glossary of material terms

8/4/2019 Glossary of Material Terms

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Glossary Of Mechanical Engineering Terms

This glossary contains industry-related definitions. As part of our customer-focusedcommitment, we are providing this glossary as an aid to better understanding ofCarpenter products and processes.

Acid Process - A process of making steel, either Bessemer, open-hearth, or electric, inwhich the furnace is lined with a siliceous refractory and for which low phosphorous pigiron is required as this element is not removed.

Age Hardening - The term as applied to soft or low carbon steels, relates to slow,gradual changes that take place in properties of steels after the final treatment. Thesechanges, which bring about a condition of increased hardness, elastic limit, and tensilestrength with a consequent loss in ductility, occur during the period in which the steel isat normal temperatures.

Aging - Spontaneous changes in the physical properties (for example, increase intensile strength and hardness) of some metals, which occur on standing at atmospherictemperatures after final cold working or after a final heat treatment. Frequentlysynonymous with the term Age-Hardening.

Air Cooling - Cooling of the heated metal, intermediate in rapidity between slowfurnace cooling and quenching, in which the metal is permitted to stand in the open air.

Air Hardening Steel - A steel containing sufficient carbon and other alloying elementsto harden fully during cooling in air or other gaseous mediums from a temperatureabove its transformation range. The term should be restricted to steels that arecapable of being hardened by cooling in air in fairly large sections, about 2 inches or

more in diameter.

AISI (American Iron and Steel Institute) - Steels of the American Iron and SteelInstitute. AISI is a North American trade association with 50 member companies andmore than 100 associate members. These companies represent the United States,Canada, and Mexico in all aspects of the steel industry. Common and alloy steels arenumbered in a system essentially the same as the SAE. The AISI system is moreelaborate than the SAE in that all numbers are proceeded by letters: A representsbasic open-hearth alloy steel, B acid Bessemer carbon steel, C basic open hearthcarbon steels, CB either acid Bessemer or basic open-hearth carbon steel, E electricfurnace alloy steel.

Alloy - A substance that has metallic properties and is composed of two or morechemical elements, of which at least one is metal.

Alloying Element - The adding of any metallic element in stainless steel production inorder to increase hardness, strength, or corrosion resistance. Molybdenum, nickel, andchromium are common alloying elements in stainless steel.


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Alloy Surcharge - The producers selling price plus a surcharge added to offset theincreasing costs of raw materials caused by increasing alloy prices.

Alpha In titanium, it is the hexagonally closed packed crystal structure that exists atlower temperatures.

Alpha Case The alpha-stabilized surface (oxygen-, nitrogen-, or carbon-enriched) ontitanium that results from elevated temperature exposure in an air furnace.

Angularity - The conformity to or deviation from specified angular dimensions in thecross section of a shape.

Annealing - A generic term denoting a heat treatment consisting of heating to andholding at a suitable temperature followed by cooling at a suitable rate, used primarilyto soften but also to simultaneously produce desired changes in other properties ormicrostructure.

Anodic Pro tection - Polarization to a more oxidizing potential to achieve a reducedcorrosion rate by the promotion of passivity.

AOD See Argon-Oxygen-Decarburization

Argon-Oxygen-Decarburization (AOD) - A steel refinement process by wherebycarbon is removed from molten steel through oxidation when a mixture of argon andoxygen is blown through the heat.

A.S.T.M. - American Society for Testing Material, an organization for issuing standardspecifications on material, including metals and alloys.

As Roll ed - The condition the material is in when it comes off the sizing rollers, coolingas its being processed. As rolled tends to result in hard spots and higher as-shippedhardness.

Austenite - Phase in certain steels, characterized as a solid solution, usually off carbonor iron carbide, in the gamma form of iron. Such steels are known as austenitic.

Austenite is stable only above 1333F (720C) in a plain carbon steel, but the presenceof certain alloying elements, such as nickel and manganese, stabilizes the austeniticform, even at normal temperatures.

Austen itic Steel - Steel which, because of the presence of alloying elements such as

manganese, nickel and chromium, shows stability of austenite at normal temperatures.Bar - Semi-finished or finished piece of metal in a straight length.

Bath Annealing - Immersion in a liquid bath (such as molten lead or fused salts) heldat an assigned temperature. When a lead bath is used, the process is known as leadannealing.


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Beam - Long pieces of squared-off metal, normally stainless steel, which are used inbuilding construction.

Bend Test - Various tests used to determine the toughness and ductility of flat rolledmetal sheet, strip or plate, in which the material is bent around its axis or around an

outside radius. A complete test might specify such a bend to be both with and againstthe direction of grain. For testing, samples should be edge filed to remove burrs andany edgewise cracks resulting from slitting or shearing. If a vice is to be used then linethe jaws with some soft metal or brass, so as to permit a free flow of the metal in thesample being tested.

Bessemer Process - A steelmaking process in which air is blown through the molteniron so that the impurities are thus removed by oxidation. Sir Henry Bessemer (1813-1898) was an English inventor who patented the first inexpensive industrial process forthe mass-production of steel from molten pig iron.

Beta In titanium, this body-centered cubic crystal structure exists at highertemperatures.

Billet - An ingot or bloom that has been reduced through rolling or hammering to anapproximate size of 2 to 7 inches square, or to an approximate rectangular crosssection of an equivalent area. Billets are classified as a semi-finished form of stainlesssteel that is used for long products such as bars and forgings.

Blank - A section of sheet stainless steel that has the outer dimensions of a specificpart but has not yet been stamped by the end user. This lowers stainless steelprocessor's labor and transportation costs.

Blast Furnace - A vertical shaft-type smelting furnace in which an air blast is used,usually hot, for producing pig iron. The furnace is continuous in operation using ironore, coke, and limestone as raw materials that are charged at the top while the molteniron and slag are collected at the bottom and are tapped out at intervals.

Blister - A raised spot on the surface of the metal caused by expansion of gas in asubsurface zone during thermal treatment.

Bloom - A semi-finished form of stainless steel that will be further processed into millproducts. A bloom generally has a cross section greater than 36 square inches.

Blooming Mill - A hot rolling mill that takes continuously cast slabs or ingots and

processes them into blooms.

Blowhole - A cavity produced during solidification of metal by evolved gas, which, infailing to escape, is held in pockets.

Brazing - Brazing and soldering are techniques for joining metals in the solid state bymeans of a fusible filler metal with a melting point well below that of the base metal.


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Bright Annealing - A process of annealing usually carried out in a controlledatmosphere so that the surface oxidation is reduced to a minimum and the surfaceremains relatively bright.

Bright Annealed Wire - Steel wire bright drawn and annealed in controlled, non-

oxidizing atmosphere furnace.Brinell Hardness Test - A common standard method of measuring the hardness ofcertain metals. The smooth surface of the metal is subjected to indentation by ahardened steel ball under pressure or load. The diameter of the resultant indentation inthe metal surface is measured by a special microscope and the Brinell hardness valueread from a chart or calculated formula.

Brittle Fracture - A fracture that has little or no plastic deformation.

Broken Surface - Surface fracturing, generally most pronounced at sharp corners, andminute cracks on the surface of a drawn product to the direction of drawing.

Burr -A subtle ridge on the edge of strip stainless steel resulting from cuttingoperations such as slitting, trimming, shearing, or blanking. For example, as a stainlesssteel processor trims the sides of the sheet stainless steel parallel or cuts a sheet ofstainless steel into strips, its edges bend with the direction of the cut. Furtherprocessing removes the burr.

Camber - Curvature of a straight plane. Not to be confused with a bow. Standardsteel industry tolerance for camber is 1/8 inch in 5 feet.

Carbon Steel - Common or ordinary steel as contrasted with special or alloy steels,which contain other alloying metals in addition to the usual constituents of steel in theircommon percentages.

Carburizing - The oldest method of case hardening in which carbon is added to thesurface of iron-base alloys by absorption through heating the metal at a temperaturebelow its melting point, in contact with carbonaceous solids, liquids or gases.

Case Hardening - Hardening a ferrous alloy to make the outside (case) much harderthan the inside (core). This can be done by carburizing, cyaniding, nitriding, carbonnitriding, induction hardening or flame hardening. Their application to stainless steel islimited wherever they decrease corrosion resistance.

Casting - To shape molten metal by pouring into a mold to produce an ingot or acontinuously cast slab.

Cast Steel - Any object made by pouring molten steel into molds.

Cathodic Corrosion - Corrosion caused by a reaction of an amphoteric metal with thealkaline products of electrolysis.


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Cathodic Inhibitor - A chemical substance that prevents or slows a cathodic orreduction reaction.

Cathodic Protection - Reducing the corrosion of a metal by making the particularsurface a cathode of an electrochemical cell.

Cavitation - The rapid formation and depletion of air bubbles that can damage thematerial at the solid/liquid interface under conditions of severe turbulent flow.

Cellular Manufacturing - A manufacturing philosophy that puts related processestogether to make a finished component in a continuous flow, as opposed to a series ofbatch operations.

Centerless Grinding - An operation whereby the surface of a bar is ground withoutusing a lathe.

Chemical Analysis - A report of the chemical composition of the elements and their

percentage that form a metal alloy.

Charge - The material that is loaded into an electric furnace that will melt into acomposition that will produce a stainless molten product. Normally recycled are scrap,iron and alloying elements.

Charpy Test - A notched-bar or impact test in which a notched specimen, fixed at bothends, is struck behind the notch by a striker carried on a pendulum. This test is used todetermine the pounds of pressure required to break the sample.

Chatter - An uneven surface on drawn products usually formed by vibration of themetal during drawing.

Chloride Stress Corrosion Cracking - Cracking due to the combination of tensilestress and corrosion in the presence of water and chlorides.

Chromium (Cr) - An alloying element that is used in stainless steel to deter corrosion.It is of bright silvery color and is relatively hard. It is strongly resistant to atmosphericand other oxidation. Its principal functions as an alloy in steel making include: (1)increased resistance to corrosion and oxidation; (2) increased hardenability; (3)additional strength at high temperatures; (4) resistance to abrasion and wear (with highcarbon).

Chromium Nickel Steel - Steel usually made by the electric furnace process in whichchromium and nickel participate as alloying elements. The stainless steel of 18%chromium and 8% nickel are the better known of the chromium-nickel types.

Cladding - Application of a stainless steel coating to a lower-alloy steel by means ofpouring, welding, or coating to increase corrosion resistance at a lower cost than usingsteel exclusively.

Coil Products - Products that are wound into a spiral of concentric rings.


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Cold Draw ing - The process of passing unheated steel through dies for the purpose ofreducing its cross-sectional area, imparting to it a particular shape.

Cold Finished Bars - Hot rolled stainless steel bars that are annealed and cold workedto produce a higher surface quality and higher strength. The term cold finished is an

umbrella definition for any material that has had some sort of surface treatment. Forexample, cold drawn, centerless ground, and smooth turned bar are cold finished.

Cold Forming (Cold Working) - Any mechanical operation that creates permanentdeformation, such as bending, rolling, drawing, etc., performed at room temperaturethat increases the hardness and strength of the stainless steel.

Cold Heading - Process of forcing metal to flow cold into dies to form thicker sectionsand more intricate shapes.

Cold Reduction - Reduction of metal size, usually by rolling or drawing, particularlythickness, while the metal is maintained at room temperature or below the

recrystallization temperature.

Cold-Rolled Strip (Sheet) - Stainless steel that has been run through a coldreduction mill. Sheet is under 3/16th of an inch and 24 inches wide and over. Strip isunder 3/16 of an inch and under 24" wide.

Cold Rolling - The process of passing unheated steel through pairs of driven rolls forthe purpose of reducing its thickness.

Cold Working - Any permanent deformation of unheated steel accomplished by theapplication of mechanical forces to the metal surface.

Concentricity - Center to end of the circle. All round bars have three tolerances toconsider: size, straightness, and out of round. The out of round tolerance couldaffect the concentricity of a bar.

Constituent - A necessary part or element; component.

Consumet - Carpenters trade name for consumable electrode vacuum melt.

Continuous Casting (strand casting) - A steel-forming process whereby moltenmetal is solidified into a semi-finished(hyphenate) billet, bloom, or slab for subsequentrolling in the finishing mills.

Continuous Furnace - Furnace, in which the material being heated moves steadilythrough the furnace.

Converter/ Processor - Stainless steel customers demanding stainless steel in a morefinished state such as tubing, pipe, and cold-rolled strip from re-rollers and tubemakers.


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

Corrosion Fatigue - Cracking due to repeating and fluctuating stresses in a corrosiveenvironment.

Corrosion Potential - The potential of a corroding surface in an electrolyte relative toa reference electrode under open-circuit conditions.

Corrosion Resistance - A metal's ability to resist corrosion in a particularenvironment.

Creep - Strain caused by the stress that occurs over time. Slow, permanentdeformation in a metallic specimen produced by a relatively small steady force belowthe elastic limit, acting for a long period of time.

Crevice Corrosion - Corrosion of stainless steel on the surface that is fully shielded

from air, preventing the formation of a passive film.

Critical Pitting Potential - The lowest value of oxidizing potential at which pits canform and grow. The value depends on the test method used.

Critical Range - A temperature range in which an internal change takes place within ametal. Also referred to as transformation range.

Crucible - A ceramic pot or receptacle made of graphite and clay, or clay or otherrefractory material, and used in the melting of metal. The term is sometimes applied topots made of cast iron, cast steel, or wrought steel.

Cut-to-Length - Cutting flat-rolled stainless steel into desired length and thennormally shipped flat-stacked.

Deburring - Removing the subtle ridge from the edge of strip metal that results fromcutting operation such as slitting, trimming, shearing, or blanking.

Decarburization - Removal of carbon from the outer surface of iron or steel, usuallyby heating in an oxidizing or reducing atmosphere. Water vapor, oxygen and carbondioxide are strong decarburizers. Reheating with adhering scale is also stronglydecarburizing in action.

Degassing Process - In steel making, removing gases from the molten metal by

means of a vacuum process in combination with mechanical action.

Descaling - A process that removes the oxide scale from the surface of the stainlesssteel, which develops from hot operations such as forging.

Drawing (Drawn) - The process of pulling material through a die to reduce the size,change the cross sectional shape, or harden the material. A forming process thatpresses metal into or through a die (as in cold drawn wire).


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Drawing Back - Reheating after hardening to a temperature below critical for thepurpose of changing the hardness of the steel (see tempering).

Drawn -Over-Mandrel - To produce specialty tubing, this procedure uses a drawbench to pull tubing through a die and over a mandrel, allowing excellent control of the

inside diameter and wall thickness.Drill Rod - A term given to an annealed and polished high-carbon tool steel rod,usually round and centerless ground. Drill rods are used principally by machinists andtool and die makers for punches, drills, taps, dowel pins, screw machine parts, smalltools, etc.

Ductil ity - The property that enables metals to be mechanically deformed when coldwithout fracturing. In steel, ductility is usually measured by elongation, and reductionof area is determined in a tensile test. A measurement of the malleability of stainlesssteel in terms of the amount of deformation it will withstand before failure.

Duplex - Stainless steel comprised of austenitic and ferritic stainless steels that containhigh amounts of chromium and nickel. This combination is stronger than both of theindividual stainless steels. Duplex stainless steels are highly resistant to corrosion andcracking.

Edge Rolling (Edge Conditioning) - To facilitate customer manipulation, strips ofstainless steel are rolled to smooth the edges and remove any burrs.

Elastic Springback - When stainless steel is bent, the metal towards the outside ofthe bend is in tension and the metal towards the inside is in compression. If the appliedbending force is not sufficient to cause permanent plastic flow at either the inner or

outer surfaces, the metal will return elastically to its original shape. Stainless steel has agreater elastic spring back than mild steel.

Electric Arc Furnace (EAF) - Melt-down unit which uses the heat of resistance to anelectric arc to perform the initial melting of steel.

Electric Furnace Steel - Steel produced in any furnace where heat is generatedelectrically, almost always by arc.

Electrode - An alloy cast into a preliminary shape for later remelting.

Electro-Slag Remelting (ESR) - A refining process which uses the heat of resistance

of molten slag to an electric arc to remelt an electrode in open atmosphere. ESRresults in metals of higher purity, more uniform grain size and improved mechanicalproperties.

Elongation - Increase in length which occurs before a metal is fractured, whensubjected to stress. This is usually expressed as a percentage of the original length andis a measure of the ductility of the metal.


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Embrittlement - Loss of malleability of a metal due to chemical treatment or physicalchange.

Engineered Product - Custom components that can be made from a wide range ofmaterial including advanced ceramics, carbides, specialty alloys or other specialty

materials.Erosion - The continuous depletion of a material due to mechanical interaction with aliquid, a multi-component fluid, or solid particles carried with the fluid.

Erosion-Corrosion - An accelerated loss of material concerning corrosion and erosionthat results from corrosive material interacting with the material.

ESR See Electro-Slag Remelting

Extrusion - A shaped piece of stainless steel produced by forcing the bloom, bar orrod through a die of the appropriate shape.

Fabricator - An intermediate product producer that purchases and processes materialfor a specific project.

Fatigue - The phenomenon leading to fracture under repeated or fluctuating stress.Fatigue fractures are progressive, beginning as minute cracks, and grow under theaction of fluctuating stress.

Ferrite - The body-centered cubic crystalline phase of iron-based alloys.

Ferrit ic Stainless Steel - Has a body centered cubic (BCC) structure. These alloys arethe chromium stainless steels containing low carbon levels. They are hardenable

primarily by cold working, although some will harden slightly by heat treating. Ferriticstainless steels work harden much slower than austenitic stainless steels.

Ferroalloy - 1. Metal products such as ferrochrome, ferromanganese, and ferrosiliconthat are commonly used as raw materials to aid various stages in stainless steelproduction. 2. An alloy of iron with a sufficient amount of some element or elementssuch as manganese, chromium, or vanadium as a means of adding these elements intomolten metal.

Ferrochrome - A common raw material in stainless steel production. This alloyconsists of iron and up to 72% chromium.

Ferrous - Related to iron (derived from the Latin ferrum). Ferrous alloys are,therefore, iron-base alloys.

Fine Grain Steel - Steels that resist grain growth over a considerable temperaturerange, when held at temperature for a reasonable length of time as is customary inheat treatment of steel.


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Finishes - The surface appearance of metals after final treatment such as rolling orpolishing.

Finishing Facilit ies - These facilities process semi-finished stainless steel into ready-made forms that can be used by others. Some facilities are rolling mills, pickle lines,

tandem mills, annealing facilities, and temper mills.Flat-Rolled Stainless Steel (Flat Product) - Category of stainless steel that includesshapes such as sheet, strip, and plate.

Flat Wire - A flat Cold Rolled, prepared edge section up to 1/4 wide, rectangular inshape. Generally produced from hot rolled rods or specially prepared round wire by oneor more cold rolling operations, primarily for the purpose of obtaining the size andsection desired. May also be produced by slitting cold rolled flat metal to the desiredwidth, followed by edge dressing.

Flux - An iron-cleaning agent that consists of limestone and lime. These products react

with impurities in the metallic pool and float to the top of the liquid iron.

Foil - Metal with a maximum width of 0.005 inches.

Forging - A form of hot working whereby metal is heated and formed into a desirableshape by pressing or hammering.

Forging Press - Type of hot working in which metal is heated until workable and thenpressed into the desired shape by compressing it between a pair of dies.

Forming - A process that brings about a change in the shape of stainless steel by theapplication of force (i.e. cold forming, hot forming, wire forming).

Fouling - An accumulation of marine organism deposits on a submerged metal surface.

Fracture Test - A test for carbon in which a specimen of metal is drawn off, cooledrapidly in water, and broken with a sledge hammer. The appearance of the metalexposed in the fracture permits a fairly accurate estimate of carbon content or thepresence of internal defects.

Free Machining - Grades of stainless steel that, by virtue of their chemistry orprocessing, are easier to machine into parts.

Frequency and severity - Rating for inclusions and stringers as allowed per each

individual grade specification. The quantity of inclusions per square inch equals thefrequency. The length of the inclusions per square inch is the severity. The ideal F/Srating would be 0/0. Each grade of steel has its own F/S.

Fretting Corrosion - Deterioration at the interface of two contacting surfaces underload that is accelerated by their relative motion.


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Full Annealing - Heating iron-based alloys above the critical temperature range,holding the temperature above that range for a proper period of time, and then slowlycooling to below the range either in the furnace or in a thermal insulating material.

Galvanic Corrosion - Accelerated corrosion of a metal because of an electrical contact

with a more noble metal or nonmetallic conductor in a corrosive electrolyte.Galvanizing - Coating steel with zinc and tin (principally zinc) for rust proofingpurposes.

Gas Carburizing - A method of carburizing carried out in an atmosphere of carburizinggases, including carbon monoxide and hydrocarbons as butane, ethane, methane, andpropane.

Gauer Bar - (see edge rolling)

Gauge - Thickness.

General Corrosion - "General corrosion" describes the attack that proceeds in arelatively uniform manner over the entire surface of a metal. Typically, stainless steelsdo not exhibit general corrosion.

Grade - The divisions within different types of steel based on carbon content ormechanical properties.

Grain - The individual crystal units in metals. A solid polyhedral (or many sidedcrystal) consisting of groups of atoms bound together in a regular geometric pattern.In mill practice grains are usually studied only as they appear in one plane:(1) (Direction of) refers to grain fiber following the direction of rolling and parallel to

edges of strip or sheets.(2) to bend across the grain is to bend at right angles to the direction of rolling.(3) to bend with the grain is to bend parallel to the directions of the rolling.In steel, the ductility in the direction of rolling is almost always twice that at rightangles to the direction of rolling.Grain is the individual crystal units comprising the aggregate structure where thecrystalline orientation does not change. The grain boundary is where these individualcrystal units meet.

Grain Boundary - Bounding surface between crystals. When alloys yield new phases(as in cooling) grain boundaries are the preferred location for the appearance of the

new phase. Certain deterioration such as season cracking and caustic embrittlement,occur almost exclusively at grain boundaries.

Grain Grow th - An increase in the average grain size; resulting from some crystalsabsorbing adjacent ones when the metal is raised to a temperature above thatnecessary for re-crystallization and kept at that temperature for a sufficient length oftime.


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Grain Size - The average grain diameter from a random cross-section of material.Grain size is an important property for many alloys, including the titanium commerciallypure alloys.

Grinding - A term that implies metal removal similar to fast milling in which the

surface is removed by abrasion.H-Steels - Steels made under specifications that include hardenability tolerance.

HARP - An abbreviation for "hot rolled annealed and pickled."

Hardenability - The ability of a metal, usually steel, to harden in depth asdistinguished from the term hardness.

Hardness - A measure of a steel's resistance to indentation: stiffness.

Hardness Test - Hardness testing consists of pressing an indenter into a flat surfaceunder a perfectly controlled load, then measuring the dimension of the resultingindentation. The three methods most commonly used for stainless steel are theRockwell B, Rockwell C and Vickers tests. The higher the number, the harder thematerial.

Heat - Term referring to batch of refined stainless steel; a charged oxygen or electricfurnace full of stainless steel. A heat of stainless steel can be used to cast several slabs,billets, or blooms.

Heat-Affected Zone (HAZ) - The part of a metal that is not melted during cutting,brazing, or welding, but whose microstructure and physical properties are altered bythese processes.

Heat Treatment - Altering the properties of stainless steel by subjecting it to a seriesof temperature changes. To increase the hardness, strength, or ductility of stainlesssteel so that it is suitable for additional applications.

High Temperature Alloy (superalloy) - Alloy that can withstand very hot operatingenvironments up to 2000F (1093C) for some alloys and attendant corrosion andoxidation problems.

Hot Band (Hot-Rolled Stainless Steel) - Stainless steel that has been rolled on ahot-strip mill. It can be sold directly to customers or further processed into other

finished products.Hot Forming - Hot forming operations are used widely in the fabrication of stainlesssteel to take advantage of their lower resistance to shape change. High temperaturereduces their yield strengths, and this results in a marked lowering of the force that isrequired to bring about plastic movement or flow from one shape to another. (hotrolling, hot stretching, etc.)


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Hot Rolling - A method of hot working that reduces the cross-sectional size of a metalbar or coil by passing it between a series of rolls while the material is hot.

Hot Working - The permanent deformation of metal accomplished by applyingmechanical forces to the heated metals surface.

Hydrogen Embrittlement - The absorption of hydrogen by a metal resulting in a lossof ductility.

Hydrogen-Induced Cracking - Stepwise internal cracks that connect adjacenthydrogen blisters on different planes in the metal, or to the metal surface.

Hydrogen Stress Cracking - Cracking of a metal resulting from the combination ofhydrogen and tensile stress.

Impact Test - Impact testing is used to measure the toughness of a material,corresponding to the energy necessary to cause fracture under shock loading. Low

toughness is generally associated with brittle shear fracture and high toughness withductile plastic tearing.

Ingot - An initial cast form that results from a molten alloy being poured into an ingotmold. Remelted alloys also are called ingots.

Injection Molding - A part-forming process in which metallic or ceramic powders,mixed with a binder, are pushed into a custom mold to make intricate parts. The partsmay have irregular features on all three axes.

Integrated Mills - Facilities that combine all the stainless steel making facilities frommelt shop through hot rolling and cold finishing, to produce mill products.

Intergranular Corrosion - Preferential corrosion cracking at or along the grainboundaries of a metal.

Intergranular Stress Corrosion Cracking - Stress corrosion cracking in which thecracking occurs along grain boundaries.

Iron Ore - A mineral that contains enough iron to be a factor in stainless steelproduction.

Iron-Based Superalloys - These alloys are at the highest end of the range oftemperature and strength. Additives such as chrome, nickel, titanium, manganese,

molybdenum, vanadium, silicon, and carbon may be used. These superalloys are alsoreferred to as super chrome stainless steels.

Leveling Line - A machine that smoothes any physical deficiencies in the sheet beforeit is shipped to the customer.

Life Cycle Costing - An accounting method of costing where expenses are allocatedover the life of the product. Life cycle costs are often lower for stainless steel than for


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alternatives despite a higher initial outlay, because stainless products generally lastlonger and require little maintenance.

Light-Gauge Stainless Steel - A very thin sheet of stainless steel that has eitherbeen temper rolled or passed through a cold reduction mill.

Line Pipe - A pipe extending over long distances that transports oil, natural gas, andother fluids.

Long Product - Product made into bar, rod, wire or billet, rather than a flat form.

Low Carbon Steels - Contain from 0.10% to 0.30% carbon and less than 0.60%manganese. The product of basic oxygen, Bessemer, open hearth or electric processes.

Machining - The cutting away of the surface of metal by means of power-drivenmachinery. Free-machining stainless steels are easier to machine, extending tool lifeand improving throughput.

Magnetic Alloys - Alloys that have special magnetic properties.

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

Martensite - A hard supersaturated solid solution of iron characterized by an acicular(needle-like) microstructure.

Martensitic Stainless Steel - Has a body centered tetragonal (BCT) structure. Thesealloys are chromium stainless steels with medium to high carbon levels. They work

harden slowly in the annealed (soft) condition but can be heat-treated to very hightensile strengths.

Mechanical Properties Those properties that reveal the reaction, either elastic orplastic, of a metal to an applied stress. Tensile strength, yield strength, elongation,reduction of area, hardness, impact strength, and bendability are mechanicalproperties.

Metal matrix Composite - Formed by infiltrating a ceramic preform with a moltenmetallic product. Once solidified, the resulting product combines the best features ofceramics and metals.

Melt ing Range - The range of temperature in which an alloy melts is the rangebetween solidus and liquidus temperatures.

Mill form - Shapes manufactured by traditional rolling or drawing operations, such asrounds, squares, hexagons and rectangles.

Mill Products - Generally mill forms of sheet, strip, plate, bar rod and semi-finishedforms.


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Modulus of Rigidity - Of a material suffering shear, the ratio of the intensity of theshear stress across the section to the shear strain, i.e., to the angle of distortion inradians; expressed in pounds or tons per square inch.

Molybdenum (Mo) - An alloying element that enhances corrosion resistance along

with chromium in stainless steels.Nickel (Ni) - An alloying element used in stainless steels to enhance ductility andcorrosion resistance.

Nickel-Based Superalloys - Alloy metal produced for high-performance, high-temperature applications such as nickel-iron-chrome alloys and nickel-chrome-ironalloys.

Nonferrous Metals - Non-iron based metal, including copper, aluminum and theiralloys (e.g., brass and bronze).

Oil Country Tubular Goods (OCTG) - Category of pipe products used by petroleumexploration customers. Labels bearing OCTG are applied to casting, drill pipes, oil welltubing, etc.

Ore - An iron-containing material used primarily in the melting furnace.

Oscillating - A method of winding a narrow strip of stainless steel over a much widerroll. This allows for more stainless steel per roll and allows the customer to have longerprocessing runs.

Oxidation - Rust or corrosion due to exposure to oxygen.

Passivation - When exposed in air, stainless steels passivate naturally (due to thepresence of chromium). But the time required can vary. In order to ensure that thepassive layer reforms rapidly after pickling, a passivation treatment is performed using asolution of nitric acid and water.

Passive - A characteristic condition of stainless steels which impedes normal corrosiontendencies to the point where the metal remains virtually un-attacked hence passiveto its environment.

Physical Properties - Those properties familiarly discussed in physics, exclusive ofthose described under mechanical properties; for example, density, electrical

conductivity, co-efficient of thermal expansion. This term often has been used todescribe mechanical properties, but this usage is not recommended (see MechanicalProperties).

Pickling or chemical mill ing A process that removes surface scale and oxidationproducts by immersion in a chemically active solution, such as sulfuric or hydrochloricacid. Used in titanium to help remove alpha case and/or surface imperfections.


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Pickling Paste - A commercially available product that performs the pickling functionwhen used on the surface of stainless steel.

Pipe - Term that originally defined a tube used to transport fluids or gases. Often now,pipe and tube are used interchangeably.

Pitting - Localized corrosion (in the form of pits) of a metal surface that is confined toa small area.

Plate - Product form in which the metal measures more than 10 inches wide and 3/16in. thick or more.

Postw eld Heat Treatment - Heating and cooling a weldment in such a way as toobtain desired properties.

Powder Al loys/ Powder Metals - Produced by means of a high-pressure gas to breakup a molten metal stream into droplets, which rapidly solidify into metal powder

particles. These particles are then consolidated to create bar, coil or other mill forms.Powder metal mill forms offer superior performance and uniformity to cast or wroughtmill forms.

Powder Metal lurgy - The art of producing metal powders and of utilizing metalpowders for the production of massive materials and shaped objects.

Precipitation Hardening (PH) - A small category of stainless steels resemblingmartensitic stainless steels that have great strength and hardness due to heattreatment.

Premium M elt ing or Vacuum M elt ing - A process in which raw materials are first

melted within a vacuum. The metal is often remelted again under a vacuum to producevery pure alloys. Together, these processes result in tighter control of a metalschemistry and greater consistency in structural properties such as toughness, ductility,and fatigue strength.

Process Annealing - In the sheet and wire industries, a process by which a ferrousalloy is heated to a temperature close to, but below, the lower limit of thetransformation range and is subsequently cooled. This process is applied in order tosoften the alloy for further cold working.

Quenching - In the heat treating of metals, the step of cooling metals rapidly in order

to obtain desired properties; most commonly accomplished by immersing the metal inoil or water. In the case of most copper base alloys, quenching has no effect other thanto hasten cooling.

Quench Hardening (Steel) - A process of hardening a ferrous alloy of suitablecomposition by heating within or above the transformation range and cooling at a ratesufficient to increase the hardness substantially. The process usually involves theformation of martensite.


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Reinforcing Bar (Rebar) - A commodity-grade stainless steel used to reinforceconcrete in highway and building structures.

Remelt ing - The process whereby previously melted electrodes are remelted intohigher quality ingot.

Residuals - The impurities remaining in mini-mill stainless steels resulting from thewide variety of metals entering the process.

Reversing Mill - A stand of rolls that passes stainless steel back and forth betweenthe rolls in order to reduce the stainless steel sheet or plate. The distance between therolls is reduced after each pass.

Rockw ell Hardness (Test) - A standard method for measuring the hardness ofmetals. The hardness is expressed as a number related to the depth of residualpenetration of a steel ball or diamond cone (brale) after a minor load of 10 kilogramshas been applied to hold the penetrator in position. This residual penetration is

automatically registered on a dial when the major load is removed from the penetrator.Various dial readings combined with different major loads, give scales designated byletters varying from A to H; the B and C scales are most commonly in use.

Rod - Semi-finished product, formed into coils, from which wire is made.

Scale (Scale Removal) - The oxide that forms on the surface of stainless steel, afterexposure to high temperature.

Seamless Pipe - Pipe produced from a solid billet that is heated and rotated underpressure. This rotating pressure creates a hole in the middle of the billet, which is thenformed into a pipe by a mandrel.

Semi-Finished Stainless Steel - Stainless steel products such as blooms, billets, orslabs that are then rolled and processed into beams, bars, wire, etc.

Sensitization - The phenomenon in austenitic stainless steels that causes a change tooccur in the grain boundaries when heated in the general range of 850 to 1475 degreesF. This change destroys the passivity in these locations.

Service Center - An operation that buys metal, stores it (often processing it in someway), and then sells it in a slightly different form than it was purchased from theproducing mills.

Shapes - Bar or coil product that is passed between custom dies and rolls to form half-round, hexagonal, square and other more intricate shapes.

Shape Correcting - Levelers, edge trimmers, and temper mills reshape processedstainless steel to meet customers specifications. Reshaping is needed from processesthat cause deformities in the stainless steel.

Shearing - Trimming of sheet strip to make the edges parallel.


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Sheet - A stainless steel flat rolled product that is under 3/16 inch in thickness and 24inches or more in width.

Shot Blasting - Blast cleaning using stainless steel shot as the abrasive. Notrecommended for stainless steel. Glass beads should be used.

Sigma Phase - An extremely brittle Fe-Cr phase that can form at elevatedtemperatures in austenitic and ferritic stainless steels.

Six Sigma - Statistical measurement of tightly controlled processes with the goal ofgenerating only 3.4 defects per million opportunities.

Slab - A common type of semi-finished stainless steel usually measuring 6-10 inchesthick by 30-85 inches wide and averaging 20 feet long. After casting, slabs are sent to astrip mill for rolling into sheet and plate products.

Slag - A layer formed on the surface of the molten metal which serves as a reservoir

for the various metallic oxides formed during melting and refining.

Slitt ing - Cutting a sheet of stainless steel into narrower strips.

Solution Heat Treatment - Heating a metal to a high temperature and maintaining itlong enough for one or more constituents to enter the solid solution. The solution isthen cooled rapidly to retain the constituents within.

Solution treating and aging - Strengthening mechanism used in titanium alpha-betaalloys as well as PH stainless alloys and many nickel-based super alloys. For titaniumalloys, the solution treating temperature that is normally 50-150 F below the beta-transus of the material and, after water quenching, the material is aged at 800-

1200F.

Solvent Cleaning - The removal of contaminants such as oil, grease, dirt, salts, etc.,by cleaning with a solvent, steam, vapor, alkali or emulsion.

Specialty alloys - Alloys composed of two or more chemical elements that typicallyperform under very rigorous service conditions or that have special electrical, thermal,magnetic, corrosion resistant, or mechanical properties. Metals with distinct chemicaland physical properties. These alloys are produced for specific applications and areconsidered to be on the low end of superalloys.

Specialty Steel - Category of steel that includes high strength, stainless and toolsteels.

Specialty Tube - A wide variety of high quality, specialized tubular products. It isusually found in the automotive and agricultural industries, construction equipment,hydraulic cylinders, etc.


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Stainless steel - Grades of steel with more than 10% chromium and often with otheralloying elements to resist corrosion, vary strength characteristics, and facilitatefabrication into parts.

Steckel Mill - A reversing stainless steel sheet reduction mill with heated coil boxes at

each end. Stainless steel sheet or plate is sent through the rolls of the reversing milland coiled at the end of the mill, reheated in the coil box, and sent back through theSteckel stands and recoiled. By reheating the stainless steel prior to each pass, the rollscan squeeze the stainless steel thinner per pass and impart a better surface finish.

Strain - The amount of elongation, force or compression that occurs in a metal at agiven level of stress. Generally in terms of inches elongation per inch of material.

Strength - The ability of stainless steel to oppose applied forces when consideringresistance to stretching, forming, compressing, etc.

Stress Corrosion Cracking (SCC) - Slowly developing cracks that form in stainless

steel due to mechanical stress and exposure to a corrosive environment.

Stress Relief- Low temperature annealing for removing internal stresses, such asthose resulting in a metal from work hardening or quenching.

Stress Relieving - Reducing residual stresses by heating.

Strip - Thin, flat steel that resembles hot-rolled sheet but is normally narrower and isproduced to more closely controlled thickness.

Structurals - An architectural stainless steel product group that includes I-beams, H-beams, wide-flange beams and sheet piling. These products are used in multi-story

buildings, bridges and vertical highway supports.

Superalloy (high-temperature alloy) - Alloy that can withstand very hot operatingenvironments up to 2000F (1093C) for some alloys and attendant corrosion andoxidation problems.

Tailored Blanks - A section of sheet stainless steel that is cut to the manufacturersrequirements. Excess stainless steel is trimmed away to save transportation costs andis ready for the stamper to shape with a die press.

Tandem Mill - A cold-rolling mill that gives greater strength, a more uniform and

smoother surface, and a reduced thickness to the stainless steel sheet. This mill rollsstainless steel through a series of rolls, to achieve a desired thickness and surfacequality.

Tempered (Temper) - A term applied to cold worked material such as strip, sheetand wire, expressing the range of mechanical properties as produced by the cold work(as is quarter hard, half hard, etc.).


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Tempering (drawing) - A process of reheating quench-hardened or normalized steelto a temperature below the transformation range and then cooling at any rate desired.The primary purpose of tempering is to impart a degree of plasticity or toughness to thesteel to alleviate the brittleness of its martensite.

Tensile Strength (ultimate strength) The breaking strength of a material whensubjected to a tensile (stretching) force. Usually measured by placing a standard testpiece in the jaws of a tensile machine, gradually separating the jaws, and measuringthe stretching force necessary to break the test piece. Tensile strength is commonlyexpressed as pounds (or tons) per square inch of original cross section.

Thin wall tubing - Tubes with wall thickness that can be as thin as .005 inches (.127mm) yet remain structurally sound in many environments. Such thin walls minimize theweight of the tube.

Titanium alpha alloys Titanium alloys that are either pure (Commercially Pure Ti)or richer in alpha stabilizing elements.(i.e. Al, Sn, Ga ). These alloys cant bestrengthened by heat treat but have good weldability.

Titanium alphabeta alloys - Titanium alloys that contain at least one alphastabilizer and one beta stabilizer. These alloys can be strengthened by solution treatingand aging. Titanium 6Al-4V is a very common alphabeta alloy.

Titanium-Based Superalloys - Lightweight, corrosive-resistant alloys suitable forhigh temperatures. These alloys have been used for airplane parts. Titanium alloys canblended with aluminium, iron, vanadium, silicon, cobalt, tantalum, zirconium, andmanganese.

Titanium beta alloys Titanium alloys that are richer in beta stabilizing elements(i.e. Mo, V). These titanium alloys have great forgeability and high hardenability but arehigher in density.

Titanium - Structural metal that offers excellent corrosion and erosion resistance,superior strength-to-weight ratios, and high heat transfer efficiency.

Tool steel - Alloys of iron used in making tools and dies that offer strength andfabrication qualities. Typically, tool steels contain carbon, manganese, chromium,tungsten and other alloying elements.

Tolerances - Measures the allowable difference in product specifications between what

a customer orders and what the manufacturing company delivers.

Ton - Unit of measure for stainless steel scrap and iron ore.Gross Ton: 2,240 pounds.Long (net) Ton: 2,240 pounds.Short (net) Ton: 2,000 pounds. Normal unit of statistical raw material input andstainless steel output in the United States.Metric ton: 1,000 kilograms. (2,204.6 pounds or 1.102 short tons).


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Toughness - Property of resisting fracture or distortion. Usually measured by impacttest, high impact values indicating high toughness.

Trepan - To remove a cylindrical core in a metal bar, creating a hollow bar.

Tungsten (W) - A gray metal with high tensile strength. It is ductile, malleable, and

resistant to atmospheric elements and all acids except strong alkalis.

Tungsten carbide - Advanced material that is very hard and wear resistant, making itsuitable for severe service applications such as cutting and grinding tools.

Ultimate strength The maximum load divided by the original cross-sectional area ofa sample, resulting in the maximum stress a material can sustain without fracture.

Ultrasonic inspection - A particular type of inspection in which internal and externaldefects are located by studying the travel pattern of sound waves sent through thematerial.

Vacuum Annealing - Annealing that is done in a vacuum to prevent the alloy fromreacting with oxygen while at high temperatures. This process is particularly importantfor titanium alloys, where alpha-case can form at high temperatures when in thepresence of oxygen found in air furnaces. This type of annealing can also be used toreduce hydrogen content in titanium.

Vacuum Arc Remelting (VAR) - Refining process in which a previously meltedelectrode is remelted under a vacuum to produce a finer, more uniform grain structurein metals.

Vacuum Induction Melting (VIM ) - Manufacturing process in which raw materials

are melted within a vacuum using the heat from an induced magnetic field. VIMensures tight control of a metals chemistry and more consistent structural properties.

Vacuum Oxygen Decarburization (VOD) - A refinement of stainless steel thatreduces carbon content. Molten, unrefined stainless steel is heated and stirred by anelectrical current while oxygen enters from the top. Many undesirable gases escapefrom the stainless steel and are evacuated by a vacuum pump. Alloys and otheradditives are then mixed in to refine the molten stainless steel further.

Vanadium (V) - A grey metal that is normally used as an alloying agent for iron andstainless steel. It is also used as a strengthener of titanium-based alloys.

VAR See Vacuum Arc Remelting

VIM - See Vacuum Induction Melting

Wire - Finished product that is shipped in coils, can vary in shape, but is typically underone inch (25.4 mm) in diameter.


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Work Hardening - Increase in resistance to deformation (i.e. in hardness) producedby cold working.

Workability - The characteristic or group of characteristics that determine the ease offorming a metal into desired shapes.

Yield Strength (YS) - The stress (load/area) at which the metal changes from elasticto plastic in behavior, i.e., takes a permanent set.

Zirconium (Zr) - A strong, ductile metal obtained by the chemical processing ofzircon-bearing sands. It has good corrosion resistance at high temperatures and is usedas a structural material in nuclear reactors and cladding material for uranium.

glossary of material terms

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