KK Group

Manufacturing Steel Since 1984

Manufacturing Steel Since 1984

Glossary


Bar

Finished product of solid section generally supplied in straight length, which are rolled from billets and may be rectangular, square, flats, channels, round, half round or polygonal. The bars may be supplied in coil form also. The dimensions generally conform to the following :

  • Rounds and Half-Rounds : Minimum diameter 5mm.
  • Squares and Polygonal : Minimum 6mm side.
  • Flat Bar (Flat) : A finished product, generally of cross section, with edges of controlled contour and thickness 3mm and over, width 400mm and below and supplied in straight lengths. The product shall have rolled edges only (square or slightly rounded). This group also includes flat bars with bulb that has swelling on one or two faces of the same edge and a width of less than 400mm.

Bloom

A semi-finished forged, rolled or continuously cast steel form whose cross-section is square or rectangular (excluding slab) and is generally more than 125 x 125mm (or equivalent cross-sectional area). This large cast steel shape is broken down in the mill to produce the familiar I-beams, H-beams and sheet piling. Reduction of a bloom to a much smaller cross-section results in formation of billets. Blooms are also part of the high quality bar manufacturing process: reduction of a bloom to a much smaller cross-section can improve the quality of the metal.

Bright Bar or Wire

Bar or wire with a bright finish obtained by cold drawing, machining, grinding etc.

Bright Ground

Bar or wire ground between abrasive wheels which give a bright finish to the material.

Bright Machined

Material which has been turned, ground, shaped or milled to size and finished with a smooth bright surface.

Butt Weld

Weld made to join two strip ends set against each other.

Butt Welding

Joining two edges or ends by placing one against the other and welding them.

Capacity

Normal ability to produce steel in a given time period. This rating should include maintenance requirements, but because such service is scheduled to match the needs of the machinery (not those of the calendar), a mill might run at more than 100% of capacity one month and then fall well below rated capacity as maintenance is performed.
Engineered Capacity The theoretical volume of a mill, given its constraints of raw material supply and normal working speed.
True Capacity Volume at full utilization, allowing for the maintenance of equipment and reflecting current material constraints. (Bottlenecks of supply and distribution can change over time--capacity will expand or reduce.)

Carbon Steel

An unalloyed steel. Steel that has properties made up mostly of the element carbon and which relies on the carbon content for structure. Most of the steel produced in the world is carbon steel. The plain carbon steels may also be classified on the basis of carbon content as hypoeutectoid (carbon content below the eutectoid value of 0.80%) or hypereutectoid (carbon content above this value)

Cast Iron (CI)

An alloy essentially of iron and carbon containing more than 2 percent carbon (usually between 2.5 and 4 percent). It also contains silicon, manganese, sulphur and phosphorus in varying amounts. The character of cast iron is controlled by the manner in which carbon is present, and the fractured surface of cast iron exhibits characteristic colour, namely white, mottle, or grey, depending on whether carbon is present wholly in combined state (as carbide) or partly in combined state or wholly in the form of graphite.

Coiled Bar

A long length of hot rolled bar produced in a continuous rolling mill and coiled in a manner similar to wire rod.

Cold Drawing

Reducing the cross-sectional area of a tube, when cold, by drawing through a die. The tubes are occasionally pushed through the die.

Cold Rolling Mill

A mill that reduces the cross sectional area of the metal by rolling at approximately room temperature.

Cut-to-Length

Process to uncoil sections of flat-rolled steel and cut them into a desired length. Product that is cut to length is normally shipped flat-stacked.

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.

Embossing

A coating defect consisting of the crawling or dewetting condition where the wet film recedes and forms a raised (in relief) impression.

Eye of Coil

The centre of the coil as wound.

Fabricator

A producer of intermediate products that does not also produce primary metal. For example, a rebar (see Reinforcing Bar) fabricator purchases rebar and processes the material to the specifications of a particular construction project.

Ferrous

Metals that consist primarily of iron.

Finish

The surface appearance of steel after final treatment.

Forge

The section of the works used to produce wrought iron blooms, slabs or bars for subsequent reheating and re-rolling.

Forging

An article produced by hot working the metal under a hammer or press. It may also refer to the process followed in producing the article.

Galvanize

A sheet product substrate to which free zinc is applied either by hot-dipping or electro-plating.

High Carbon Steel

Carbon steel containing generally more than 0.6% carbon. The more carbon that is dissolved in the iron, the less formable and the tougher the steel becomes. High-carbon steel's hardness makes it suitable for plow blades, shovels, bedsprings, cutting edges, or other high-wear applications.

ID

Inside diameter (of a coil).

Ingot

A form of semi-finished steel. Liquid steel is teemed (poured) into vertical cast iron moulds, where it slowly solidifies. Once the steel is solid, the mould is stripped, and the 25- to 30-ton ingots are then ready for subsequent rolling or forging.

Integrated Mills

These facilities make steel by processing iron ore and other raw materials in blast furnaces. Technically, only the hot end differentiates integrated mills from mini-mills. However, the differing technological approaches to molten steel imply different scale efficiencies. See Mini Mills.

Integrated Steel Producer

A steel company which manufactures solid steel products; starts with raw materials such as iron ore, flux, etc, to make molten iron; converts the molten iron to liquid steel in the steel making furnaces and processes liquid to solid steel products.

Iron Ore

Mineral containing enough iron to be a commercially viable source of the element for use in steel making. Except for fragments of meteorites found on Earth, iron is not a free element; instead, it is trapped in the earth's crust in its oxidized form. It is of two types : containing ferric oxide (Hematite) or ferro-ferric oxide (Magnetite).

Jumbo Coil

A single coil produced by welding two or more coils.

Mild Steel

Carbon steel containing generally less than 0.30% carbon.

Mini-Mills

Normally defined as steel mills that melt scrap metal to produce commodity products. Although the mini-mills are subject to the same steel processing requirements after the caster as the integrated steel companies, they differ greatly in regard to their minimum efficient size and product markets. See Integrated Mills.

Multiple Lengths

Length from which a given number of pieces of specific lengths can be cut with minimum waste.

Nickel (Ni)

An alloying element used as a raw material for certain classes of stainless steel. Nickel provides high degrees of ductility (ability to change shape without fracture) as well as resistance to corrosion. Approximately 65% of all nickel is used in the making of stainless steel.

Pig Iron

The name for the melted iron produced in a blast furnace, containing a large quantity of carbon (above 1.5%, usually between 3% to 4.5%), along with silicon, manganese, phosphorus, and sulphur in varying amounts depending upon the quality of raw materials used and solidified in moving metal moulds of a Pig Casting Machine. Pig iron is used in the foundry or for conversion into steel. Named long ago when molten iron was poured through a trench in the ground to flow into shallow earthen holes, the arrangement looked like newborn pigs suckling. The central channel became known as the "sow," and the moulds were "pigs."

Powdered Iron

The sponge iron in the purified granular form. It is used in the manufacture of many useful articles articles by the metallurgy where (1) iron powders are first compacted by pressure alone into the approximate shape of the finished article; (2) the compact is then ‘sintered’ at a temperature ranging between approximately 950 and 1095o C in furnaces provided with a protective atmosphere to prevent oxidation; and (3) the sintered articles are then pressed or machined to their final shape.

Pulverized Coal Injection System (PCI)

A blast furnace enhancement to reduce an integrated mill's reliance on coke (because of environmental problems with its production). Up to 30% of the coke charged into the blast furnace can be replaced by this talcum-like coal powder, which is injected through nozzles at the bottom of the furnace.

Red Rust

A reddish brittle coating of iron oxide which develops on an uncoated or coated steel surface when oxygen in the atmosphere mixes with iron.

Reheating Furnaces

These are divided into two general classes :

  • Batch Type : Here, the charged material remains in a fixed position on the hearth until heated to rolling temperature.
  • Continuous Type : Here, the charged material moves through the furnace and is heated to rolling temperature as it progresses through the furnace. These include pusher-type, rotary-hearth-type, walking-beam-type, walking-hearth-type and roller-hearth-type furnaces.

Reinforcing Bar (Rebar)

A commodity-grade steel used to strengthen concrete in highway and building construction.

Rod (Wire Rod)

Generally round, square, half-round, rectangular or polygonal semi-finished steel length that is rolled from a billet and coiled for further processing. Rod is commonly drawn into wire products or used to make bolts and nails. Rod trains (rolling facilities) can run as fast as 20,000 feet per minute (more than 200 miles an hour).

Rolling Mill

  1. Any of the mills in which metal undergoes a rolling process. These include the Slabbing Mill, Hot Roll Mills, Cold Roll Mills, Single Reduction Mills, and Double Reduction Mills.
  2. Any operating unit that reduces gauge by application of loads through revolving cylindrical rolls; operation can be hot or cold. The elevated temperature rolling mill is the Hot Mill and is capable of reducing the gauge of a slab 92-99%.

Roll Pass (Pass)

Openings of definite shapes formed between a set of rolls through which hot steel passes for taking up the given shape or undergoing a desired amount of reduction in sectional area. This term also applies to a single passage through a pair of rolls for the purpose of altering the shape and / or reducing the cross-sectional area.

Rolls

The rolls control the reduction and shaping of the metal. There are three parts to a roll; namely, the body, or the part on which the rolling is done, the necks which support the body and take the rolling pressure, and the wobblers, where the driving force is applied through loose-fitting spindles and boxes which together form a sort of ingenious universal coupling.

Roll Scale

Oxide of iron which forms on the surface of steel while it is being heated and rolled. Much of the scale is cracked and loosened during the rolling operation and may fall off the piece naturally or be blown off by high-pressure water sprays or other means.

Roughing Stand

The first rolling stand through which metal passes during hot rolling imparting very high reduction. Once reduced by the roughing stands, the metal continues on to the finishing stands where smoother rolls with a smaller gap are used to complete the hot roll process.

Scrap (Ferrous)

Ferrous (iron-containing) material that generally is re-melted and recast into new steel. Integrated steel mills use scrap for up to 25% of their basic oxygen furnace charge; 100% of the mini-mills' raw material for their electric furnaces generally is scrap.
Home (Revert) Scrap Waste steel that is generated from within the steel mill, through edge trimming, rejects and metallic losses in slag. It normally is sent directly back to the furnace.
Prompt (Industrial) Scrap Excess steel that is trimmed by the auto and appliance stampers and auctioned to scrap buyers as factory bundles. This is a high-quality scrap as the result of its low-residual content and consistent chemistry.
Obsolete (Reclaimed) Scrap Iron-bearing trash. Automobile hulks, worn-out refrigerators and useless storage tanks, for example, can be recovered from the junkyard and re-melted. The residual impurity of such scrap normally relegates obsolete scrap to the mini-mills (see No. 1 Heavy Melt)

Section

A hot rolled product widely used for structural purposes, with a cross-section of special contour. The common types are equal & unequal angles, bulb plate & angle, channel, round, square, flat, beam, tee bar, zed bar etc.

Shafting (Lathe Turned)

Bright material usually produced by lathe turning, polishing and hand setting to given limits of dimensions and straightness.

Sponge Iron

Iron obtained by solid state reaction. In this process, iron is not melted. For many centuries before blast furnace was developed around 1300 AD, sponge iron provided the main source of iron and steel. It was produced in relatively shallow hearths or in shaft-furnaces, both of which used charcoal as fuel. The product of these early smelting processes was a spongy mass of coalesced granules of nearly pure iron intermixed with considerable slag. Usable articles of wrought iron were produced by hammering the spongy mass, while still hot from the smelting operation, to expel most of the slag and compact the mass. By repeated heating and hammering, the iron was further freed of slag and forged into the desired shape.

Stainless Steel

The term for grades of steel that contain higher (more than 10%) chromium, with or without other alloying elements. By AISI definition, a steel is called "Stainless" when it contains 4% or more chromium. Stainless steel resists corrosion, maintains its strength at high temperatures, and is easily maintained. For these reasons, it is used widely in items such as automotive and food processing products, as well as medical and health equipment. The most common grades of stainless steel are:

  • Type 304 The most commonly specified austenitic (chromium-nickel stainless class) stainless steel, accounting for more than half of the stainless steel produced in the world. This grade withstands ordinary corrosion in architecture, is durable in typical food processing environments, and resists most chemicals. Type 304 is available in virtually all product forms and finishes.
  • Type 316 Austenitic (chromium-nickel stainless class) stainless steel containing 2%-3% molybdenum (whereas 304 has none). The inclusion of molybdenum gives 316 greater resistance to various forms of deterioration.
  • Type 409 Ferritic (plain chromium stainless category) stainless steel suitable for high temperatures. This grade has the lowest chromium content of all stainless steels and thus is the least expensive.
  • Type 410 The most widely used martensitic (plain chromium stainless class with exceptional strength) stainless steel, featuring the high level of strength conferred by the martensitics. It is a low-cost, heat-treatable grade suitable for non-severe corrosion applications.
  • Type 430 The most widely used ferritic (plain chromium stainless category) stainless steel, offering general-purpose corrosion resistance, often in decorative applications.

Steel

For the purpose of classification, steel is an iron base alloy generally suitable for working to the required shape in the solid state having a carbon content generally less than 1.5 percent and containing varying amounts of other elements. A limited number of high alloyed steels may have more than 2 percent carbon but 2 percent is the usual dividing into between steel and cast iron.

Structural

Steel product group that includes I-beams, H-beams, wide-flange beams and sheet piling. These products are used in the construction of multi-story buildings, industrial buildings, bridge trusses, vertical highway supports, and riverbank reinforcement.

Thermo-mechanical Treating (TMT)

Permanent deformation of metal with the objective usually of improvement of certain physical properties of the metal.

Ton

Unit of measure for steel scrap and iron ore.
Gross Ton 2,240 pounds (1,016.05 kg).
Long (Net) Ton 2,240 pounds (1,016.05 kg).
Short (Net) Ton 2,000 pounds (907.185 kg). Normal unit of statistical raw material input and steel output in the United States.
Metric Ton 1,000 kilograms (2,204.6 pounds or 1.102 short tons).

Tongs

Long-handled pliers used to remove scrap pieces from the welder or other sections of the line.

Wire

A finished product, round, half round, square, hexagonal, flat or of any other section including grooved section characterised by the fact that it has been subjected to a sizing operation at ambient temperature by the process of drawing through a die or by other mechanical means. Wire is generally supplied in coil form but in exceptional cases can be supplied in straight lengths.

Wrought Iron

A very low carbon iron containing varying amounts of mechanically included slag. The chief characteristic of wrought iron is that the temperatures employed in its production are so low that it gets liquified beyond pasty or semi-fused state.

 

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