learning center glossary

8/9/2019 Learning Center Glossary

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Learning Center GlossaryAbout us

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A four-character code used to identify the type and reason for

a delay.

Delivery EndThe exit end of the line.

Delivery Tail EndThe outside lap of the produced coil on the delivery reel.

Delta IronSolid phase of iron that is stable from 1400 to 1539 0 C andpossesses the body centred cubic lattice.

Demineralized WaterCity water which is circulated through a series of threedemineralizing filters to soften it and remove residuals. Itis then delivered to a storage tank for use in overflowing the

superheater elements and headers on the boiler duringhydrostatic tests. Filling the superheaters with demineralized

water prevents the raw water used in a hydrostatic test fromentering the superheaters where it could cause corrosionproblems

DendriteA crystal with a treelike branching pattern. It is mostevident in cast metals slowly cooled through thesolidification range.

Deoxidation

Reduction of oxygen content of the finished liquid steel byadding deoxydizers in the bath, in ladles or in the moulds.Deoxidation is the last stage of steel making. In all types of

steel making processes, the steel bath at the time of tappingcontains 400 to 800 ppm O. Deoxidation is carried out duringtapping by adding into the tap-ladle appropriate amounts offerromanganese, ferrosilicon and / or aluminum / silicon /titanium etc.

DeoxidizersSubstance having a high affinity for oxygen used for finishing

steel.

DephosphorisationThe process of reduction of phosphorus to the desired extentin steel making processes.

DepletionSelective removal of one component of an alloy usually fromthe surface or preferentially from grain boundary regions.

Deseaming (Scarfing)The removal of surface defects from ingots or semi-finished

products by an oxy-gas flame.

Descaling


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specified center to center length. When sheared to length, the

blanks are of identical shape. Products such as automobileaxles and crank shafts are produced satisfactorily by dierolling. The blanks are rolled with or without finishing,depending upon the particular product section.

Dies (Galvanize)Air pressure devices in the Sheet Mill which, depending ondistance from coil, determine coating thickness by removingexcess metal from the strip; the farther the die is from thesteel, the heavier the coating also called "knives" on thisline.

Die WearThe erosion of the die surfaces caused by the flow of plasticmetal over them.

Differential Coatings

Coatings on flat rolled products whereby the thickness of thecoating on the one side is heavier than the other side.

Dimensional ToleranceA range by which a product's width and gauge can deviate fromthose ordered and still meet the order's requirements. (AlsoSee Commercial Tolerance)

DimpleThe jet impact zone caused by the impingement of oxygen during

lancing operation in steel-making. The oxidation reactionsoccur in this zone.

DingsKinks on sheet surface.

Direct Casting (Top Pouring)Direct pouring of ingots or castings from ladle, that is,without using any refractory reservoir or tundish, in between.

Direct ProcessesAll the methods whereby low-carbon wrought iron can beproduced directly from the ore are referred to as directprocesses.

Direct Reduced Iron (DRI)What A processed iron ore that is iron-rich enough to be usedas a scrap substitute in electric furnace steel making.Why As mini-mills expand their product abilities to sheetsteel, they require much higher grades of scrap to approachintegrated mill quality. Enabling the mini-mills to use ironore without the blast furnace, DRI can serve as a low residual

raw material and alleviate the mini-mills' dependence oncleaner, higher-priced scrap.How The impurities in the crushed iron ore are driven offthrough the use of massive amounts of natural gas. While the

result is 97% pure iron (compared with blast furnace hotmetal, which, because it is saturated with carbon, is only 93%


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iron), DRI is only economically feasible in regions wherenatural gas is attractively priced.

Direct Reduction ProcessesThe processes that produce iron by reduction of iron ore below

the melting point of the iron produced.

Direct Smelting ProcessesThe processes that produce a molten product (similar to blastfurnace hot metal) directly from ore. Direct Steel

Making ProcessesThe processes that produce liquid steel directly from ore.

DiscardThose portions corresponding to the top and bottom of theingot which are removed to ensure that the remainder of thematerial is of satisfactory quality. Also, defective material

produced in rolling or forging, to be cut off from one or bothends of the semi-finished or finished product.

DishingForming a cup or depression in a forging

Divided MouldIn this method, a permanent divider is used in the center ofthe mould, which permits the casting of two narrow slabssimultaneously on a single strand using common containment and

withdrawal units. This increases the productivity of a casting

machine.

Dog LegBow-legged strip, that is, a strip which has been curved inopposite directions in two adjoining portions.

DolomiteNaturally occurring mineral consisting mainly ofcalcium-magnesium carbonate (Ca, Mg) CO3 used as a flux insteel plants or a refractory in basic steel making furnacesafter calcination (high temperature firing or dead burning).High purity dolomite is greater than 97% CaO + MgO and 0.5-3%impurities (mostly silica, iron oxide and alumina). Dolomiteis also used to add magnesium oxide to the sinter.

Dormant ScrapComprises obsolete, worn out or broken products of consumingindustries. This type of scrap, because of its miscellaneousnature, requires careful sorting and classification to prevent

the contamination of steel in the furnace with unwantedchemical elements from alloys that may be present in some ofthe scrap.

DoublesSheets hot-rolled after doubling.


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DoublingFolding a sheet or sheet-pack on itself, about the middle,before rolling further.

Double (Cold) Reduced (DR)1. Material that has been cold reduced in thickness twice. 2.Plate given a second major cold reduction following annealing.

Double reduced products are relatively hard, have limitedductility, and highly directional mechanical properties.

Double Skin (Curtaining)A secondary layer of steel on ingot surface, arising fromoverflow of molten metal from interior to the space betweenthe solidified ingot face and mould wall. It is also formed by

splashings.

Dozzle

A hollow refractory brick preheated to high temperature andused to provide a feeder head for small ingots.

DQ"Draw quality" = more flexible grade of steel.Flat-rolled products produced from either deep drawing rimmedsteel or extra deep drawing aluminum killed steels. Specialrolling and processing operations aid in producing a product,which can stand extreme pressing, drawing or forming, etc.,without creating defects.

Draft or DraughtThe amount of reduction in the cross-sectional area of a tube

during rolling or drawing; often in drawing, it might referonly to reduction in thickness.

DrawnMechanically formed by tension through or in a die.

Drawn & Ironed (D&I)A process primarily used to manufacture two-piece beer orcarbonated beverage can bodies, although some canned foodproduct is packaged in steel D&I can bodies. An appropriatelysized circular disk is drawn into a cup to approximately thefinished can diameter. The side wall height is created byforcing the cup through a series of rings, ironing the metalthinner than the starting material thickness. Can bodies arecoated with organic lacquers after forming.

Drawn-Over-MandrelA procedure for producing specialty tubing using a draw benchto pull tubing through a die and over a mandrel, givingexcellent control over the inside diameter and wall thickness.

Advantages of this technique are its inside and outsidesurface quality and gauge tolerance. Major markets includeautomotive applications and hydraulic cylinders.

DriftingExpanding a forging by driving in a tapered tool.


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Drop ForgingAn article produced by hot working the metal between closeddies by means of a falling weight as in a drop hammer, theoperation involving a modification of both the form andsection of the stock from which the forging is produced.

Draw-Redraw (DRD)

Process for making two-piece cans in which a circular blank is

drawn into a die to form a shallow cup and then is redrawn ona second or third die to produce a can body of the desireddimensions. Plate is coated prior to the forming process.

Draw-Thin-Redraw (DTR)An enhancement of the DRD process for making two-piece canbody utilizing high tensile TFS that has an organic polymericcoating applied prior to the forming operations. The patentedDTR process is a means of subjecting the coated feedstock toforming strains such that the metal and coating avoid

compacting and subsequent sidewall burnishing, thus enhancingthe integrity of the organic coating. The resultant sidewallis thinned during the drawing and redrawing operations, thusfacilitating the specified can body dimensions using a smaller

starting blank size than that required for DRD.

DressingRemoving surface defects or cleaning and / or reconditioningof castings, ingot, bloom or slab by chipping, deseaming,scarfing, grinding or other methods.

Dressing of Coil

Eliminating any damage or defects from outer or inner diameter

of coil in preparation for shipping.

Drill PipePipe used in the drilling of an oil or gas well. Drill pipe is

the conduit between the wellhead motor and the drill bit.Drilling mud is pumped down the center of the pipe duringdrilling, to lubricate the drill bit and transmit the drilledcore to the surface. Because of the high stress, torque andtemperature associated with well drilling, drill pipe is aseamless product.

DrossSediment which settles in bottom of the zinc pot on thegalvanize line. Also top dross, which floats on surface of pot

and is skimmed off. A different type of dross also occurs onthe top of the zinc pot, which is skimmed off on a regulartime frame.

DryerDries the strip after a rinsing process.

Dry Film WeightDry coating film weight is normally calculated in gm/m ormg/in. Accurate control of dry film weight is essential to


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ensure that the coating material will possess its intendedproperties of physical and chemical resistance.

Ductile FractureFracture characterized by tearing of metal accompanied byappreciable gross plastic deformation and expenditure ofconsiderable energy.

DuctilityA qualitative, subjective property of material that indicatesthe extent to which it can be deformed without fracture inmetal working operations such as rolling, extrusion,fabrication, etc. fracture at room temperature. It isgenerally expressed as total permanent strain prior tofracture, measured as elongation or reduction of area duringtensile testing.

DummyThe part of die used for rough forming the stock before the

final forging operation.Dummy HammerA mechanically operated hammer used for drawing out or shaping

the material prior to the final forging

DumpingDumping occurs when imported merchandise is sold in, or forexport to, the domestic market at less than the normal valueof the merchandise, i.e., a price which is less than the price

at which identical or similar merchandise is sold in the

comparison market, the home market (market of exportingcountry) or third-country market (market used as proxy forhome market in cases where home market cannot be used). Thenormal value of the merchandise cannot be below the cost ofproduction.

Dumping MarginThe amount by which the normal value exceeds the export priceor constructed export price of the subject merchandise.

DuplexA category of stainless steel with high amounts of chromiumand moderate nickel content. The duplex class is so namedbecause it is a mixture of austenitic (chromium-nickelstainless class) and ferritic (plain chromium stainlesscategory) structures. This combination was originated to offer

more strength than either of those stainless steels. Duplexstainless steels provide high resistance to stress corrosioncracking (formation of cracks caused by a combination ofcorrosion and stress) and are suitable for heat exchangers,desalination plants, and marine applications.

Duplex ProcessSteel making by a combination of two processes, such as

Bessemer and open hearth processes or open hearth and electric

processes, the popular combination being one using acid

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