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- Published: Thursday, 20 June 2013 17:13
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AGE HARDENING (AGING)- Spontaneous, gradual change in mechanical properties causing increased hardness, yield strength and tensile strength accompanied by a loss of ductility. Nonkilled cold rolled steels are especially prone to this condition.
AISI STEELS- Steels specified by the AMERICAN IRON AND STEEL INSTITUTE.
ALLOY STEEL- Steel containing substantial amounts of elements other than carbon and the commonly accepted limited amounts of manganese, sulfur, silicon and phosphorus. Addition of such alloying elements is usually for the purpose of increased hardness, strength or chemical resistance. The metals most commonly used for forming alloy steels are: nickel, chromium, silicon, manganese, tungsten, molybdenum and vanadium.
ALUMINUM- (Chemical Symbol AI) - Silvery white metal used in steelmaking as a 1.) deoxidizer; 2.) grain refiner; 3.) alloying agent in nitriding steels; and 4.) a coating for aluminized steels.
ALUMINIZED STEEL- Steel coated with aluminum by a hot dip process to impart corrosion resistance.
ANNEALING- A generic term denoting a treatment, consisting of heating to and holding at a suitable temperature followed by cooling at a suitable rate, used primarily to soften metallic materials, but also to simultaneously produce desired changes in other properties or in microstructure. The purpose of such changes may be, but is not confined to, one or more of: improvement of machinability; facilitation of coldwork; improvement of mechanical or electrical properties or increase in stability of dimensions.
ASTM- Abbreviation for AMERICAN SOCIETY FOR TESTING MATERIAL. An organization for issuing standard specifications on materials.
AUSTEMPERING- A heat treating process that consists of quenching steel from a temperature above the transformation range into a medium (usually molten salt) having a rate of heat extraction sufficiently high to prevent the formation of pearlite by maintaining the temperature between the pearlite temperature range and the martensite start temperature until transformation is complete.
AUSTENITE- A phase in plain carbon and low alloy steels that is stable only above approximately 1330°F. Certain high alloy and stainless steels contain sufficient amounts of austenite stabilizer (nickel, manganese) to be austenitic at room temperature.
AUSTENITIZING- Forming austenite by heating a ferrous alloy into the transformation range (partial austenitizing) or above the transformtion range (complete austenitizing). When used without qualification, the term implies complete austenitizing.
BAINITE- A needle-like, acicular microstructure appearing in spring steel strip characterized by high hardness with ductility and toughness greater than tempered martensite. Bainite is produced by cooling austenite at a rate sufficiently fast to avoid formation of pearlite and holding at a temperature below that at which pearlite forms but above the martensite start temperature.
BANDED STRUCTURE- A microstructure consisting of parallel bands of iron carbide and ferrite.
BASE BOX- An arcane method of designating thickness that is peculiar to tin mill products (see TIN PLATE BASE BOX).
BASIC OXYGEN PROCESS- A pneumatic steelmaking process wherein high purity oxygen is blown onto the surface of a bath of molten iron oxidizing impurities and promoting slag-metal refining reactions.
BATCH ANNEAL- Any process involving annealing of steel in coils. Because of the large masses of steel involved, heat up and cool down rates are relatively low.
BEND TEST- A test used to index the ductility or formability of flat rolled steel which consists of bending the material around a specified radius that is frequently expressed in multiples of the material thickness (1 x T = a radius that is one times the thickness of the material). The direction of the bend axis is normally specified also: along the rolling direction (unfavorable) or transverse to the rolling direction favorable).
BLACK PLATE- A light weight or a thin uncoated steel sheet or strip so called because of its dark oxide coloring prior to pickling. It is manufactured by two different processes. (1) From sheet bar on single stand sheet mills or sheet mills in tandem. This method is now almost obsolete. (2) On modern, high speed continuous tandem cold reduction mills from coiled hot rolled pickled wide strip into ribbon wound coils to finished gage. Sizes range from 12" to 32" in width, and in thicknesses from 551bs. to 2751bs. base box weight. It is used either as is for stampings, or may be enameled or painted or tin or terne coated.
BLANK- A flat piece of steel produced in blanking dies or by shearing for an identified part. Blanks are usually formed further in subsequent press operations.
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 iron ore, coke and limestone as raw materials which are charged at the top while the molten iron and slag are collected at the bottom and are tapped out at intervals.
BLISTER- A small raised area on the surface resulting from the expansion of gas concentrated at a subsurface inclusion or porosity. May occur as isolated spots, but often found in longitudinal streaks.
BLUING- (1) Sheets - A method of coating sheets with a thin, even film of bluish-black oxide, obtained by exposure to an atmosphere of dry steam or air; generally this is done during box annealing. (2) Tempered spring steel strip - an oxide film blue in color produced by low temperature heating.
BONDERIZING- The coating of steel with a film composed largely of zinc phosphate in order to develop a better bonding surface for paint or lacquer.
BORON- (Chemical Symbol B) - an alloy addition that is used to improve hardenability or reduce hardness. In medium and high carbon steels up to approximately .50 carbon, boron, added with small amounts of titanium for protection from nitrogen, enhances heat treat response. In low carbon, aluminum killed steels, unprotected boron additions combine with the nitrogen present which reduces the material's as-hot rolled hardness.
BOX ANNEALING- A process of heating coils of steel in a closed container filled with a non-oxidizing atmosphere. The charge is usually heated slowly to a temperature below the transformation range, held for sufficient time to equalize temperature throughout the coil, and then slow cooled. When used commercially, a BOX ANNEAL implies a shorter, less costly anneal than a SPHEROIDIZED ANNEAL.
BRAKE- A piece of equipment used for bending sheet; also called a bar folder. If operated manually, it is called a hand brake; if power driven, it is called a press brake.
BRALE- A diamond penetrator, conical in shape, used with a Rockwell hardness tester for hard metals. Uses include Rockwell A and C scales.
BRAZING- Joining metals by fusion of nonferrous alloys that have melting points above 800°F. but lower than those of the metals being joined. This may be accomplished by means of a torch (torch brazing), in a furnace (furnace brazing) or by dipping in a molten flux bath (dip or flux brazing). The filler metal is ordinarily in rod form in torch brazing; whereas in furnace and dip brazing the work material is first assembled and the filler metal may then be applied as wire, washers, clips, bands, or may be integrally bonded, as in brazing sheet.
BREAKS- Creases or ridges usually in 'untempered' or in aged material where the yield point has been exceeded. Depending on the origin of the break, it might be termed a crossbreak, a coil break, an edge break, a sticker break, etc.
BRIGHT ANNEALING- A process of annealing usually carried out in a controlled furnace atmosphere so that surface oxidation is reduced to a minimum and the surface remains relatively oxide free.
BRIGHT COMMERCIAL FINISH- Refer to FINISHES.
BRINELL HARDNESS (TEST)- A common standard method of measuring the hardness of relatively thick metals. The smooth surface of the metal is subjected to indentation by a hardened steel ball under pressure or load. The diameter of resultant indentation in the metal surface is measured by a special microscope and the Brinell hardness value read from a chart or calculated by formula.
BRITTLENESS- A tendency to fracture without appreciable deformation.
BROACHING- Multiple shaving, accomplished by pushing a tool with stepped cutting edges along the work, particularly through holes.
BUCKLE- Alternate bulges or hollows recurring along the length of the product with the edges remaining relatively flat.
BURR- A thin ridge or roughness left by a cutting operation such as in metal slitting, shearing, blanking or sawing. This is common to a
CALCIUM- (Chemical Symbol Ca) - A silvery white metal that is unstable in air. Compounds of calcium are used in steelmaking for fluxing impurities, desulfurizing, and/or inclusion shape control.
CALCIUM-SILICON TREATMENT- When used in conjunction with desulfurization, imparts inclusion shape control in killed steels.
CAMBER (BOW)- Edgewise curvature. A lateral departure of a side edge of sheet or strip metal from a straight line.
CAPPED STEEL- This is a type of steel with characteristics similar to those of rimmed steels, but to a degree intermediate between those of rimmed and semi killed steels. It can be either mechanically capped or chemically capped when the ingot is cast, but in either case the full rimming action is stopped, resulting in a more uniform composition than rimmed steel.
CARBIDE- A compound of carbon with one or more metallic elements.
CARBON- (Chemical Symbol C) - The most commonly used steel strengthening agent, carbon is present in practically all ferrous alloys and has tremendous effect on the properties of the resultant metal.
CARBON EDGE- Carbonaceous deposits in a wavy pattern along the edges of the sheet or coil.
CARBON POTENTIAL- A measure of the ability of an environment containing active carbon to maintain, under prescribed conditions, the carbon content of the steel exposed to it.
CARBON RANGE-In steel specifications, the carbon range is the difference between the minimum and maximum amount of carbon acceptable.
CARBON RESTORATION- Replacing the carbon lost in the surface layer from previous processing by carburizing this layer to substantially increase the original carbon level.
CARBONITRIDING- A case hardening process in which a suitable ferrous material is heated above the lower transformation temperature in a gaseous atmosphere of such composition as to cause simultaneous absorption of carbon and nitrogen by the surface and, by diffusion, create a concentration gradient. The process is completed by cooling at a rate which produces the desired properties in the workpiece.
CARBON STEEL- Steel is considered to be carbon steel when no minimum content is specified or required for chromium, cobalt, columbium (niobium), molybdenum, nickel, titanium, tungsten, vanadium or zirconium, or any other element added to obtain a desired alloying effect. When the specified minimum for copper does not exceed 0.40 percent or when the maximum content specified for any of the following elements does not exceed the percentages noted: manganese 1.65, silicon 0.60, copper 0.60.
CARBURIZING- Adding carbon to the surface of iron-base alloys by absorption through heating the metal at a temperature below its melting point in contact with carbonaceous solids, liquids or gases. The oldest method of case hardening.
CASE- In a ferrous alloy, the outer portion that has been made harder than the inner portion or core by CASE HARDENING.
CASE HARDENING- Carburizing and subsequently hardening by suitable heat-treatment, all or part of the surface portions of a piece of iron-base alloy.
CEMENTITE- A compound of iron and carbon known as 'iron carbide', which has the approximate chemical formula Fe3C containing 6.69% of carbon. Hard and brittle, it is the hard constituent of cast iron, and the normal form in which carbon is present in steel.
CHARPY V-NOTCH BAR- A standard, machined specimen used to determine impact strength.
CHATTER MARKS- Parallel indentations or marks appearing at right angles to edge of strip forming a pattern at close and regular intervals caused by roll vibrations.
CHECKED EDGES- Sawtooth edges seen after hot rolling and/or cold rolling.
CHEMICAL ANALYSIS- See CLASSICAL (WET) CHEMICAL ANALYSIS, COMBUSTION (LECO) CHEMICAL ANALYSIS, LADLE ANALYSIS, PRODUCT ANALYSIS and SPECTROMETRIC ANALYSIS.
CHROMIUM- (Chemical symbol Cr) - A bright, silvery colored, relatively hard metal used as an alloy in steelmaking to increase hardenability, strength, corrosion resistance, abrasion resistance and to reduce the tendency for graphite formation.
CLADDING- A process for covering one metal with another. Usually the surfaces of fairly thick slabs of two metals are brought carefully into contact and are then subjected to co-rolling so that a clad composition results. In some instances a thick electroplate may be deposited before rolling.
CLAD METAL- A composite metal containing two or three layers that have been bonded together. The bonding may have been accomplished by co-rolling, welding, heavy chemical deposition or heavy electroplating.
CLASSICAL (WET) CHEMICAL ANALYSIS- Specific methods used to determine one element per method, using chemical reactions unique to that element. Precipitation, oxidation -reduction or acid - base titration, colored complex formation, electrodeposition and reduction potential are among the techniques employed.
CLUSTER MILL- A rolling mill where each of the two working rolls of small diameter is supported by more than two back-up rolls.
COARSE GRAIN- Coarse FERRITIC grain manifests itself as a surface condition similar to an orange peel that is accompanied by very low hardness and a significant loss of ductility.
COARSE GRAIN PRACTICE- A steelmaking practice designed to promote a coarse AUSTENITE grain size by excluding grain refiners (primarily aluminum) from the steel composition. In general, coarse grain steels have a greater hardenability than comparable fine grained steels.
COIL SET OR LONGITUDINAL CURL- A lengthwise curve or set found in coiled strip metals following its coil pattern. A departure from longitudinal flatness. Can be removed by roller or stretcher leveling from metals in the softer temper ranges.
COINING- A process of impressing images or characters of the die and punch onto a metal surface.
COIL BREAKS- Creases or ridges appearing in sheets as parallel lines transverse to the direction of rolling and generally extending across the width of the sheet.
COILING TEMPERATURE- The temperature of hot rolled steel just prior to being wound into a coil; controlled by application of cooling water sprays as the strip travels down the runout table between the last finish mill stand and the coiler. Coiling temperature strongly influences as-hot rolled mechanical properties.
COIL WELD- A joint between two lengths of metal within a coil - not always visible in cold reduced product.
COLD REDUCED STRIP- Metal strip made from hot-rolled strip by rolling on cold-reduction mills.
COLD ROLLED FINISH- Finish obtained by cold rolling plain pickled sheet or strip with a lubricant resulting in an improved appearance.
COLD ROLLED SHEETS- A product produced from a hot rolled pickled coil which has been given substantial cold reduction at room temperature. The resulting product usually requires further processing to make it suitable for most common applications. The usual end product is characterized by improved surface, greater uniformity in thickness and improved mechanical properties compared to hot rolled sheet.
COLD ROLLING- Rolling metal at a temperature below the softening point of the metal to create strain hardening (work-hardening). Same as cold reduction, except that the working method is limited to rolling. Cold rolling changes the mechanical properties of strip and produces certain useful combinations of hardness, strength, stiffness, ductility and other characteristics known as tempers.
COLD SHUT- A defect produced during casting, causing 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, fuse or blend into a solid mass. (See Lamination.)
COLD WORKING- Plastic deformation, such as rolling, hammering, drawing, etc., at a temperature sufficiently low to create strainhardening (work-hardening).
COLUMBIUM- (Chemical Symbol Cb) - see NIOBIUM.
COMBUSTION (LECO) CHEMICAL ANALYSIS- Three thermal techniques are employed to determine interstitial elements.
*Carbon and/or Sulfur:A steel sample is heated inductively in an inert crucible in a stream of oxygen; the carbon and sulfur oxides are determined by infrared spectrometry, gas chromatography, or thermal conductivity.
*Nitrogen and/or Oxygen:A steel sample is heated inductively in a graphite crucible in a stream of an inert gas (Helium). Nitrogen and C02 are released and determined by one of the methods above.
*Hydrogen:A steel sample is heated below its fusion point, liberating hydrogen which is determined by thermal conductivity.
COMMERCIAL QUALITY STEEL SHEET- Normally made to a ladle analysis of carbon limit at 0.15 max. A standard quality carbon steel sheet.
CONTINUOUS CASTING- A casting technique in which semifinished steel (slabs, blooms, billets, bars, plates) is continuously produced directly from molten metal and length is not a function of mold dimensions.
CONTINUOUS ANNEALING- An annealing process consisting of uncoiling and passing the strip continuously through a furnace followed by cooling and recoiling. Since the cross section of steel heated at anyone time is small, it is possible to achieve much higher heating and cooling rates than with batch annealing. This feature is suited to the production of high strength product as well as closely controlled tempers. The intimate contact between steel and furnace atmosphere is also ideal for decarburization annealing. Since soak times in continuous annealing are short, the process is not well suited to cycles requiring time at temperature for diffusion such as deep draw quality and spheroidization annealing.
CONTINUOUS FURNACE -Furnace in which the material being heated moves steadily through the furnace.
CONTINUOUS STRIP MILL- A series of synchronized rolling mill stands in which coiled flat rolled metal entering the first pass (or stand) moves in a straight line and is continuously reduced in thickness (not width) at each subsequent pass. The finished strip is recoiled upon leaving the final or finishing pass.
CONTROLLED COOLING- Cooling from an elevated temperature in a predetermined manner, to avoid hardening, cracking, internal damage or to produce a desired microstructure or mechanical properties. The term applies to cooling following hot working.
COPPER- (Chemical symbol Cu) - A characteristically reddish metal of bright luster, highly malleable and ductile and having high electrical and heat conductivity. When alloyed with iron in sufficient concentration, it increases the metal corrosion resistance. Such steels are often identified by the term WEATHERING.
CORROSION- Gradual chemical or electrochemical attack on a metal by atmosphere, moisture or other agents.
CRITICAL COOLING RATE- The minimum rate of continuous cooling to prevent undesirable transformations. For steel it is the minimum rate at which austenite.must be continuously cooled to suppress transformations above the Ms temperature.
CRITICAL POINTS- Temperatures at which internal changes or transformations take place within a metal either on a rising or falling temperature.
CRITICAL RANGE- A temperature range in which an internal change takes place within a metal. Also termed transformation range.
CROP- The defective ends of a rolled or forged product which are cut off and discarded.
CROSS BREAK- See Luders Lines. This term is also applied to transverse ribs or ripple.
CROSSBOW- See DISH
CROWN OR HEAVY CENTER- Increased thickness in the center of metal sheet or strip as compared with thickness at the edge.
CRYSTAL- (1) A physically homogeneous solid in which the atoms, ions or molecules are arranged in a three-dimensional repetitive pattern. (2) A coherent piece of matter, all parts of which have the same anisotropic arrangement of atoms; in metals, usually synonymous with 'grain' and 'crystallite'.
CRYSTALLINE- Composed of crystals.
CRYSTALLIZATION- The formation of crystals by the atoms assuming definite positions in a crystal lattice. This is what happens when a liquid metal solidifies.
CUP TEST- (See Olsen Ductility Test.)
CUT EDGE- A mechanically sheared edge obtained by slitting, shearing, or blanking.
CYANIDING- A case hardening process in which a ferrous material is heated above the lower transformation range in a molten salt containing cyanide to cause simultaneous absorption of carbon and nitrogen at the surface and, by diffusion, create a concentration gradient. Quench hardening completes the process.
DEAD FLAT- Perfectly flat. As pertaining to sheet, strip or plate. Refer to STRETCHER LEVELING.
DEAD SOFT STEEL - Steel, normally made in the basic open-hearth furnace or by the basic oxygen process with carbon less than 0.10% and manganese in the 0.20% - 0.50% range, not temper rolled or leveled, annealed last.
DEAD SOFT TEMPER- (No.5 Temper) - Condition of maximum softness commercially attainable in wire, strip, or sheet metal in the annealed last condition.
DEBURRING- A method whereby the raw slit edge of metal is removed by rolling or filing.
DECARBURIZATION- Removal of carbon from the outer surface of iron or steel, usually by heating in an oxidizing atmosphere. Water vapor, oxygen and carbon dioxide are strong decarburizers. Reheating with adhering scale is also strongly decarburizing in action.
DECARBURIZATION ANNEALING- Exposure to an oxidizing atmosphere during annealing to remove carbon from the strip. In batch annealing, contact between steel and atmosphere is usually accomplished by inserting spacers between laps of coils, a process known as OPEN COIL ANNEALING.
DEEP DRAWING- The process of cold working or drawing sheet or strip metal blanks by means of dies on a press into shapes which are usually more or less cup-like in character involving considerable plastic deformation of the metal. Deep-drawing quality sheet or strip steel, ordered or sold on the basis of suitability for deep-drawing.
DEGASSING PROCESS- Removing gases and carbon from the molten metal by means of a vacuum process in combination with mechanical action.
DELTA r (r)- Variation in strain ratio with direction, an index of a steel's tendency to ear, or form scallops, in a deep draw. A value of zero indicates the material is NONSCALLOPING, while positive values indicate ears will form along and transverse to the rolling direction and negative values indicate ears will form at 45 degrees to the rolling direction.
DEOXIDIZING- Removal of oxygen.
DISH- Degree of concavity/convexity across the width of the strip from edge to edge.
DRAWING BACK- A misnomer for TEMPERING; consists of heating after hardening to a temperature below the lower critical temperature to change hardness and increase impact strength.
EARING- Wavy projections formed at the open end of a cup or shell rim in the course of deep drawing because of differences in directional properties. Also termed scalloping. See NONSCALLOPING.
EDGE FILING -A method whereby the raw or slit edges of strip metal are passed or drawn one or more times against a series of files, mounted at various angles. This method may be used for deburring only or filing to a specific contour including a completely rounded edge.
EDGE STRAIN OR EDGE BREAKS- Creases extending in from the edge of the temper rolled sheet.
EDGEWISE CURVATURE- (See CAMBER.)
EDGING- The dressing of metal strip edges by rolling, filing or drawing.
ELASTIC LIMIT- Maximum stress that a material will stand before permanent plastic deformation occurs.
ELECTRIC FURNACE STEEL- Steel made in any furnace where heat is generated electrically, almost always by arc.
ELECTRO-GALVANIZING- Galvanizing by electro deposition of zinc on steel.
ELECTROLYTIC TIN PLATE- BLACK PLATE that has been tin plated on both sides with commercially pure tin by electrode position (refer TIN PLATING).
ELECTROPLATING- The production of a thin coating of one metal on another by electro-deposition.
ELONGATION- As it pertains to the TENSILE TEST, the increase in length which occurs before the metal is fractured, when subjected to stress. This is usually expressed as a percentage of the original length and is a measure of the ductility of the metal. In SKIN PASS or TEMPER ROLLING, the increase in length of the material resulting from cold rolling, expressed as a percentage.
EMBOSSING- Raising or indenting a design in relief on a sheet or strip of metal by passing between rolls of desired pattern.
ENDURANCE LIMIT- Maximum alternating stress which a given material will withstand for an indefinite number of times without causing fatigue failure.
ENTRY MARK- A slight corrugation caused by the entry rolls of a roller leveling unit.
ERICHSEN TEST- Similar to the OLSEN TEST. Readings are in millimeters.
ETCHING- In metallography, the process of revealing structural details by the preferential attack of reagents on a metal surface.
EXTENSOMETER- An apparatus for indicating the deformation of metal, especially elongation, while it is subjected to stress.
FATIGUE- The phenomenon leading to fracture under repeated or fluctuating stress. Fatigue fractures are progressive, beginning as minute cracks and growing under the action of fluctuating stress.
FERRITE- The soft ductile almost pure iron phase that, together with the carbide phases, makes up the microstructure of steel at temperatures below the critical (1333°F).
FINISHES- The surface appearance of the various metals after final treatment such as rolling. etc. Over the years the following finishes have become recognized as standard in their respective fields.
Dull Finish - a finish without luster produced by use of roughened rolls.
Bright Finish - a luster finish produced by use of rolls having a moderately smooth surface.
2.COLD ROLLED STEEL SHEETS
Commercial Finish - A dull satin surface texture produced by roughened rolls.
Commercial Bright Finish - Bright in appearance with a texture between luster and a very fine matte finish.
Luster Finish - Produced by use of ground and polished rolls. (Note - This is not a number 3 finish.)
3.COLD ROLLED STRIP STEELS
No. 1 Finish - A dull finish produced without luster by rolling on roughened rolls.
No. 2 Finish - A regular bright finish produced by rolling on moderately bright rolls.
No. 3 Finish - Best Bright Finish - A lustrous or high gloss finish produced by rolling on highly polished rolls - Also referred to as Mirror Finish.
Bright hot dipped finish.
Electro Matte Dull Finish.
Electro Bright Reflow Finish - produced by the in-the-line thermal treatment following electrodeposition.
FINISHING TEMPERATURE- The temperature at which final hot working is done. It is usually understood to be the steel temperature at the exit side of the last rolling stand of the hot strip mill.
FLAME ANNEALING- A process of softening a metal by the application of heat from a high temperature flame.
FLAT WIRE- A flat cold rolled, prepared edge section up to 1V4"wide, rectangular in shape. Generally produced from hot rolled rods or specially prepared round wire by one or more cold rolling operations, primarily for the purpose of obtaining the size and section desired. May also be produced by slitting cold rolled flat metal to desired width followed by edge dressing.
FLOPPERS- Lines or ridges which are transverse to the direction of rolling and generally confined to the section midway between the edges of the coil as rolled. They are somewhat irregular and tend toward a flat arc shape.
FLUTING- Kinking or breakage due to curving of metal strip on a radius so small, with relation to thickness, as to stretch the outer surface above its elastic limit.
GAGES- (Metal) - Manufacturers' standard numbering systems indicating decimal thicknesses or diameters.
GALLING- The damaging of one or both metallic surfaces by removal of particles from localized areas due to seizure during sliding friction.
GALVANIZING- Coating steel with zinc and tin (principally zinc) for rustproofing purposes. Formerly for the purpose of galvanizing, cut length steel sheets were passed singly through a bath of the molten metal. Today's galvanizing processing method consists of uncoiling and passing the continuous length of successive coils either through a molten bath of the metal (termed Hot Dipped Galvanizing) or by continuously zinc coating the uncoiled sheet electrolytically (termed ELECTRO-GALVANIZING).
GALVANNEALED COATING- Galvannealed sheets are hot dipped zinc-coated sheets which have been processed to produce a zinc-iron alloy coating. This product does not have a spangle and is suitable for painting after cleaning. The alloy produced lacks ductility and powdering of the coating can occur during forming.
GHOST LINES (GHOST WELT LINES)- Lines running parallel to the rolling direction that appear in a panel when it is stretched. These lines may not be evident unless panel has been sanded or painted. (Not to be confused with leveler lines.)
GRAIN- A solid polyhedral (many sided) crystal 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 direction of rolling.
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.
GRAIN GROWTH- The increase in average steel grain size that accompanies heating to or slow cooling from elevated temperature.
GRAIN SIZE- The average diameter of grains of metal or, alternately, the number of grains per unit volume. In ferrite (room temperature), an increase in grain size lowers hardness but may also decrease ductility and impact resistance. In austenite, an increase in grain size increases hardenability.
GRAIN REFINEMENT- A technique of increasing the strength of steel by reducing the size of its constituent grains, usually through the addition of grain refining alloys such as niobium, vanadium, and/or aluminum.
GRAPHITIZING- Annealing a ferrous alloy in such a way that some or all of the carbon is precipitated as graphite.
HALF HARD TEMPER- (No.2 Temper.) - In low carbon cold-rolled strip steel, produced by cold rolling to a hardness near to but somewhat softer than full hard temper.
HARDENABILITY- A property that indexes the depth and distribution of hardness induced by quenching from a suitable tem.perature. (See JOMINY HARDENABILITY TEST)
HARDENED AND TEMPERED SPRING STEEL STRIP- A medium or high carbon quality steel strip which has been subjected to the processing sequence of heating, quenching and tempering.
HARDENING- Any thermal process which increases the hardness of a metal. Usually heating and quenching certain iron base alloys from a temperature either within or above the critical temperature range.
HARDNESS- Degree to which a metal will resist cutting, abrasion, penetration, bending and stretching. The indicated hardness of metals will differ somewhat with the specific apparatus and technique of measuring. For details concerning the various types of apparatus used in measuring hardness; See BRINELL HARDNESS, ROCKWELL HARDNESS, VICKERS HARDNESS, SCLEROSCOPE HARDNESS. TENSILE STRENGTH also is an indication of hardness.
HEALED OVER SCRATCH- A scratch that occurred in an earlier mill operation and was partially masked in subsequent rolling. It may open up during forming.
HEAT OF STEEL- The product of a single batch melting operation in a furnace, starting with the charging of raw materials and ending with the tapping of molten metal.
HEAT TREATMENT- Altering the properties of a metal by subjecting it to a sequence of temperature changes, time of retention at specific temperature and rate of cooling there from being as important as the temperature itself. Heat treatment usually markedly affects strength, hardness, ductility, malleability and similar properties of both metals and their alloys.
HSLA - (HIGH STRENGTH LOW ALLOY)- Comprises a specific group of steels with chemical composition specially developed to impart higher mechanical property values and, in certain of these steels, greater resistance to atmospheric corrosion than is obtainable from conventional carbon structural steels. High strength low alloy steel is generally produced with emphasis on mechanical property requirements rather than to chemical composition limits. It is not considered to be alloy steel.
HOT DIP- In steel mill practice. a process whereby ferrous alloy base metals are dipped into molten metal, usually zinc, tin, aluminum or terne, for the purpose of fixing a corrosion resistant coating.
HOT ROLLED- Hot rolled sheets are those that are reduced to required thickness at temperatures at which scale is formed and, therefore, carry hot mill oxide.
HOT ROLLED PICKLED- The hot rolled product which has been treated to remove the hot mill oxide.
HOT WORKING- Plastic deformation of metal at a temperature sufficiently high not to create strain hardening. The lower limit of temperature for this process is the recrystallization temperature.
INCLUSIONS- Particles of impurities (usually oxides, sulfides. silicates, etc.) that are held mechanically or are formed during the solidification or by subsequent reaction within the solid metal.
INCLUSION SHAPE CONTROL- Processing of molten metal to produce a product with reduced levels of linear ('Stringer') type inclusions resulting in improved formability and impact strength in the final product. Desulfurization, calcium-silicon treatment and addition of other strong deoxidizers, such as zirconium, are methods generally employed.
INDENTATION HARDNESS- The resistance of a material to indentation. This is the usual type of hardness test, in which a pointed or rounded indenture is pressed into a surface under a substantially static load.
INDUCTION HARDENING- A surface hardening process in which only the surface layer of suitable ferrous workpiece is heated by electrical induction to above the upper transformation temperature and immediately quenched.
INDUCTION HEATING- Heating by electrical induction.
INGOT- A casting for subsequent rolling or forging.
INHIBITOR- A substance which retards some specific chemical reaction. Pickling inhibitors retard the dissolution of metal without hindering the removal of scale from steel.
INTERLEAVING- The placing of a sheet of paper between two adjacent layers of metal to facilitate handling and shearing of rectangular sheets, or to prevent sticking or scratching.
INTERMEDIATE ANNEALING- An annealing treatment given to wrought metals following cold work hardening for the purpose of softening prior to further cold working. (See PROCESS ANNEALING.)
INTERRUPTED QUENCHING- A quenching procedure in which the workpiece is removed from the first quench at a temperature substantially higher than that of the quenchant and is then subjected to a second quenching system having a different cooling rate than the first.
INTERSTITIAL FREE (I.F.) STEEL- Ultra low carbon, aluminum killed, titanium, and/or columbium stabilized cold rolled steel. A nonaging, superior deep drawing grade that exhibits no yield point elongation. Not recommended for parts that are drawn without hold down or flanges in the drawing dies.
IRON- (Chemical Symbol Fe) - A magnetic silver - white metal of high tensile strength and ductility. Principal commercial forms are steel, cast iron, and wrought iron.
IRONING- Thinning the walls of deep drawn parts by reducing clearance between punch and die.
ISOTHERMAL ANNEALING- Austenitizing a ferrous alloy and then cooling to and holding at a temperature at which austenite transforms to a relatively soft ferrite-carbide aggregate.
ISOTHERMAL TRANSFORMATION- A change in phase at constant temperature.
JOMINY HARDENABILITY TEST- A test to determine the heat treat response of steel. A standard sample bar (preferably forged) is heated to a suitable temperature, placed in a fixture, and quenched by spraying water on one end only. Since the cooling rate decreases as distance from the quenched end increases, hardness values taken at intervals from the quenched end may be plotted to determine the depth of hardness that may be obtained with a given quench rate.
KILLED- The term 'killed' indicates that the steel has been sufficiently deoxidized to suppress gas evolution from the molten metal as it solidifies. The general practice is to use aluminum, ferrosilicon or manganese as deoxidizing agents. A properly killed steel is more uniform as to analysis and is comparatively free from aging. However, for the same carbon and manganese content killed steel is harder than rimmed steel. In general, all steels above 0.25% carbon are killed; also all forging grades, structural steels from 0.15% to 0.25% carbon and all continuously cast steels.
LADLE ANALYSIS- A term applied to the chemical analysis representative of a heat of steel as reported by the producer. It is determined by analyzing a rapidly cooled (to minimize chemical segregation) test sample obtained during the pouring of the steel.
LAMINATIONS- A defect that appears in flat rolled steel as layers or as segregation, LAMINATIONS can occur at the surface (SCABS, SLIVERS) or in the interior of the steel cross section (PRIMARY PIPE).
LAMINATIONS, MOTOR- A specialized steel application requiring specific electrical properties and/or hardness and punchability characteristics. Motor Lamination steels are often specified to detailed public (ex:ASTM A726) and/or proprietary specifications.
LAP- A surface defect appearing as a seam, caused by folding over hot metal, fins or sharp corners and then rolling or forging them into the surface, but not welding them.
LATTICE- Space lattice. Lattice lines and lattice planes are lines and planes chosen so as to pass through collinear lattice points, and non-collinear lattice points, respectively.
L.D.H. TEST (LIMITING DOME HEIGHT)- A test for evaluating sheet metal formability in which a series of specimens of varying widths are stretched by a 100mm spherical punch until fractures occur. The height of the dome at fracture of the narrowest width specimen that may be drawn without a decrease in specimen width is the limiting dome height. The test may be tailored to predict a steel's press performance when stretch-drawing is the primary forming mode.
LECO CHEMICAL ANALYSIS- See COMBUSTION CHEMICAL ANALYSIS.
LEVELING- Flattening rolled metal sheet or strip (See ROLLER and STRETCHER LEVELING).
LONG TERNE- A term applying to steel sheets that have been teme coated (LEAD AND TIN) by immersion in a bath of Terne Metal (See TERNE PLATE).
LOOSE METAL- Refers to an area of a panel that is not stiff enough to hold its shape.
LOW CARBON STEEL- Contains approximately .30 max carbon and .60 max manganese.
LUDERS LINES- Long crosshatch marks appearing on the surface of certain metals, in the direction of the maximum shear stress, when the metal is subjected to deformation beyond the yield point. Also called STRETCHER STRAINS.
LUSTER FINISH- A finish produced on ground rolls suitable for decorative painting and plating with additional surface preparation after forming.
MATTE FINISH- The texture produced on sheets by rolls which have been blasted to various degrees of roughness depending upon the end use.
MACRO ETCH TEST- Consists of immersing a carefully prepared section in hot acid and then examining the etched surface to evaluate the soundness' and homogeneity of the product being tested.
MACROGRAPH- A photographic reproduction of any object that has not been magnified more than ten times.
MACROSCOPIC- Visible either with the naked eye or under low magnification (as great as about ten diameters).
MACROSTRUCTURE- The structure of metal as revealed by macroscopic examination.
MALLEABILITY- The property that determines the ease of deforming a metal when the metal is subjected to rolling or hammering. The more malleable metals can be hammered or rolled into thin sheet more easily than others.
MANGANESE- (Chemical Symbol Mn) - A lustrous, reddish-white hard, brittle metal whose principal function is as an alloy in steelmaking. It inhibits embrittlement caused by sulfur, acts as a ferrite strengthener and carbide former and tends to increase hardenability.
MARTEMPERING- (1) A hardening procedure in which an austenitized ferrous workpiece is quenched into an appropriate medium whose temperature is maintained substantially at the Ms of the workpiece, held in the medium until its temperature is uniform throughout but not long enough to permit bainite to form and then cooled in air. The treatment is frequently followed by tempering. (2) When the process is applied to carburized material, the controlling Ms temperature is that of the case. This variation of process is frequently called marquenching.
MARTENSITE RANGE- The temperature interval between Ms and MI. MI- Defined under TRANSFORMATION TEMPERATURE. Ms - Defined under TRANSFORMATION TEMPERATURE.
MARTENSITE- A distinctive, needlelike microstructure produced by rapid cooling of austenite at a rate sufficient to prevent pearlite formation. Martensite is a very hard and brittle phase that is almost always tempered to impart some limited amount of impact strength.
MECHANICAL PROPERTIES- The properties of a material that reveal its elastic and plastic behavior when force is applied, for example, yield strength, ultimate tensile strength, elongation, hardness, etc.
MECHANICAL WORKING- Plastic deformation or other physical change to which metal is subjected, by rolling, hammering, drawing, etc. to change its shape, properties or structure.
METALLOGRAPHY- The science concerning the constituents and structure of metals and alloys as revealed by microscope.
MOLYBDENUM- (Chemical symbol Mo) - A hard. tough metal of grayish-white color, becoming very ductile and malleable when properly treated at high temperatures. Its principal function is as an alloy in steel making: (1) Raises grain-coarsening temperature of austenite. (2) Deepens hardening. (3) Counteracts tendency toward temper brittleness. (4) Raises hot creep strength, red hardness.
MICROSTRUCTURE- The structure of polished and etched metal and alloy specimens as revealed by microscope.
MILL EDGE- The normal edge produced in hot rolling. This edge is customarily removed when hot rolled sheets are further processed.
MINIMIZED SPANGLE- Minimized spangle galvanized sheet has very small spangles which are obtained by' treating the galvanized sheet during the solidification of the zinc to restrict the normal zinc spangle formation.
NATURAL AGING- Spontaneous aging of a supersaturated solid solution at room temperature.
NECKING- Reducing the thickness of a sheet in a localized area by stretching.
NETWORK STRUCTURE- A structure in which the crystals of one constituent are surrounded by envelopes of another constituent which gives a network appearance to an etched test specimen.
NICKEL- (Chemical symbol Ni) - Silvery white, slightly magnetic metal, of medium hardness and high degree of ductility and malleability and resistance to chemical and atmospheric corrosion. Used as an alloying agent, it is of great importance in iron-base alloys, in stainless steels and in copper-base alloys such as Cupro-Nickel, as well as in nickel-base alloys such as Monel Metal. Its principal functions as an alloy in steel making: (1) Strengthens unquenched or annealed steels. (2) Toughens pearlitic-ferritic steels (especially at low temperature). (3) Renders high-chromium iron alloys austenitic.
NIOBIUM- (Chemical Symbol Nb) - A steel gray, lustrous metal that is frequently used as a grain refining strengthener in high strength low alloy steel. It is sometimes called COLUMBIUM.
NITRIDING- Process of surface hardening certain types of steel by heating in ammonia gas at about 935 - 1OOO°F., the increase in hardness being the result of surface nitride formation. Certain alloying constituents, principal among them being aluminum, greatly facilitate the hardening reaction. In general, the depth of the case is less than with carburizing.
NON-METALLIC INCLUSIONS- Impurities (commonly oxides). sulfides, silicates or similar substances held in metals mechanically during solidification or formed by reactions in the solid state.
NONSCALLOPING- (Non-Earing) Absence of the tendency for steel to form scallops or ears (marked unevenness) around the top edge of a drawn cup; caused by differences in directional properties of the metal.
OFFAL- The material trimmed from blanks or formed panels.
OIL CAN (OIL CANNING)- Refers to an area in a formed panel that when depressed slightly will recover its original contour after the depressing force is removed.
OLSEN (DUCTILITY) TEST- A method of measuring the ductility and drawing properties of strip or sheet metal which involves determination of the width and depth of impression. The test, simulating a drawing operation, is made by a standard steel ball under pressure, continuing until the cup formed from the metal sample fractures. The height of the cup at fracture is read in thousandths of an inch. This test is sometimes used to detect stretcher straining and coarse grain and indicates the surface finish after drawing, similar to the ERICHSEN ductility test.
OPEN COIL ANNEALING -A BATCH ANNEAL process where adjacent coil laps are separated by wire spacers prior to annealing permitting complete exposure of the steel surface to the anneal atmosphere speeding up heating and cooling and promoting a more uniform heat distribution. Often used with an oxidizing atmosphere to produce decarburized steel products.
ORANGE PEEL- (effect) - A surface roughening (defect) encountered in forming products from metal stock that has a coarse grain size. It is due to uneven flow or to the appearance of the overly large grains usually the result of annealing at too high a temperature. Also referred to as ”pebbles" and "alligator skin".
OSCILLATED WOUND OR SCROLL WOUND- A method of even winding metal strip or wire onto a reel or mandrel wherein the strands are uniformly over-lapped. Sometimes termed "stagger wound" or "vibrated wound". The opposite of RIBBON WOUND.
PARALLELISM- The maximum thickness variation on a line perpendicular to the rolling direction across the strip width, but no closer than 3/8" to the edges.
PATTERNED OR EMBOSSED SHEET- A sheet product on which a raised or indented pattern has been impressed on either one or both surfaces by the use of rolls.
PEARLITE- Lamellar micro structure resembling mother of pearl. A compound of iron and carbon occurring in steel as a result of the transformation of austenite into aggregations of ferrite and iron carbide.
PHOSPHORUS- (Chemical Symbol P) - A nonmetallic element that is usually undesirable in steel. When added as an alloy, it is used as either a low cost strengthener in low carbon steel or to enhance machinability.
PHOTOMICROGRAPH- A photographic reproduction of any object magnified more than ten diameters.
PHYSICAL PROPERTIES- Those properties familiarly discussed in physics, exclusive of those defined as mechanical properties; for example; density, electrical conductivity, co-efficient of thermal expansion. This term often has been used to describe mechanical properties, but this usage is not recommended. (See MECHANICAL PROPERTIES.)
PICKLING- The process of chemically removing oxides and scale from the surface of a metal by the action of water solutions of inorganic acids.
PICKLING PATCH- A defect attributable to faulty pickling leaving areas from which the oxide has not been completely removed.
PICKLE STAIN- Discoloration present after pickling.
PICKUP- Metal particles adhering to a work roll or tool which cause a series of dents, scratches, or pits on a sheet or part.
PIG IRON-Iron produced by reduction of iron ore in a blast furnace. Pig iron contains approximately 92% iron and about 3.5% carbon. The balance is largely silicon and manganese with small percentages of phosphorus, sulphur and other impurities.
PINCHERS- Long fern like, chevron creases usually diagonal to the direction of rolling.
PINHOLES- Microscopic imperfections in coatings, (microscopic bare spots); also microscopic holes penetrating through a layer or thickness of light gage metal.
PIPE- Shrinkage cavity, essentially inverted cone-like in shape, which occurs in the approximate center, at the top and reaching down into a casting; caused by the shrinkage of cast metal upon solidification.
PIT- A sharp depression in the surface of the metal.
PRIMES- Metal products, such as sheet and plate. of the highest quality and free from visible surface defects.
PROCESS ANNEALING- In the sheet and wire industries, a process by which a ferrous alloy is heated to a temperature close to, but below, the lower limit of the transformation range and is subsequently cooled. This process is applied in order to soften the alloy for further cold working.
PRODUCT ANALYSIS- Chemical analysis as determined from a sample taken from the finished steel product. Since it is subject to segregation, it is not as representative as the LADLE ANALYSIS.
PROFILOMETER- A testing instrument that measures SURFACE TEXTURE.
PUNCH- The moveable male part that forces the metal into the female die in equipment for sheet drawing, blanking, coining, emhossing and the like.
PUNCHING- Shearing holes in sheet metal with punch and die.
PYROMETER- An instrument used for measuring elevated temperatures.
QUARTER HARD- (No.3 Temper) - In low carbon cold-rolled strip steel, a medium soft temper produced by a limited amount of cold rolling after annealing.
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 in oil, water, or molten salt.
QUENCH HARDENING- A process of hardening a ferrous alloy of suitable composition by heating within or above the transformation range and cooling at a rate sufficient to increase the hardness substantially. The process usually involves the formation of martensite.
RADIANT TUBE ANNEALING BOX- A box which is heated inside by means of tubes in which gas is burned; the hot tubes radiate their heat to the inner covered stack of metal, standing on the base of the box. Usually a protective atmosphere is maintained in the inner cover to protect the metal from oxidation.
R-BAR (r)- The average STRAIN RATIO, an index of sheet steel resistance to thinning (drawability) during deep drawing. Normally associated with aluminum killed, drawing Quality cold rolled products, an r of 1.0 indicates equal flow strength in all directions while higher values indicate greater resistance to thinning through the cross section than to flow down the plane of the sheet. "Good" AK DQ cold rolled sheet steel typically will exhibit r values in the range of 1.4 - 2.2.
RECOVERY- The first stage of annealing, cold reduced steel recovery is the relief of localized stresses induced by cold rolling. It occurs at relatively low temperatures.
RECOVERY ANNEALING- A low temperature annealing process designed to impart limited ductility to full hard cold reduced steel without substantially altering as-rolled strength or microstructure.
RECRYSTALLIZATION- The second stage of annealing cold reduced steel, recrystallization is the replacement of the highly stressed cold worked grain structure by new. virtually stress free-grains. The process is accomplished by annealing above a specific temperature for a specific time.
RECRYSTALLIZATION TEMPERATURE- The approximate minimum temperature at which complete recrystallization of a cold worked metal occurs within a specified time.
REEL BREAKS (REEL KINKS)- Transverse breaks or ridges on successive inner laps of a coil which are the result of crimping the lead end of the coil into a gripping segmented mandrel.
REPHOSPHORIZING- Addition of phosphorus to steel to increase strength punchability and machinability.
RESIDUALS- Incidental or "tramp" elements that are not specified but are included into steel from raw materials and refractories used in steelmaking.
RESISTANCE WELDING- A type of welding process in which the work pieces are heated by the passage of an electric current through the area of contact. Such processes include spot welding, seam or line welding and percussion welding. Flash and butt welding are sometimes considered as resistance welding processes.
RIDGE- A longitudinal line where the thickness of the metal is slightly greater than the thickness adjacent.
RIBBON WOUND -A term applied to a common method of winding strip steel layer upon layer around an arbor or mandrel.
RIMMED STEEL- A low carbon steel in which incomplete deoxidation results in the evolution of gas from the molten metal in the ingot mold. When poured into a bottle top mold, the steel material is called CAPPED STEEL. RIMMED STEEL is poured into open top molds.
RIM ZONE- The surface layers of capped and rimmed steels that are lower in carbon and other impurities (due to segregation) and also sounder than the core.
ROCKWELL HARDNESS (TEST)- A standard method for measuring the hardness of metals. The hardness is expressed as a number related to the depth of residual penetration of a steel ball or diamond cone ("brale") after a minor load of 10 kilograms has 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 by letters varying from "A" to "H"; the "B" and "C" scales are most commonly in use.
ROLLED IN SCALE- Surface imperfections caused by rolling un-removed iron oxide scale into the steel surface during hot rolling.
ROLLER LEVELER- A series of small diameter staggered rolls used primarily to improve flatness and/or to remove yield point elongation.
ROLLER LEVELER BREAKS- Obvious transverse breaks usually 1/8 to 1/4 inches apart caused by the sheet fluting during roller leveling. These will not be removed by stretching.
ROLLER LEVELER LINES- lines running transverse to the direction of leveling. These may be seen upon stoning or light sanding after leveling and before drawing. Moderate stretching will usually remove them.
S.A.E.- Abbreviation for Society of Automotive Engineers, an organization that originates many specifications pertaining to steel requirements and testing.
SCARFING- Removal of the surface layer of steel (and the surface defects therein) by using acetylene gas cutting torches. In steelmaking, this is usually done to slabs, blooms, billets or other semifinished steel products.
SCAB- Elongated patches of loosened metal that have been rolled into the steel surface.
SCALE- Oxides of iron that form on the surface of steel at elevated temperature.
SCLEROSCOPE HARDNESS (TEST)- A method for measuring the hardness of metals; a diamond-pointed hammer is dropped from a fixed distance through a tube onto the smoothed metal surface and the rebound is measured. The scleroscope hardness value is empirically taken from the rebound distance, with a specified high-carbon steel as 100.
SEAMS- Open, broken surface running in lines parallel to the rolling direction caused by subsurface inclusions or oxidized ingot/slab cracks.
SEGREGATION- The non-uniformity in chemical composition resulting from natural phenomena in the solidification of a steel ingot. The various elements of the steel have greater solubility in liquid steel than in solid steel, thus, they are concentrated in parts of the ingot last to solidify. Segregation in varying degrees is found in all types of steel.
SEMIFINISHED STEEL- Steel in the form of billets, blooms, etc., requiring further working before completion into finished steel ready for marketing.
SEMIKILLED STEEL- Steel that is partially deoxidized so that there is greater degree of gas evolution than in killed steel, but less than in capped or rimmed steel. The uniformity in composition lies between that of killed steel and rimmed steel.
SILICON- (Chemical Symbol Si) - An extremely common element used as a deoxidizer in steelmaking.
SILICON STEEL- Steel usually made in the electric furnace with about 0.50-5.0% silicon, other elements being usually kept as low as possible. Because of high electrical resistance and low hysteresis loss, silicon sheet and strip are standard in electric magnet manufacture.
SKELP- A plate of steel or wrought iron from which pipe or tubing is made by rolling the skelp into shape longitudinally and welding or riveting the edges together.
SKIN LAMINATION- Subsurface separation which usually results in surface rupture.
SKIN PASS- A light percentage reduction cold rolling given to steel to obtain final dimensional, physical and/or mechanical properties. Synonymous with TEMPER PASS.
SLAG- A product resulting from the action of a flux on the nonmetallic constituents of a molten metal bath, or on the oxidized metallic constituents that are undesirable.
SLITTING- Cutting steel to width continuously using rotary knives.
SLIVERS- Surface ruptures similar to skin laminations, but usually more pronounced.
SMUT- A reaction product sometimes left on the surface of the sheet after pickling or annealing.
SNAKY EDGES- Carbonaceous deposits in a wavy pattern along the edges of the annealed strip.
SOAKING- Prolonged heating of a metal at selected temperature.
SOFT SKIN ROLLED TEMPER- (No.4 Temper) - In low carbon-rolled strip steel, soft and ductile. Produced by subjecting annealed strip to a pinch pass or skin rolling (a very light rolling).
SPANGLE- The characteristic crystalline form in which the hot dipped zinc coating solidifies on steel strip.
SPECTROMETRIC CHEMICAL ANALYSIS- Used to determine quantitatively most alloying and residual elements in steel. It is a comparison method based upon a group of steel standards, each having a certified amount of one or more elements. Visible and ultraviolet light, emitted as discrete wavelengths by each element upon excitation by an electrical discharge, is detected in the spectrometer; the signal from each element is converted mathematically into a percent.
SPHEROIDIZING- Heating and cooling to produce a spheroidal or globular form of carbide in steel. Spheroidizing methods frequently used are:
1. Prolonged holding at a temperature just below Ae1'
2. Heating and cooling alternately between temperatures that are just above and just below Ae1'
3. Heating to a temperature above Ae1 or Ae3 and then cooling very slowly in the furnace or holding at a temperature just below Ae1'
SPINNING- The shaping of flat circular blanks by forcing the blank against a chuck or form block while it is rotating.
SPRINGBACK- The tendency of metal to partially return to its original shape after cold forming.
SPRING STEEL STRIP- Any of a number of strip steels produced for use in the manufacture of steel springs or where high tensile properties are required; it is marketed in the annealed state, hard rolled or as hardened and tempered strip.
STAMPING- A term used to refer to various press forming operations (blanking, coining, embossing, etc.) or to the product of those operations.
STEEL- Iron with small amounts of carbon added. Although other alloying elements may be present in significant quantities, most steels contain at least small amounts of manganese and, as undesirable residual constituents, sulfur and phosphorus.
STICKER- Adherences of adjacent laps or sheets of steel usually caused by fusion during annealing.
STRAIN- Deformation produced on a body by an outside force.
STRAIN HARDENING- An increase in hardness and strength caused by plastic deformation at temperatures lower than the recrystallization temperature.
STRAIN HARDENING EXPONENT- A measure of the rate of strain hardening. The constant 'n' in the expression rf = KEn where:
rf = True stress
K = Constant in the equation
E = True strain
n = Strain hardening exponent
The 'n' value is a measure of stretch formability. The higher the 'n' value, the better the stretch formability.
STRAIN RATIO- The ratio of width to thickness strain determined in the uniform elongation portion of a tension test. It is a good measure of the crystallographic directionality of the material. It is also a good measure of deep drawability. The higher the' r' value, the better the deep drawability.
STRETCHABILITY- The ability of a metal to be stretched over a punch without splitting.
STRETCH FORMING- Shaping of a sheet or part, usually of uniform cross section, by applying suitable tension or stretch and forming it around or over a die of the desired shape.
STRETCHING- The operation where the blank is stretched around the punch with no metal flow over the draw ring. The metal thickness is reduced.
STRETCHER LEVELING- A method of making metal flat by stretching beyond the yield point either between grippers (sheets) or rolls (coils).
STRETCHER STRAINS (LUDERS LINES)- Long vein-like marks appearing on the surface of certain metals, in the direction of the maximum shear stress, when the metal is subjected to deformation beyond the yield point.
STRIP STEEL- Flat steel products less than 24 inches wide and less than .250 inches thick.
SULFUR- (Chemical Symbol S) - Nonmetal occurring most commonly as a pale yellow, brittle solid. Although usually considered an unwanted impurity in steel, it is sometimes added deliberately to enhance machinability.
SURFACE TEXTURE- The finish of the surface of sheet steel presently described by the roughness (peak) height in micro inches and the peaks per inch.
TANDEM MILL- Arrangement of cold rolling mills in a direct line allowing metal to pass from one set of rolls to the next and be in all of the mills simultaneously.
TAPPING- Transfer of molten steel from melting furnace to a ladle.
TELESCOPING- Transverse slipping of successive layers of a coil so that the edge of the coil is irregular rather than flat.
TEMPERING- (Also termed 'drawing') -A process of reheating quench-hardened or normalized steel to 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 the steel to alleviate the brittleness of martensite.
TEMPER ROLLING- Light cold rolling of sheet steel. This operation is performed to improve flatness, minimize the tendency to stretcher strain and flute, and obtain the desired texture and mechanical properties.
TENSILE STRENGTH- The unit stress at the highest load reached during the tension test.
TENSILE TEST- A test for determining mechanical properties involving placing a standard test specimen in the jaws of a testing machine that records the elongation of the sample for increasing loading up to fracture. Properties determined include YIELD STRENGTH, TENSILE STRENGTH, ELONGATION, and STRAIN HARDENING EXPONENT.
TERNE PLATE- Sheet steel coated with an alloy of lead and less than 10% tin.
TIN- (Chemical Symbol Sn) - Soft silvery white metal of high malleability and ductility but low tensile strength. Used as a coating on steel or as an alloy of coating on steel.
TIN PLATE BASE BOX- A Tin Plate Base Box is measured in terms of pounds per Base Box (112 sheets 14" x 20"), a unit peculiar to the tin industry. This corresponds to an area of sheet totaling 31.360 square inches of any gage and is applied to tin plate weighing from 55 to 275 pounds per base box. To convert to decimal thickness multiply weight per base box by .00011.
TITANIUM- (Chemical Symbol Ti) - Bright white metal used in steelmaking as a carbide former that strengthens steel. Also used to protect BORON from nitrogen degradation in boron bearing heat treatable steels.
TITANIUM STABILIZED, VACUUM DEGASSED STEEL- Another name for INTERSTITIAL FREE STEEL popular in Europe and the far east.
TOUGHNESS- Property of resisting fracture or distortion. Usually measured by IMPACT TEST.
TRANSFORMATION RANGES OR TRANSFORMATION TEMPERATURE RANGES- Those ranges of temperature within which austenite forms during heating and transforms during cooling. The two ranges are distinct, sometimes overlapping but never coinciding. The limiting temperatures of the ranges depend on the composition of the alloy and on the rate of change of temperature, particularly during cooling. See TRANSFORMATION TEMPERATURE.
TRANSFORMATION TEMPERATURE -The temperature at which a change in phase occurs. The term is sometimes used to denote the limiting temperature of a transformation range. The following symbols are used for iron and steels:
ACcm -The temperature at which the solution of cementite in austenite is completed during heating.
AC1- The temperature at which austenite begins to form during heating.
ACa- The temperature at which transformation of ferrite to austenite is completed during heating.
AC4- The temperature at which austenite transforms to delta ferrite during heating.
Ae1' Aea. Aecm' Ae4 -The temperatures of phase changes at equilibrium.
Arcm- The temperature at which precipitation of cementite starts during cooling.
Ar1- The temperature at which transformation of austenite to ferrite or to ferrite plus cementite is completed during cooling.
Ara- The temperature at which austenite begins to transform to ferrite during cooling
Ar4- The temperature at which delta ferrite transforms to austenite during cooling.
Ms- The temperature at which transformation of austenite to martensite starts during cooling.
Mf- The temperature, during cooling, at which transformation of austenite to martensite is substantially completed.
NOTE: All these changes except the formation of martensite occur at lower temperatures during cooling than during heating, and depend on the rate of change of temperature.
TUMBLING- Cleaning and/or deburring articles by rotating them in a cylinder containing cleaners and/or abrasives.
TWIST- Winding departure from flatness.
ULTIMATE STRENGTH -See TENSILE STRENGTH.
VACUUM DEGASSING -Refer to DEGASSING PROCESS.
VANADIUM- (Chemical Symbol V) - Gray - white hard metal used as a strong carbide and nitride former that refines steel grain size increasing strength and toughness.
VICKERS HARDNESS (TEST) -Standard method for measuring the hardness of metals, particularly those with extremely hard surfaces; the surface is subjected to a standard pressure for a standard length of time by means of a pyramid-shaped diamond. The diagonal of the resulting indention is measured under a microscope and the Vickers Hardness value read from a conversion table.
WAVY- Not flat. A slight wave following the direction of rolling and beyond the standard limitation for flatness.
WEDGE- A steel thickness profile wherein one edge is thicker than the center, which is thicker than the other edge.
WET CHEMICAL ANALYSIS -See CLASSICAL (WET) CHEMICAL ANALYSIS
WORK HARDENING -Increase in resistance to deformation (i.e. in hardness) produced by cold working.
YIELD POINT- The load per unit of original cross section at which, in soft steel, a marked increase in deformation occurs without increase in load. A steel loaded beyond its yield point deforms plastically and will not return to its original dimension when unloaded.
ZINC- (Chemical Symbol Zn) - Blue - white metal used extensively as a coating for steel (See GALVANIZING).
ZIRCONIUM- (Chemical Symbol Zr) – Silvery metal used as a strong deoxidizer and nitride former that imparts sulfide inclusion shape control to steel resulting in improved formability.