- Ben Nordman
Back to School: The ABCs of Steel
With most of the country getting back to school, many children are getting back to the basics to refresh their memory of what they learned last year after what turned out to be an interesting summer. While the kids are getting back to the basics, so are we with the ABCs of Steel.
As a producer of industrial lifting magnets, our magnets work with steel constantly, with many customers using theses terms on a daily basis. The same is true with the other Obsidian Manufacturing brands, Arter Precision Grinders and Magna-Lock USA, we follow where the steel is.
Acid Brittleness-- Commonly attributed to the absorption of hydrogen, this is the brittleness induced in steel when it is pickled in a deluted solution of acid for the purpose of removing scale, or upon electroplating.
Acid Lining-- The inner bottom and lining of a melting furnace composed of materials having an acid reaction if in contact with a molten slag (sand, siliceous rock, or silica bricks).
Acid Steel-- Steel melted in a furnace having an acid bottom and lining and under a slag with acid reaction. The term has no reference to the acidity of the steel.
Aging-- The spontaneous change in the properties of a metal usually associated with the recovery of metal from an unstable condition produced by quenching(quenchaging) or by cold working (strainaging). Age hardening and aging are terms commonly used synonymously. See also "Precipitation Hardening."
Aircraft Quality Steel-- Steel which has been tested during manufacture and approved as suitable for production of Aircraft parts. Special precautions are taken to assure the best possible quality in making steel to pass Aircraft quality inspection. The severity of steel inspection varies with the type of application and the amount of stress to be imposed upon the part. Final interpretations are dependent upon the application for which the steel is specified.
Air Hardening (Air Quenching)-- A hardening process wherein the steel is heated to the hardening temperature and cooled in air. Unless steel is high in carbon or alloy, or both, it will not show much increase in hardness when air hardened.
Alloy-- A material with metallic properties composed of two or more elements of which at least one is a metal.
Annealing-- Annealing generally refers to the heating and controlled cooling of solid material for the purpose of removing stresses, making it softer, refining its structure or changing its ductility, toughness or other properties. Specific heat treatments covered by the term annealing include black annealing, blue annealing, box annealing, bright annealing, full annealing, graphitizing, malleablizing and process annealing.
Arc Welding-- Welding by an electrical arc formed between an electrode (carbon or metal) and the metal being welded, between two separate electrodes as in atomic hydrogen welding, or between separate pieces being welded as in
As Rolled-- When bars are hot rolled and allowed to cool in the air, they are said to be in the "as rolled" or natural condition.
Austempering-- A patented heat-treating process that consists of quenching an iron-base alloy from a temperature above the transformation range in a medium having a high rate of heat abstraction, and then maintaining the metal, until transformation is complete, at a substantially uniform temperature which is below that of pearlite formation and above that of martensite formation.
Austenite-- A phase in steels which consists of the gamma form of iron with carbon in solid solution. Austenite is tough, non-magnetic and tends to work-harden rapidly when cold worked in those steels which are austenitic at ordinary temperatures.
Austenitic Steel-- Steel which has a stable austenitic structure at normal (room) temperatures.
Banded Structure-- A characteristic microstructure consisting of parallel bands of ferrite and pearlite which run in the direction of working.
Bark-- Decarburized skin found just beneath the scale.
Base Box-- A unit of measure used in the tin plate industry corresponding to an area equal to 112 sheets of tin plate, each 14 x 20 in., or 31, 360 sq. in., or 217. 78 sq. ft.
Basic Bottom or Lining-- The inner lining and bottom of a melting furnace composed of materials having a basic reaction; these may be crushed burnt dolomite, magnesite, magnesite bricks, or basic slag.
Basic Steel-- Steel melted in a furnace with a basic bottom and lining and under a slag having a basic reaction. Most steel made in America is basic.
Bauxite-- The principle ore of aluminum, present in nearly all earthly materials and unavoidably present in most slags. Also used in the manufacture of alumina refractories for withstanding extremely high temperatures.
Bend Test-- A test commonly made by bending a cold sample of specified size through a specified circular angle. Bend tests provide an indication of the ductility of the sample.
Billet-- A semi-finished rolled ingot of rectangular cross section or nearly so. In general the term "billet" is used when the cross section ranges from 4 up to 36 sq. in., the width always being less than twice the thickness. Small sizes are usually classed as bars or "small billets." The term "bloom" is properly used when the cross section is greater than about 36 sq. in., though this distinction is not universally observed.
Black Annealing-- A process of box annealing of sheets prior to tinning whereby a black oxide color is imparted to the surface of the product.
Blackplate-- Cold reduced sheet steel ranging in width from over 12 in. to less than 32 in. and in gauge from 29 and lighter, in coils or cut lengths, and within the uniform Classification of Flat Rolled Carbon Steel Products.
Blast Furnace-- A shaft furnace supplied with a i r blast, usually hot, for producing pig iron by smelting iron ore. The furnace is continuous in operation, the raw materials (iron ore, coke, and limestone) are charged at the top, and the molten pig iron and slag are collected at the bottom and are tapped out at intervals.
Blister-- A defect in metal produced by gas bubbles either on the surface or formed beneath the surface while the metal is hot or plastic. Very fine blisters are called pinhead or pepper blisters.
Bloom-- See "Billet"
Blooming Mill-- Mill used to reduce ingots to blooms, slabs, etc.
Blowhole-- A hole produced during the solidification of metal by evolved gas which, in failing to escape, is held in the metal.
Blue Annealing-- A process of annealing sheets after rolling. The sheets, if fairly heavy, are allowed to cool slowly after the hot rolling; i f of lighter gauge, as is usually the case, they are passed singly through an open furnace for heating to the proper annealing temperature. As the name indicates, the sheets have a bluish-black appearance.
Blued Plate-- Blackplate with the surface oxidized at a suitable temperature
by steam or air to produce a blue color.
Blueing-- A method of coating sheets with a thin, even film of bluish black oxide. The blued surface is obtained by exposure to an atmosphere of dry steam or air at a temperature of about 1000°F. Generally this is done during box annealing.
Box Annealing-- Softening steel by heating, usually at a subcritical temperature, in a suitable closed metal box or pot to protect it from oxidation, employing a slow heating and cooling cycle; also called close annealing or pot annealing.
Bright Annealing-- An annealing process usually carried out in a controlled furnace atmosphere so that surface oxidation is reduced to a minimum and the surface remains relatively bright.
Brinell Hardness Test-- This test consists of forcing a ball of standard diameter into the specimen being tested under standard pressure, and judging the hardness of the material by the amount of metal displaced.
British Thermal Unit-- A unit of heat representing the amount of heat necessary to raise the temperature of one pound of water one degree Fahrenheit. Abbreviated B. T. U. or BTU.
Burning-- Heating steel to a temperature sufficiently close to the melting point to cause permanent injury. Such injury may be caused by the melting of the more fusible constituents, by the penetration of gases such as oxygen into the metal with consequent reactions, or perhaps by the segregation of elements already present in the metal.
Calorizing-- A process of converting the surface of steel articles into a corrosion-resistant alloy layer of aluminum and iron by surface absorption of aluminum from a mixture of aluminum and aluminum oxide powder at elevated temperatures.
Camber-- In sheet or strip: the greatest deviation of a side from a straight line. In structurals: the curvature from the plane of a flange in the length of the section, either leg of an angle being taken as the flange. (Also see Sweep).
Carbides-- As found in steel, carbides are compounds of carbon and one or more of the metallic elements, such as iron, chromium, tungsten, etc.
Carbon Free-- Metals and alloys which are practically free from carbon.
Carbo-Nitriding-- A process of case hardening an iron-base alloy by the simultaneous absorption of carbon and nitrogen through heating in a gaseous atmosphere of suitable composition, followed by cooling at a rate that will produce desired properties.
Carbon Range-- In steel specifications, the carbon range is the difference between the minimum and maximum amount of carbon acceptable.
Carbon Steel-- Steel whose major properties depend on its carbon content and in which other alloying elements are negligible.
Carburizing-- Adding carbon to iron-base alloys by absorption through heating the metal at a temperature below its melting point in contact with carbonaceous materials. Such treatment followed by appropriate quenching hardens the surface of the metal. The oldest method of case hardening.
Carburizing Compound-- Mixtures containing carbonaceous solids which will give up carbon to steel in the presence of heat. Gas rich in carbon is sometimes used in the carburizing process.
Case-- The surface layer of an iron-base alloy which has been made substantially harder than the interior by the process of case hardening.
Case Hardening-- Carburizing, nitriding, or cyaniding and subsequent hardening, by heat treatment, all or part of the surface portions of a piece of iron base alloy.
Cast Steel-- Any object made by pouring molten steel into molds.
Casting Strains-- Strains produced by internal stresses resulting from the cooling of a casting.
Charpy Test-- A test made to determine the notched toughness, or impact strength, of a material. The test gives the energy required to break a standard notched specimen supported at the two ends.
Check Analysis-- Analysis of metal after it has been rolled or forged into semi-finished or finished forms.
Chemical Analysis-- Qualitative analysis consists of separating a substance into its component elements and identifying them. In quantitative analysis the proportion of all component elements are determined.
Chemical Requirements-- When specifying to chemical composition, base requirements should be based on the standard limits and ranges together with the standard permissible variation for check analysis and standard methods of sampling published by AISI for each product.
Chipping-- One method of removing surface defects such as small fissures or seams from partially worked metal. If not eliminated, the defects might carry through to the finished material. If the defects are removed by means of a gas torch the term "deseaming" or "scarfing" is used.
Chromium-- A hard, corrosion resistant metal widely used as an alloying element in steel and for plating steel products.
Cleavage Plane-- Crystals possess the property of breaking more readily in one or more directions than in others. The planes of easy rupture are called cleavage planes.
Close Tolerance-- Hot-rolled material is classed as close tolerance when furnished to size tolerances more restrictive than standard-- in no case closer than 1/ 2 the standard variation.
Coining-- A method of cold forming or sizing metal by compression, often used for imparting smooth finish and close tolerances.
Cold Finishing-- Changing the shape of or reducing the cross section of steel while cold- usually accomplished by rolling, drawing through a die or turning.
Cold Heading-- Forcing cold metal to flow into dies to form thicker sections and intricate shapes.
Cold Rolling-- See "Cold Finishing."
Cold Shut-- An area in metal where two portions of the metal in either a molten or plastic condition have come together but have failed to unite into an integral mass.
Cold Working-- Permanent deformation of a metal below its recrystallization temperature, which hardens the metal.
Combined Carbon-- All of the carbon in iron or steel which is combined with iron or other elements to form carbide.
Compressive Strength-- Yield: Maximum stress that a compressed metal can withstand without a predefined amount of deformation. Ultimate: Maximum stress a brittle metal can withstand without fracturing when subjected to compression.
Consumable Electrode Melting-- An ingot of steel is remelted in a vacuum by making the ingot serve as a consumable electrode. Purpose: to refine the steel. The melted ingot collects in a watercooled copper mold.
Continuous Mill-- A mill in which several stands of rolls are arranged in tandem, usually so close together that the steel passes through several stands simultaneously—for example: bar mills, strip mills, and some newer plate mills.
Controlled Cooling-- Cooling from elevated temperature in a predetermined manner to avoid hardening, cracking or internal damage, or to produce a desired microstructure. Such cooling usually follows the final forming operation.
Core-- The center portion of a piece of steel which may be of different chemical composition than the outside, as in the case of carburized parts, or which may have different physical properties than the outside due to the failure of penetration of heat treatment effect.
Creep-- Plastic deformation or flow of metals held for long periods of time at stresses lower than normal yield strength. Especially important if temperature of stressing is near recrystallization temperature of the metal.-
Creep Strength-- The maximum stress which can be applied to steel at a specified temperature without causing more than a specified percentage increase in length in a specified time.
Creep Test-- A number of samples, each loaded to a different stress, are placed in heating coils and held at a constant predetermined temperature. Tests are conducted for periods ranging from 1000-2000 hours during which time the samples stretch. The elongation is measured and recorded at regular intervals. The results show the amount of elongation which can be expected when the steel is subjected to a given stress and temperature within a given time.
Critical Points Of Temperatures-- The various temperatures at which transformations occur in steel as it passes through its critical range- on either a rising or falling temperature. (See Transformation Range.)
Critical Range-- A temperature range in passing through which steel undergoes transformation. The preferred term is transformation range (q. v.).
Crop-- The imperfect ends of a rolled or forged product which are removed and discarded.
Cryogenics-- Working with materials in environments near absolute zero (-459. 69° F).
Cup Fracture-- A type of fracture-- which looks like a cup having the exterior portion extended with the interior slightly depressed-- produced in a tensile test specimen. Usually an indication of ductility.
Cyaniding-- Surface hardening of an iron-base alloy article or portion of it by heating at suitable temperatures in contact with molten cyanide salt and then quenching.
Decalescence-- The absorption of heat. due to internal changes. which occurs when steel is heated through the critical temperature range.
Decarburization-- The loss of carbon from the surface of solid steel during heating, forging. hot rolling, etc.
Deep Drawing-- The process of working metal blanks in dies on a press into
shapes which are usually more or less cup-like in character.
Deep Etching-- Etching, for examination a low magnification, by a reagent that attacks the metal to a much greater extent than is normal for microscopic examination—may bring out such features as abnormal grain size segregation, cracks or grain, flow.
Deoxidize-- The removal of oxygen. present as iron oxide, from molten steel by adding a deoxidizing agent such as manganese, silicon or aluminum.
Deoxidized Sheets-- Hot rolled sheets that have been bright annealed.
Depth Of Penetration-- The depth to which appreciable hardening occurs when steel is quenched from its hardening temperature.
Diamond Pyramid Hardness Test-- An indentation hardness test employing a 136° diamond pyramid indenter and variable loads enabling the use of one hardness scale for all ranges of hardness from soft lead to tungsten carbide.
Differential Heating-- Heating so that various portions of an article reach different temperatures to produce different properties upon cooling.
Distortion-- A change in shape (usually refers to changes of shape caused by internal stress).
Double Vacuum Melting-- Ingots made by the vacuum induction melting method are re-melted and further refined by the consumable electrode method.
Drawing-- Drawing may refer to the pulling of steel through a die. as in drawing wire, or deforming steel in dies on a press (deep drawing).
Drawing Back-- Reheating after hardening to a temperature below the critical for the purpose of improving the ductility and or lowering the hardness of the steel.
Drawing Quality-- Flat rolled steel which can withstand extreme pressing, drawing or forming, etc. without creating defects. Produced from deep-drawing rimmed steels or extra deep-drawing aluminum-killed steels which are special rolled and processed.
Ductility-- The ability to permit change of shape without fracture. In steel, ductility is usually measured by elongation and reduction of area as determined in a tensile test.
Eccentricity Of Tubing-- Variation on wall thickness. when the wall is lighter on one side and heavier at a point 180° away, resulting in the ID of the tube being not concentric with the OD.
Eddy-Current Test-- Nondestructive testing method in which eddy-current flow is induced in the test object. Changes in the flow caused by variations in the object are reflected into a nearby coil or coils for subsequent analysis by suitable instrumentation and techniques.
Edge Condition-- Mill Edge: Normal edge produced in rolling. conforms to no definite contour. Sheared Edge: One cut after rolling. Slit Edge: Produced when strip or coil is slit into multiple widths.
Elastic Limit-- The maximum load per unit of area (usually stated as pounds per square inch) that may be applied without producing permanent deformation. It is common practice to apply the load at a constant rate of increase and also measure the increase of length of the specimen at uniform load increments. The point at which the increase in length of the specimen ceases to bear a constant ratio to the increase in load. is called the proportional limit. The elastic limit will usually be equal to or slightly higher than the proportional limit.
Elongation-- The increase in length of a test specimen after rupture in a tensile test, expressed as a percentage of the original length.
Endurance Limit-- Maximum dynamic stress to which material may be submitted for an infinite number of times without causing fatigue failure.
Etching-- Revealing structural details by preferential attack of reagents on a metal surface.
Etch Tests-- Etching to detect inclusions in steel. A common test is dipping a sample into acid which reacts with the inclusions to disclose their presence.
Eutectoid Steel-- Carbon steel with a 100 per cent pearlitic structure, which is the structure developed under normal conditions of hot working and cooling when the proportion of carbon is about . 80 per cent. Hyper-eutectoid steel has a greater percentage of carbon, and hypo-eutectoid steel has less carbon.
Extensometer-- An instrument for measuring changes caused by stress in a linear dimension of a body.
Extruding-- Shaping metal in continuous form by forcing it through a die.
Fatigue-- The tendency for a metal to break under conditions of repeated cyclic stressing below the ultimate tensile strength.
Fatigue Limit-- See “Endurance Limit.”
Fatigue Test-- Highly polished samples are subjected to stress while bending, which results in a reversal of stress of every complete revolution. The stress is reduced on each succeeding sample until the maximum stress a sample will sustain for ten million reversals has been reached. Since experience justifies the assumption that if steel can withstand ten million reversals, it can withstand such stress indefinitely. This stress is reported as the fatigue limit.
Ferro Alloys-- Iron alloyed with some element such as manganese, chrome, or silicon, etc., used in adding the element to molten steel.
Fiber-- A characteristic of wrought metal manifested by a fibrous or woody appearance of fractures and indicating directional properties. Fiber is due chiefly to the extension in the direction of working of the constituents of the metal, both metallic and non-metallic.
Fiber Stress-- Unit stress at a certain point when overall section stress is not uniform.
Fin-- Protuberances resulting from the improper squeezing of steel during
rolling. Also see "Flash."
Finished Steel-- Steel which is ready for the market without any further work or treatment such as wire, bars, sheets, rails, plates. etc. Blooms, billets, slabs, and wire rods are termed semi-finished.
Finishing Temperature-- Temperature at which hot mechanical working of metal is completed.
Firebox Quality-- Quality of plates for use in pressure vessels which will be exposed to fire or heat and the resulting thermal and mechanical stresses.
Flakes-- An internal steel fracture with a bright, scaly appearance.
Flame Annealing-- The direct application of a high-temperature flame to a steel surface for the purposes of removing stresses and softening metal. Commonly used to remove stresses from welds.
Flame Cutting-- Commonly denotes the producing of shapes from flat steel with single or multiple torch setups. Torches may be guided by hand, mechanically or by an electric eye.
Flame Hardening-- In this method of hardening, the surface layer of a medium or high carbon steel is heated by a high-temperature torch and then quenched.
Flange Quality-- Quality of plates for use in pressure vessels which are not exposed to fire or radiant heat. Special manufacturing, testing and marking are required.
Flash-- A thin fin of metal formed at the sides of a die forging or sometimes a rolled bar where a small portion of the metal is forced out between the edges of the forging dies or the rolls.
Flash Point-- Ignition point- usually applied to oils.
Forging-- A piece of metal which has been shaped or formed, while hot, by forging with a hammer (hand or power), in a press, or by a drop hammer.
Forging Quality-- Semi-finished steel produced for applications involving forging require manufacturing control for chemical composition, deoxidization mold practice, pouring, rolling, discard, cooling surface preparation, testing and inspection. Purchaser's method of fabrication and end use is a vital consideration in producing steel to this broad definition.
Forging Stresses-- Stresses resulting from forging or from cooling from the forging temperature.
Fracture-- The surface of a break in metal.
Fracture Test-- Breaking metal to determine structure or physical condition by examining the fracture.
Free Machining-- A term used to describe a metal which may be machined with less power at relatively high speed without the development of excessive heat and from which the chips will break off easily leaving a smooth surface. Free machining steel has internal friction reduced by alteration of the chemical composition through the modification of the carbon, manganese, Sulphur or selenium content or by addition of lead.
Full Annealing-- Heating to above the critical temperature range followed
by slow cooling through the range, producing maximum softness.
Full Hardness-- Usually the hardness of heat treated steel after quenching
and before tempering.
Galvanizing-- Applying a coating of zinc to finished cold-reduced sheet or to fabricated parts made from strip products. Application may be by hot dip (either hand or continuous) or electrolysis.
Galvannealing-- Applying an extra tight coat of zinc to a soft steel sheet, then passing through an oven at about 1200° F. Gives a dull gray unspangled coat well suited for painting.
Grain Growth-- The increase in the size of grains making up the microstructure of steel such as may occur during heat treatment.
Grain Refinement-- Reducing the crystalline or grain structure by heat treating, or by a combination of heat treating and mechanical working.
Grain Structure-- The type of crystalline structure as observed by eye or under the microscope.
Graphitizing-- Annealing gray cast iron so that most of the carbon is transformed to the graphitic condition. Controlled by increasing silicon and by thermal treatment.
Hardenability-- (Of Steel) The ability of a steel to harden when cooled from
its hardening temperature, as measured by its surface hardness and by the
depth of hardening below the surface.
Hardening-- (As applied to heat treatment of steel.) Heating and quenching to
produce increased hardness.
Heat Of Steel-- The steel produced from one charge in the furnace, and consequently
practically identical in its characteristics.
Heat Resisting Steels-- Those steels which are used for service at
relatively high temperatures because they retain much of their
strength and resist oxidation under such condition.
Heat Tinting-- Heating a polished specimen in a i r for the purpose of
obtaining an oxidized surface.
Heat Treatment-- An operation or combination of operations involving
the heating and cooling of steels in the solid state for the purpose of
obtaining certain desirable mechanical, microstructural or corrosionresisting
HIGH DRAW-- A drawing temperature not very much below the Ac1 point of
the steel- used to develop high ductility when tempering steel after
HIGH STRENGTH STEEL -- A specific class of low alloy steels in which
increased mechanical properties and, usually, good resistance to
atmospheric corrosion are obtained with moderate amounts of one
or more alloying elements other than carbon. Preferably called
high-strength, low-alloy steels.
HOT SHORTNESS-- Brittleness in metal, at an elevated temperature.
HOT WORKING-- The mechanical working of metal above the recrystallization
Impact Test-- Determines the energy absorbed in fracturing a test bar at high velocity. Test may be in tension or bending, or may be a notch test (Izod V -Notch or Charpy Key-Hole) in which the notch creates multiazial stresses.
Impact Values-- Resistance to shock and ability to distribute localized stress as measured by impact test-- usually expressed in foot-pounds.
Inclusions-- Particles of non-metallic material usually oxides, sulphides, silicates and such which are entrapped mechanically or are formed during solidification or by subsequent reaction within the solid metal.
Induction Hardening-- A hardening process in which the part is heated above the transformation range by electrical induction.
Ingot-- A casting intended for subsequent rolling or forging. Usually cast in metallic molds.
Ingot Iron-- Open hearth iron low in carbon, manganese and other impurities. Commonly call "pure iron". Sometimes used for making enameling sheets, and, with silicon added, for high grade electrical sheets.
Intergranular Corrosion-- Electrochemical corrosion along the grain boundaries of an alloy, usually caused because the boundary regions contain material anodic to the center of the grain.
Iron-- A metallic element. However, in the steel industry, iron represents the product of a blast furnace containing 92% to 94% iron. Blast furnace iron is also called pig iron or hot metal.
Izod Test-- A test made to determine the notched toughness of a material. The test gives the energy required to break a standard notched specimen supported as a cantilever beam.
Jominy End-Quench Test--This is a hardenability test in which a steel sample is heated to its proper quenching temperature and subjected to a spray of water at one end, a quenching method which provides a very rapid rate of cooling at the end sprayed, with progressively slower cooling all the way up to the other end. See full discussion in mech. properties section.
Killed Steel-- Steel to which sufficient deoxidizing agents have been added to prevent gas evolution during solidification.
Kip-- A unit of load equaling 1000 pounds or 453. 59 kilograms.
Ladle Analysis-- Determined by chemical analysis for specific elements of a test ingot sample obtained from the first part of middle part of a heat or blow during the pouring of the steel from the ladle. This is the analysis reported to the purchaser.
Laminations-- Defects caused by blister, seams or foreign inclusions aligned parallel to the working surface of a metal.
Lap-- A surface defect appearing as a seam caused from folding over hot metal, fins, or sharp corners and then rolling or forging, without welding them into the surface.
Long Ternes-- Flat rolled steel in sheet sizes coated with a mixture of lead and tin. Coating usually contains 80% to 85% lead and 15% to 20% tin.
Machinability-- The ease of metal removal during machining, the tool life obtained, the surface finish obtained or any combination of these three.
Machine Straightening-- Straightening metal bars by rolling in a straightening machine.
Macroetch Test-- Deep etching steel in a hot acid solution to evaluate soundness and homogeneity without magnification.
Magnaflux Test-- A method of detecting cracks, laps, and other defects by magnetizing the steel and applying fine magnetic particles (dry or suspended in solution). Presence of a surface or subsurface defect is indicated by a particle pattern.
Magnetic-Analysis Inspection-- A nondestructive method of inspection for determining the existence and extent of possible defects in ferromagnetic materials. Finely divided magnetic particles, applied to the magnetized part, are attracted to and outline the pattern of any magnetic leakage fields created by discontinuities.
Malleability-- The property of a metal to deform when subjected to rolling or hammering. The more malleable a metal is, the easier it can be deformed.
Malleabilizing-- An annealing operation performed on white cast iron for the purpose of partially or wholly transforming the combined carbon to temper carbon, and in some cases to remove completely the carbon from the iron by decarburization.
Maraging Steels-- A group of high nickel martensitic steels developed by the International Nickel Co. Their high strength and ductility evolve primarily from the aging of a martensitic matrix.
Martensite-- With most steels, cooling as rapidly as possible from their quenching temperature develops a distinctive structure called martensite. In this form, the steel is at its maximum hardness.
Matrix-- The ground mass or principal substance in which a constituent is embedded.
McQuaid-Ehn Test-- A test for revealing grain size of steel by heating above critical range in a carbonaceous medium. This causes grains to be outlined sharply when polished, etched and viewed under a microscope. Grain sizes range from No. 8 (finest) to No. 1 (coarsest).
Mean Dimension-- The average of minimum and maximum mill tolerances; generally used in connection with tubing on OD, ID or wall dimension.
Mechanical Properties-- Properties of a material that reveal the reaction when force is applied, or that involve the relationship between stress and strain, such as modulus of elasticity, tensile strength and fatigue limit. The term "mechanical properties" is preferred to "physical properties."
Merchant Bar Quality Steel-- A standard steel, free from visible pipe, widely used for general production and repair work, bracing, machine parts, welding jobs, etc. It is not particularly recommended for forging, heat treating or complicated machine operations.
Microscopic-- Extremely small-- not large enough to be seen with the naked eye.
Microstructure-- The structure of metals as revealed by examination of polished and etched samples with the microscope.
Mill Edge-- Replaces "band edge"; see "Edge Condition."
Modulus Of Elasticity-- Within the proportional limit, if the stress (in lbs. per sq. inch) is divided by the strain (stretch in inches per inch) a value will be obtained which is called the modulus of elasticity of the material. This value for steel is about 30,000,000.
Network Structure-- A structure in which the crystals of one constituent are partially or entirely surrounded by envelopes of another constituent, an arrangement that gives a network appearance to a polished and etched specimen
Nickel Steel-- Alloy steel containing nickel at its principal alloying element.
Nitriding-- Adding nitrogen to the solid iron-base alloys by heating at a temperature below the critical in contact with ammonia or some other nitrogeneous material.
Nominal Dimension-- OD, ID, or wall thickness of tubing specified by buyer, regardless of how the tolerances are expressed.
Normalizing-- Heating to about 100 ° F. above the critical temperature and cooling to room temperature in still air. Provision is often made in normalizing for controlled cooling at a slower rate, but when the cooling is prolonged the term used is annealing.
OIL QUENCH-- A quench from the hardening temperature, in which oil is the cooling medium.
OLSEN TEST-- This is a· cupping test made on an Olsen machine as an aid in determining ductility and deep drawing properties. The test simulates a deep drawing operation. It is continued until the cup formed from the steel sample fractures. Ductility and drawing properties are judged by the depth of the cup, position of the break, condition of the surface after the break, etc.
OUT-OF-ROUND-- The difference between maximum and minimum diameters of a bar measured at the same cross section ..
OUT-OF-SQUARE-- The difference between two dimensions of a square bar, each dimension being the distance between opposite sides and both measured at the same cross section.
OVERHEATING-- Heating to such a temperature that, while the properties of the metal are impaired, it has not been burned and can therefore be rendered by heat treatment.
Passivation--Generally refers to a process for the surface treatment of stainless steels. Material is subjected to the action of an oxidizing solution, usually nitric acid, which augments and strengthens the normal protective oxide film enabling the material to resist corrosive attack. The passivating process also removes foreign substances from the surface which might cause local corrosion.
Patenting--Heating iron-base alloys above the critical temperature range followed by cooling below that range in air, or in molten lead or a molten salt maintained at a temperature usually between 800-1050° F, depending on the carbon content of the steel and the properties required of the finished product.
Pearlite-- A relatively hard constituent of steel made up of alternate layers of ferrite (iron). and cementite (iron carbide; that is, a compound of iron and carbon). See "Eutectoid Steel. "
Permanent Set--Permanent change in shape due to application of stress.
Phosphorus Banding-- A visible band occurring in metals caused by localized phosphide segregations.
Photomicrograph-- A photographic reproduction of an object magnified more than 10 times. Used to study the grain structure of steel.
Physical Properties-- Properties exclusive of those listed under mechanical properties such as density, electrical conductivity and coefficient of thermal expansion. Term is often used to describe mechanical properties but such usage is not recommended.
Pickling-- Immersion of steel in a dilute solution of acid for the purpose of removing the scale.
Piercing--Process of spinning and rolling a billet over a mandrel in such a way that a hole is opened in the center.
Pipe-- A cavity formed in metal (especially ingots) during the solidification of the last portion of liquid metal. Contraction of the metal causes this cavity or pipe.
Pit-- A depression in the surface of metal occurring during its manufacture.
Precipitation Hardening--The process of hardening an alloy by heating it for the purpose of allowing a structural constituent to precipitate from a solid solution.
Preheating-- As a general term, preheating means a heating applied preliminary to some further thermal or mechanical treatment. It also has a specific meaning in describing the process by which tool steel is heated slowly and uniformly to a temperature below the hardening temperature, following which the steel is transferred to a furnace in which the temperature is substantially above the preheating temperature.
Process Annealing-- Heating to a temperature below or close to the lower limit of the critical temperature range and then cooling as desired.
Proportional Limit- -The greatest load per square inch of original cross-sectional area for which the elongation is proportional to the load.
Pyrometer-- An instrument used for measuring temperatures.
Quench Hardening-- Hardening a ferrous alloy by heating within or above the transformation range and cooling at a controlled rate. This usually involves formation of martensite.
Quenching-- Cooling rapidly by immersion in oil, water, etc.
Quenching Medium-- The medium used for cooling steel during heat treatment- usually oil, water, air, or salts.
Quenching Temperature-- The temperature from which steel is quenched during a heat treating process.
Radiography-- A nondestructive method of internal examination in which metal or other objects are exposed to a beam of x-ray or gamma radiation. Differences in thickness, density or absorption, caused by internal discontinuities, are apparent in the shadow image either on a fluorescent screen or on photographic film placed behind the object.
Random Lengths-- A term indicating no specified minimum or maximum length with lengths falling within the range indicated.
Recalescence-- The liberation of heat due to internal changes, which occurs when steel is cooled through the critical temperature range.
Red Shortness-- See "Hot Shortness."
Reduction Of Area-- The difference between the original cross-sectional area of a tensile specimen and that of the smallest area at the point of rupture. It is usually stated as a percentage of the original area; also called "contraction of area. "
Refinement Of Structure-- See "Grain Refinement."
Refining Temperature-- A temperature employed in heat treatment to refine structure, in particular, to refine the grain size. Usually just above AC3 in steel.
Regenerative Quenching-- Quenching carburized parts from two different temperatures to refine case and core. (Often called double quenching.)
Rimmed Steel-- A steel that is poured containing enough oxygen to evolve appreciable gas during solidification. The gas evolution results in a finished product having a very pure surface with the impurities concentrated in the interior. The pure zone which is readily shown by etching is referred to as the "rim".
Rockwell Hardness Test-- Forcing a cone-shaped diamond or hardened steel ball into the specimen being tested under standard pressure. The depth of penetration is an indication of the Rockwell Hardness.
Rolled Edge-- The edge on a universal plate when rolled by both vertical and horizontal rolls. Edge shearing is not necessary.
Roller Leveler-- A rolling device used for eliminating buckles and waves in steel sheets and strip and for producing sheets of commercial flatness. The roller leveler has sets of rolls that are staggered to flex the sheet as it passes between them. Besides its use in leveling, it has extensive application for minimizing or temporarily eliminating the tendency to develop stretcher strains.
Roll Threading-- Threading a bolt or screw by rolling it between two grooved die plates, one of which is in motion, or between rotating grooved circular rolls.
Scab-- A defect on the ingot caused by metal which splashes during teeming; on rolled or forged products it appears as a silver-like defect partially welded or mechanically bound to the parent metal surface.
Scale-- An iron oxide formed on the surface of hot steel, sometimes in the form of large sheets which fall off when the steel is rolled.
Scleroscope Or Shore Hardness Test--This test consists of dropping a small diamond tipped hammer from a standard height onto the surface of the specimen being tested. The height to which the hammer rebounds is a measure of the surface hardness of the specimen.
Screw Stock-- Metal in the form of a wire or rod, ordinarily a free-machining type, used for making screw machine products.
Seam-- An elongated discontinuity in metal caused by a blowhole or other defect which has been closed by rolling or forging mechanically but not welded.
Secondary Hardening-- An increase in hardness following the normal softening during the tempering of certain alloy steels.
Segregation-- Concentration of the components of steel with the lowest freezing point in parts of the ingot which solidify last.
Semi-Killed Steel-- Characterized by variable degrees of uniformity and compositions and have properties intermediate between those of killed and rimmed steels.
Shear Strength-- The stress required to produce fracture in the plane of a cross section, the conditions of loading being such that the directions of force and of resistance are parallel and opposite although their paths are offset a specified minimum amount.
Sherardizing-- A cementation process used to give small steel articles, such as bolts, a corrosion resistant surface of zinc-rick alloy. The articles are packed with zinc dust in drums which are heated for several hours while slowly rotating.
Silky Fracture-- A steel fracture having a very smooth, fine grain, or silky appearance.
Skelp-- Steel or iron plate from which pipe or tubing is made.
Sketch Plates-- Plates cut to shapes other than rectangular.
Slab-- A thick rectangular pie