STEEL TERMS GLOSSARY: C - D

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.

DUCTILITY - The property of metals that enables them to be mechanically deformed when cold, without fracture. In steel, ductility is measured by elongation and reduction of area as determined in a tensile test, or by various drawing simulations such as OLSEN, ERICHSEN, or LDH tests.