the grain.

INTERNAL SOUNDNESS - Refers to condition of inside of material —lack of defects, pipe, segregation, non-uniformity of composition.

INTERRUPTED QUENCHING - A process of quenching in which the metal object being quenched is removed from the quenching medium while the object is at a temperature substantially higher than that of the quenching medium.

INTRACRYSTALLINE FAILURES - Fractures across the grains in metal.

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 ferrite-carbide aggregate.

KILLED, SEMI-KILLED, AND RIMMED STEEL - The factors governing steel ingot structures are influenced in degree or extent by various conditions singly or in combination, some of which are temperature and chemical composition of both metal and slag, rate of pouring, and size and shape of ingot molds. The control of such interrelated conditions has been the object of extended research and experimental work.

            The manufacture of steel from raw materials is an oxidizing process, and the molten metal as it comes from the furnace contains more or less oxygen in the form of dissolved oxides, the amount varying with the composition desired, and with certain conditions of steel making.

            If certain elements such as manganese, silicon or aluminum are added in sufficient amounts to molten metal in the furnace, in the ladle, or in the ingot mold, the metal will solidify quietly without evolution of gases.

KILLED STEEL - Steel deoxidized with a strong deoxidizing agent such as silicon or aluminum in order to reduce the oxygen content to a minimum so that no reaction occurs between carbon and oxygen during solidification.

LADLE ANALYSIS - The term applied to the chemical analysis representative of a heat blow of steel and is the analysis reported to the purchaser. It is determined by analyzing (for such elements as have been specified) a test ingot sample obtained from the first part or middle part of the heat or blow during the pouring of the steel from a ladle.

LAMINATIONS - Defects resulting from the presence of blisters, seams or foreign inclusions aligned parallel to the worked surface of a metal.

LAP - A surface defect appearing as a seam caused from folding over, during hot rolling, fins or sharp corners and then rolling or forging, but not welding, them into the surface.

LAP WELD - A term applied to a weld formed by lapping two pieces of metal and then pressing or hammering, and applied particularly to the longitudinal joint produced by a welding process for tubes or pipe, in which the edges of the skelp are beveled or scarfed so that when they are over-lapped they can be welded together.

LENGTHS - Tubular products are furnished

            (1) random lengths as produced on the mill,

            (2) in average lengths, falling between specified minimum and maximums,

            (3) in definite cut-lengths,

            (4) multiple lengths, each suitable for cutting into a definite number of short pieces, or

            (5) in welded double-lengths, meaning two lengths welded together, in order to produce desired long lengths.

LONGITUDINAL TEST - This term should be used only in connection with test specimens, both tension and bend, and to indicate that their longitudinal axis is parallel to the direction of greatest extension of the material from which they are cut. The stresses applied to both the tension and bend test specimens will be in the direction of their longitudinal axis. In speaking of bending flat-rolled products longitudinally, it is understood that the bend or fold runs parallel to the direction of greatest extension of the material in rolling (i.e., with the grain). This means, of course, that the direction of this bend is at right angles to the fold in a longitudinal bend specimen.

LONGITUDINAL DIRECTION - The direction in a wrought metal product parallel to the direction of working (drawing, extruding, rolling).

MACHINE STRAIGHTENING - The straightening of the material, which irregularities of the rolling and cooling often make necessary, is done in roll straighteners or machine straighteners, or by means of gag presses.

MACHINING - In general, the cutting away of the surface of a metal by means of power driven machinery. Specifically, a method of conditioning steel by machining away the surface. See Turning: Conditioning.

MACROETCH - A testing procedure for porosity, pipes, bursts, unsoundness, inclusions, segregations, carburization, flow lines from hot working, etc. Surface of the test piece should be reasonably smooth or even polished. After applying a suitable. etching solution, the structure developed by the action of the reagent may be observed.

MACROGRAPH - A photographic reproduction of any object that has not been magnified more than ten times.

MACROSCOPIC - Visible either with the naked eye or under low magnification (as great as about 10 diameters).

MACROSCOPIC DEEP ETCH TEST - Referred to as the porosity test. The test piece is heavily etched in HCI at 180 degrees F. and then closely examined under magnification for the detection of hammer bursts, pipe, seams, laps, checks, flakes. A light etch is employed to detect soft spots, depth of case, etc.

MACROSCOPIC STRESSES - Residual stresses of such scope that relatively large areas of the material or the whole specimen are involved. These stresses are accompanied by strain measurable with ordinary extensometers under appropriate test conditions.

MACROSTRUCTURE - The structure and internal condition of metals arc revealed on a ground or polished (and usually etched) sample, by either the naked eye or under low magnification (up to about 10 diameters).

MAGNAFLUX - An inspection given to important or highly stressed parts of aircraft quality steel using alloy. It consists in suitably magnetizing the material and applying a prepared magnetic powder which adheres to it along lines of flux leakage. It shows the existence of surface and subsurface nonuniformities.

MALLEABILITY - The property that determines the ease of deforming a metal when the metal is subjected to rolling or hammering. The more malleable metals can be hammered or rolled into thin sheet more easily than others.

MALLEABILIZING - A process of annealing white cast iron in such a way that the combined carbon is wholly or partly transformed to graphitic or free carbon or, in some instances, part of the carbon is removed completely.


            (1) A rod used to retain the cavity in hollow metal products during working.

            (2) A metal bar around which other metal may be cast, bent, formed or shaped.

MARTEMPERING - The process of quenching an austenitized ferrous alloy in a medium at a temperature in the upper portion of the temperature range of martensite formation, or slightly above that range, and holding in the medium until the temperature throughout the alloy is substantially uniform. The alloy is then allowed to cool in air through the temperature range of martensite formation.

MARTENSITE - An unstable constituent in quenched steel, formed without diffusion and only during cooling below a certain temperature. The structure is characterized by its acicular appearance on the surface of a polished and etched specimen. Martensite is the hardest of the transformation products of austentite. Tetragonality of the crystal structure is observed when the carbon content is greater than about 0.5 %.

MAXIMUM CORE LOSS - That part of the electrical energy required to magnetize a core of magnetic material that is dissipated as heat generated within the core, as distinguished from the energy lost in the coil surrounding the core. Core loss is made up of two components: hysteresis and eddy current losses.

MECHANICAL METALLURGY - The science concerned with the relationships among the measured mechanical properties of metals and their mechanical behavior in service, and with the way these properties and service characteristics vary with chemical composition, structure and temperature. The field also includes mechanical processing such as rolling, drawing and the like.

MECHANICAL PROPERTIES - Those properties of a material that reveal the elastic and inelastic reaction when force is applied, or that involve the relationship between stress and strain; for example, the modulus of elasticity, tensile strength and fatigue limit. These properties have often been designated as "physical properties," but the term "mechanical properties" is much to be preferred.

METALLURGY - The science which deals with the extraction of metals from their ores and the adaptation and application of these metals to the uses for which they are intended.

MECHANICAL TUBING - Used for a variety of mechanical and structural purposes as opposed to pressure tubing which is used for the conduction of fluids under pressure. It is commonly manufactured to consumer specifications covering chemical analysis, physical properties and often to special dimensional tolerances. It is used for such a variety of purposes that it is impractical to subdivide it into classifications such as are used for other classes of tubing.

MECHANICAL WORKING - Subjecting metal to pressure exerted by rolls, dies, presses, or hammers, to change its form or to affect the structure and consequently the mechanical and physical properties.

METALLOGRAPHY - The science concerning the constitution and structure of metals and alloys as revealed by the microscope.

MICROCLEANLINESS - Refers to the extent or quantity of nonmetallic inclusions observed by examination under a microscope.

MICROSCOPIC TESTS - Tests used in studying inclusions, segregation and structure. Microscopic studies may be supplemental and coordinated with other tests.

MILL FINISH - A surface finish produced on sheet and plate, characteristic of the ground finish on the rolls used in fabrication.

MILLING - The mechanical treatment of material, as in a ball mill, to produce particles or alter their size or shape, or to coat one component of a powder mixture with another.

MODULUS OF ELASTICITY - The slope of the elastic portion of the stress-strain curve in mechanical testing. The stress is divided by the unit elongation. The tensile or compressive elastic modulus is called "Young's modulus"; the torsional elastic modulus is known as the "shear modulus"; or "modulus of rigidity."

MODULUS OF RIGIDITY - In a torsion test, the ratio of the unit shear stress to the displacement caused by its per unit ,length in the elastic range. This modulus corresponds to the modulus of elasticity in the tension test.

MODULUS OF RUPTURE - The ultimate strength or the breaking load per unit area of a specimen tested in torsion or in bending (flexure). In tension, it is the tensile strength.

MOLYBDENUM - A special alloying element commonly used to increase hardenability

of steel. Molybdenum is sometimes added to stainless steel to enhance its corrosion resistance to certain chemicals. Molybdenum is commonly called "moly."

MOMENT OF INERTIA - It is not practical to provide an adequate definition of this term within the scope of this handbook. Reference to a recognized engineering handbook or textbook is suggested.

NECKING DOWN - The narrowing, or constricting to a smaller cross-sectional area, which occurs at a localized place on a tensile test piece while it is being pulled.

NITRIDING - A process of case hardening in which a ferrous alloy, usually of special composition, is heated in an atmosphere of ammonia or in contact with nitrogenous material to produce surface hardening by the absorption of nitrogen, without quenching.

NOMINAL SIZE - The diameter listed for the various sizes of pipe which, of course, is subject to variation either way as permitted in specification.

NORMALIZE - The normalizing process which is commonly applied to steel articles of heavy section consists of: heating to a temperature about 100° F. above the critical range and cooling in still air.

NOTCH BRITTLENESS - Susceptibility of a material to brittleness in areas containing a groove, scratch, sharp fillet or notch.

NOTCH SENSITIVITY - The reduction caused, in nominal strength, impact or static, by the presence of a stress concentration, usually expressed as the ratio of the notched to the unnotched strength.

OILED - Application of a suitable oil to final product to retard rusting. Where surface is a consideration, it is also desirable in reducing friction scratches that may develop in transit. The oil coating is not intended to serve as a lubricant for subsequent fabrication.

OXIDE - Usually refers in the steel industry to oxide of iron, of which there are three principal ones: FeO, Fe3O4, Fe2O3. In addition, there are many mixtures of these oxides which form on the surface of steel at different temperatures and give the steel different colors, such as yellow, brown, purple, blue and red. Oxides must be thoroughly removed from the surface of steel objects which are to be coated with tin, zinc, or other metals. See Scale.

OPERATING STRESS - The stress to which a structural unit is subjected during service.

OVALITY - The difference between the maximum and minimum diameters of any one section of tube.

OVERBENDING - Allowance for spring-back when bending metal to a desired angle.

OVERHEATED - A term applied when, after exposure to an excessively high temperature, a metal develops an undesirably coarse grain structure but is not permanently damaged. Unlike a burnt structure, the structure produced by overheating can be corrected by suitable heat treatment, by mechanical work, or by a combination of the two.

OVERSTRESSING - Permanently deforming a metal by subjecting it to stresses that exceed the elastic limit.

PACKAGE - A bundle or a number of bundles, secured into a single unit.

PACKAGING - Refers, in the steel industry, to most economical and safest method of grouping finished or semi-finished steel products for loading and transporting to the customer.


            1. Movement of a piece of steel through a stand of rolls.

            2. The open space between two grooved rolls through which is rolled the steel which is being processed.

PERMANENT SET - Inelastic deformation.


            1. Magnetic permeability, the ratio of the magnetic induction to the intensity of the magnetizing field.

            2. In a mold, the porosity of foundry sands and the ability of trapped gases to escape through the sand.

PHOTOMICROGRAPH – A photographic reproduction of any object magnified more than 10 diameters. The term micrograph may be used.

PHYSICAL PROPERTIES – Those properties familiarly discussed in physics, exclusive of those described under mechanical properties; for example, density, electrical conductivity, coefficient of thermal expansion. This term has often been used to describe mechanical properties, but this usage is not recommended. See mechanical properties.

PICKLE – Chemical or electrochemical removal of surface oxides.

PHYSICAL TESTING – Testing methods by which physical properties are determined. This term is also used inadvisedly to mean the determination of the mechanical properties.

PIPE – A cavity formed by contraction in metal (especially ingots) during solidification of the last portion of liquid metal.

PIT – A sharp depression in the surface of metal.

PLASTIC DEFORMATION – Permanent distortion of a material under the action of applied stresses.

PLASTICITY – The ability of a metal to be deformed extensively without rupture.

PLUG - A rod or mandrel that fills a tube as it is drawn through a die.

POROSITY –  Unsoundness caused in cast metals by the presence of blowh

Stay on top of all the news. Sign up for our newsletter.