Dam
A refractory block in the blast furnace cast house which holds back the hot metal until the depth of metal in the trough is sufficient (about 300mm) to contact the bottom of a refractory skimmer block.

Dead Steel
A steel which is quite in the mould after the teeming is completed. This steel is fully deoxidized.

Deburris
Horizontal knife used to remove burrs after slitting.

Decarburisation
Loss of carbon from the surface layer of a carbon-containing alloy usually during heating, hot working or heat treatment due to reaction with one or more chemical substances in a medium that contacts the surface.

Deep Drawing
The fabrication process of flat rolled steel to make drawn parts. The part is mechanically formed through or in a die. The blank diameter is reduced; the blank contracts circumferentially as it is drawn radially inward. (See Deep Drawing Applications).

Deep Etching
Macroetching specially for steel to determine the overall character of the material that is the presence of imperfections such as seams, forgings, bursts, shrinkage-void remnants, cracks and coring.

Deep Drawing Applications
Parts/applications that require deep drawing in their fabrication. Examples are motor shells, fenders, quarter panels, door panels.

Deep Drawing Steel
A high quality low carbon steel possessing high ductility, desirable grain size, etc. which permits deep drawing.

Defect
1. Anything that renders the steel unfit for the specific use for which it was ordered. What is defective for one customer may be prime steel for another. 2. A variety of quality problems in a coil. Examples are punch marks, roll marks, oil spots, and scratches.

Deflector Roll
A roll used to change the direction of the strip.

Deformed Bar
Concrete reinforcing bars in which the surface is provided with lugs or protrusions )called deformations) which inhibit longitudinal movement of the bars relative to the surrounding concrete. The surface deformations are hot formed in the final roll pass by passing the bars between rolls having patterns cut into them so that the surfaces of the bars are forced into the depressions in the rolls to form characteristic deformations.

Defrazing (Frazing)
Removing the uneven edges at the ends of welded tube.

Degas Heat
A heat of degas steel is a heat that is produced to extremely low carbon levels through vacuum degassing.

Degassing
Liquid steel absorbs gases from the atmosphere and from the materials used in the steel making process, which cause embrittleness, voids, inclusions, and other undesirable phenomena in the steel after it solidifies. Degassing aims to remove the gases (chiefly hydrogen and oxygen).

Delay Code
A four-character code used to identify the type and reason for a delay.

Delivery End
The exit end of the line.

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

Delta Iron
Solid phase of iron that is stable from 1400 to 1539 0 C and possesses the body centred cubic lattice.

Demineralized Water
City water which is circulated through a series of three demineralizing filters to soften it and remove residuals. It is then delivered to a storage tank for use in overflowing the superheater elements and headers on the boiler during hydrostatic tests. Filling the superheaters with demineralized water prevents the raw water used in a hydrostatic test from entering the superheaters where it could cause corrosion problems

Dendrite
A crystal with a treelike branching pattern. It is most evident in cast metals slowly cooled through the solidification range.

Deoxidation
Reduction of oxygen content of the finished liquid steel by adding 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 tapping contains 400 to 800 ppm O. Deoxidation is carried out during tapping by adding into the tap-ladle appropriate amounts of ferromanganese, ferrosilicon and / or aluminum / silicon / titanium etc.

Deoxidizers
Substance having a high affinity for oxygen used for finishing steel.

Dephosphorisation
The process of reduction of phosphorus to the desired extent in steel making processes.

Depletion
Selective removal of one component of an alloy usually from the 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
The process of removing scale from the surface of hot-worked or heat-treated product by pickling, shot-blasting etc. Also, removal of scale during hot working by the application of steam under high pressure, water, coal dust, brushwood, oil, etc. Scale forms most readily when the steel is hot by union of oxygen with iron. Common methods of descaling are: (1) crack the scale by use of roughened rolls and remove by a forceful water spray, (2) throw salt or wet sand or wet burlap on the steel just previous to its passage through the rolls.

Deseaming
The removal of surface defects from ingots or semi-finished products by an oxy-gas flame.

Desiliconization
Removal of silicon from the hot metal prior to the oxygen converter process. Silicon removal is beneficial to the converter to reduce the chemical attack on the basic refractory lining and to allow the use of only minimal amounts of slag-making fluxes, thereby maximizing process yield.

Desulfurization
What Operation that injects a chemical mixture into a ladle full of hot metal to remove sulfur prior to its charging into the Basic Oxygen Furnace.
Why Sulfur enters the steel from the coke in the blast furnace smelting operation, and there is little the steel maker can do to reduce its presence. Because excess sulfur in the steel impedes its welding and forming characteristics, the mill must add this step to the steel making process.

Dezincification
Corrosion in which zinc is selectively leached from zinc-containing alloys. Most commonly found in copper-zinc alloys containing less than 85% copper after extended service in water containing dissolved oxygen.

Die
A tool having a prepared hole through which tubes are passed in the drawing or push bench process.

Die Lines
Longitudinal lines on the outer surface of a drawn tube caused by localized seizure between the tube and the die.

Die Mark
Scratch marks made during drawing due to poor condition of dies or gritty material being drawn in the die along with the wire.

Die Rolling
The process of rolling a string of blanks, each of which has varying cross-sectional area produced by heavy reductions, and specified center to center length. When sheared to length, the blanks are of identical shape. Products such as automobile axles and crank shafts are produced satisfactorily by die rolling. 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 on distance from coil, determine coating thickness by removing excess metal from the strip; the farther the die is from the steel, the heavier the coating – also called "knives" on this line.

Die Wear
The erosion of the die surfaces caused by the flow of plastic metal over them.

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

Dimensional Tolerance
A range by which a product's width and gauge can deviate from those ordered and still meet the order's requirements. (Also See Commercial Tolerance)

Dimple
The jet impact zone caused by the impingement of oxygen during lancing operation in steel-making. The oxidation reactions occur in this zone.

Dings
Kinks 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 Processes
All the methods whereby low-carbon wrought iron can be produced directly from the ore are referred to as direct processes.

Direct Reduced Iron (DRI)
What A processed iron ore that is iron-rich enough to be used as a scrap substitute in electric furnace steel making.
Why As mini-mills expand their product abilities to sheet steel, they require much higher grades of scrap to approach integrated mill quality. Enabling the mini-mills to use iron ore without the blast furnace, DRI can serve as a low residual raw material and alleviate the mini-mills' dependence on cleaner, higher-priced scrap.
How The impurities in the crushed iron ore are driven off through the use of massive amounts of natural gas. While the result is 97% pure iron (compared with blast furnace hot metal, which, because it is saturated with carbon, is only 93% iron), DRI is only economically feasible in regions where natural gas is attractively priced.

Direct Reduction Processes
The processes that produce iron by reduction of iron ore below the melting point of the iron produced.

Direct Smelting Processes
The processes that produce a molten product (similar to blast furnace hot metal) directly from ore. Direct Steel

Making Processes
The processes that produce liquid steel directly from ore.

Discard
Those portions corresponding to the top and bottom of the ingot which are removed to ensure that the remainder of the material is of satisfactory quality. Also, defective material produced in rolling or forging, to be cut off from one or both ends of the semi-finished or finished product.

Dishing
Forming a cup or depression in a forging

Divided Mould
In this method, a permanent divider is used in the center of the mould, which permits the casting of two narrow slabs simultaneously on a single strand using common containment and withdrawal units. This increases the productivity of a casting machine.

Dog Leg
Bow-legged strip, that is, a strip which has been curved in opposite directions in two adjoining portions.

Dolomite
Naturally occurring mineral consisting mainly of calcium-magnesium carbonate (Ca, Mg) CO3 used as a flux in steel plants or a refractory in basic steel making furnaces after 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). Dolomite is also used to add magnesium oxide to the sinter.

Dormant Scrap
Comprises obsolete, worn out or broken products of consuming industries. This type of scrap, because of its miscellaneous nature, requires careful sorting and classification to prevent the contamination of steel in the furnace with unwanted chemical elements from alloys that may be present in some of the scrap.

Doubles
Sheets hot-rolled after doubling.

Doubling
Folding 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 limited ductility, and highly directional mechanical properties.

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

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

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

Draft or Draught
The amount of reduction in the cross-sectional area of a tube during rolling or drawing; often in drawing, it might refer only to reduction in thickness.

Drawn
Mechanically formed by tension through or in a die.

Drawn & Ironed (D&I)
A process primarily used to manufacture two-piece beer or carbonated beverage can bodies, although some canned food product is packaged in steel D&I can bodies. An appropriately sized circular disk is drawn into a cup to approximately the finished can diameter. The side wall height is created by forcing the cup through a series of rings, ironing the metal thinner than the starting material thickness. Can bodies are coated with organic lacquers after forming.

Drawn-Over-Mandrel
A procedure for producing specialty tubing using a draw bench to pull tubing through a die and over a mandrel, giving excellent control over the inside diameter and wall thickness. Advantages of this technique are its inside and outside surface quality and gauge tolerance. Major markets include automotive applications and hydraulic cylinders.

Drifting
Expanding a forging by driving in a tapered tool.

Drop Forging
An article produced by hot working the metal between closed dies by means of a falling weight as in a drop hammer, the operation involving a modification of both the form and section 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 on a second or third die to produce a can body of the desired dimensions. Plate is coated prior to the forming process.

Draw-Thin-Redraw (DTR)
An enhancement of the DRD process for making two-piece can body utilizing high tensile TFS that has an organic polymeric coating applied prior to the forming operations. The patented DTR process is a means of subjecting the coated feedstock to forming strains such that the metal and coating avoid compacting and subsequent sidewall burnishing, thus enhancing the integrity of the organic coating. The resultant sidewall is thinned during the drawing and redrawing operations, thus facilitating the specified can body dimensions using a smaller starting blank size than that required for DRD.

Dressing
Removing surface defects or cleaning and / or reconditioning of 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 Pipe
Pipe 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 during drilling, to lubricate the drill bit and transmit the drilled core to the surface. Because of the high stress, torque and temperature associated with well drilling, drill pipe is a seamless product.

Dross
Sediment which settles in bottom of the zinc pot on the galvanize line. Also top dross, which floats on surface of pot and is skimmed off. A different type of dross also occurs on the top of the zinc pot, which is skimmed off on a regular time frame.

Dryer
Dries the strip after a rinsing process.

Dry Film Weight
Dry coating film weight is normally calculated in gm/m² or mg/in². Accurate control of dry film weight is essential to ensure that the coating material will possess its intended properties of physical and chemical resistance.

Ductile Fracture
Fracture characterized by tearing of metal accompanied by appreciable gross plastic deformation and expenditure of considerable energy.

Ductility
A qualitative, subjective property of material that indicates the extent to which it can be deformed without fracture in metal working operations such as rolling, extrusion, fabrication, etc. fracture at room temperature. It is generally expressed as total permanent strain prior to fracture, measured as elongation or reduction of area during tensile testing.

Dummy
The part of die used for rough forming the stock before the final forging operation.

Dummy Hammer
A mechanically operated hammer used for drawing out or shaping the material prior to the final forging

Dumping
Dumping occurs when imported merchandise is sold in, or for export to, the domestic market at less than the normal value of 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 exporting country) or third-country market (market used as proxy for home market in cases where home market cannot be used). The normal value of the merchandise cannot be below the cost of production.

Dumping Margin
The amount by which the normal value exceeds the export price or constructed export price of the subject merchandise.

Duplex
A category of stainless steel with high amounts of chromium and moderate nickel content. The duplex class is so named because it is a mixture of austenitic (chromium-nickel stainless class) and ferritic (plain chromium stainless category) structures. This combination was originated to offer more strength than either of those stainless steels. Duplex stainless steels provide high resistance to stress corrosion cracking (formation of cracks caused by a combination of corrosion and stress) and are suitable for heat exchangers, desalination plants, and marine applications.

Duplex Process
Steel 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 Bessemer convertor and basic open hearth furnace.