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Glossary

So you don’t know what a slab is? No problem. Here you’ll find explanations of the specialized terms and abbreviations from the world of thyssenkrupp Steel Europe.

A

Finishing area

Equipment and operations used to provide steel products with the desired appearance after forming (straightening, cutting, etc.).

AOD converter

Special converter for steels resistant to corrosion, acid and heat in which the carbon content is reduced by injecting argon and oxygen. AOD: Abbreviation for argon oxygen decarburization.

B

Hot-rolled sheet

Sheet cut from hot-rolled wide strip, primarily in thicknesses of up to 15 mm (max. 20 mm).

Strip casting

With the technology applied at thyssenkrupp, liquid steel is cast between two rotating rolls and then solidifies into a hot strip. Because conventional hot rolling is not required, this saves one entire process step.

Slab

Compact ingot made from crude steel. Product of the casting process in a steel mill; used as input stock for the rolling mill to produce hot strips or quarto plates.

C

Coil

Steel strip wound into a coil.

D

Downstream activities

Further steps for processing flat steel to add greater value, e.g. surface finishing, steel service or joining technology.

E

Electrical steel

Steel produced by melting in an electric arc furnace or induction furnace. The operation method of electric steel furnaces allows the production of chemically resistant types of steel, tool and high-speed steels, specialty steels for mechanical engineering, aerospace and nuclear technology, and magnetic materials.

F

Sheet

Flat product in thicknesses from 0.35 to less than 3.00 mm: cold-rolled flat products made of soft or higher-strength grades for cold forming. Primarily metallic or organic coatings.

G

Casting-rolling line

Modern production line based on thin slab technology for manufacturing hot strips from molten crude steel in just one production step.

Heavy plate

Hot-rolled sheets with a minimum thickness of 3 mm. Heavy plates are supplied in all alloyed and unalloyed steel grades.

H

Blast furnace sand

Blast furnace slag (granulated) quenched with water and vitreously solidified. Raw material for cement manufacturing.

Blast furnace

Equipment for smelting processed iron ore into hot metal. It operates based on the counter-current principle. In other words, the charge (consisting of ore, burden, additives and coke) is supplied from the top – usually from a rotating chute. Wind, preheated in the gas-heated, hot-blast stoves and injected via the bottom tuyeres arranged in a ring over the furnace cross section, flows toward the charge from the opposite direction. Coke serves as a reducing agent. Depending on the charge and the type of operation, various types of pig iron or ferro-alloys can be produced. A furnace remains in operation for many years (furnace campaign). The capacity and cost-efficiency of a blast furnace can be increased by larger furnace units, automatic charge supply, burden preparation, high hot-wind temperatures, oxygen-enriched wind or counter-pressure at the charging door. By-products of the blast furnace are blast furnace gas and blast furnace slag.

Blast furnace gas

A quarter of the blast furnace gas consists of carbon monoxide (CO); it is utilized completely in modern steel mills.

I

Interior high pressure remolding

Innovative forming process in which a pressurized liquid is used as an active medium in a closed die. It can be used to manufacture highly complex shapes such as tubular output sections.

K

Cold strip

Made by cold reduction, this flat product is available in widths of up to 2,000 mm and thicknesses from 0.35 to approx. 4 mm for quality steel. The advantages of cold-rolled strips in comparison with hot-rolled strips include better surface quality, lower tolerances and thinner dimensions.

Cold rolling

A forming process that takes place following hot rolling or strip casting. In the rolling gap of the cold rolling mill, high pressure is applied to the rolling stock between two rollers to reduce it to a specified thickness. Tandem cold rolling lines for quality steel consist of up to five rolling stands set up in a closely spaced row. It differs from hot rolling based on the temperature. In cold rolling, the rolling temperature is always below the recrystallization temperature, which means that subsequent annealing is always required.

L

Alloy

Steel materials with additional metallic or non-metallic elements (e.g. carbon, chrome, silicon).

M

Burden

A charge supplied to the blast furnace that consists of (1) input materials that contain iron oxide and (2) additives.

Multi-processing line

A system in which several process steps take place in one pass; in conventional manufacturing, these steps must be performed one after the other in different units.

N

Sustainability

Economic, social and ecological goals are considered equally and seen from their networked perspective.

O

Surface finishing

Corrosion protection for high-quality flat steel consisting of metallic (zinc, nickel, aluminum) or organic coatings (paint, plastic).

Oxygen-steel converter

Refractory-lined vessel for refining (converting) pig iron into steel. Top-blowing oxygen onto the molten material decreases the carbon content to percentages up to 0.1%.

P

Primer

Bonding agent used between steel and a coating material that adheres poorly or not at all when applied directly to steel. Primers are excellent protective coatings against corrosion and base coats for adding layers of paint later.

PVD/CVD

Abbreviation for physical or chemical vapor deposition.
Surface finishing with metallic, organic or inorganic layers created from precipitation in the vapor phase.

Q

Quality steels

Term from DIN EN 10020 – “Definition and classification of grades of steel.” Plain-carbon steels (base steels, unalloyed quality, unalloyed stainless steels) are differentiated from alloyed steels (alloyed quality and alloyed stainless steels).

Quarto reversing mill

Plant for manufacturing heavy plate with a four-high stand (four rolls).

Cut-to-length line

Used to manufacture sheet steels from wide strip and to cut slit strips to length (slit strip in bars). Straighteners and rolling stands are included along the line. The cut-to-length line is usually positioned parallel to the slitting line.

R

ReflectionsOne®

A wide range of colors for building with steel developed by color designer Friedrich Ernst v. Garnier. In the meantime, these colors have already been used successfully for many major buildings all over the world.

Reversing stand

Reversing stand: A rolling stand that forms rolling stock by passing it back and forth between the adjustable rolls. The equipment consists of one or two rolling stands, where at least one carries out several passes in reverse.

Pig iron

According to DIN EN 10001, pig iron is an alloy of iron and more than 2% carbon (C). It may also contain other elements up to a specified amount. (Mn < 30%, Si < 8%, P < 3%, Cr < 10%, others < 10%). Molten pig iron is processed into steel or cast iron. Steelmaking pig iron is classified into types based on low or high phosphorous content.

Crude steel

Available in liquid or solid form. In either case, it is a crude product. In the liquid state, it is used for the casting of ingots, strands or steel.

S

Shaft furnace

Unit for melting pig iron from ferrous materials already in the steelworks stream that have not yet been able to be used.

Slag

During every melting process, a mass of oxides forms, and due to its low specific weight it floats on the hot metal or molten steel. The undesirable by-elements separated from the iron oxide are transferred to the slag. In the solidified state, the structure of the slag is vitreous or stony. Slag from the steelworks is a usable material: blast furnace slag is processed into slag cement (Iron Portland and blast furnace cement), granulated-slag brick, foamed slag, slag lime, road-building materials, track ballast and slag wool. Finely ground converter slag that contains phosphor is a valuable fertilizer.

Hot-dip coating

The sheet or strip is coated by dipping it into a bath of molten metal (e.g. zinc, tin, aluminum, lead or their alloys). Dimensional standard DIN EN 10143.

Secondary metallurgy

Also called ladle metallurgy, this is the generic term for all processes used for deoxidation, degassing, alloying, inclusion shape control and improving the degree of steel purity. The majority of these take place in a vacuum.

Simultaneous and concurrent engineering

Close technical cooperation with the automotive industry with regard to material and production-integrated vehicle body development.

Sinter

In the sintering plant, ore dusts and concentrates are agglomerated into larger pieces. To do so, the fine-grained material, which contains iron oxide, is heated until the surface melts and then “bakes” together.

Sintering plant

Fine-grained iron ore is sintered together here with additional materials, coke, additives, etc. “Sintering” is a continuous process for agglomerating ore dust on a sintering belt. This is required because in its original state, the fine-grained ore cannot be used in the blast furnace. It would negatively affect the circulation of gas in the blast furnace.

Special structural steels

Materials of particular, documented quality that exceeds the requirements of the standards due to the development work done by the manufacturers.

Slit strip

Wide hot-rolled or cold-rolled strip (rolling width > 600), split by slitting on the slitting line to final strip widths < 600 mm. Delivered in rolls (coils), but also cut to length to strip in bars. The slitting is also used for coated wide strips.

Steel service center

Steel service centers are advanced, highly efficient processing facilities with a comprehensive delivery and service program of slit strips, sheets and blanks in hot-rolled and cold-rolled versions, with surface coating and in stainless steel. They function as a link between roll manufacturers and steel processors.

Stainless

English term for rust-proof steel.

Quenching unit

Device in which the sheets to be hardened are held in place with hydraulically positioned “feet” during the quenching process with pressurized water. (Alternative design: Roll quenching unit. During quenching, the sheet continues to move between guide rollers.)

Pusher furnace

Furnace for heating up continuous casting segments (slabs) to rolling temperature. The slabs are pushed through the furnace. Alternative design: Walking beam type furnace – here, the slabs are transported through the furnace by lifting them with the walking beams and setting them down further toward the front.

Continuous casting

Semi-continuous process for manufacturing slabs from molten steel. In the process, the steel is cast via a distributor into a cooled mold that determines the dimensions (width, thickness) of the slab. Just as the skin is solidifying, the casting strand emerges from the mold, and during further cooling it is guided between rolls, redirected horizontally and cut to the required slab length with a cutting torch.

Supply chain management

Supply chain management takes the entire supply chain of a company into consideration with the goal of optimizing the flow of information and material between its internal and external suppliers, its manufacturing area, its distributors and its customers.

T

Tailored blank

Semi-finished parts made from individual sheets with identical or different steel grades, thicknesses or surface finishes, the parts of which are welded together, e.g. laser welding. Tailored blanks can be formed and are customized with regard to special customer requirements.

Tandem mill

A mill in which the rolling stands are arranged in a single row (tandem arrangement). In general, tandem cold strip lines consist of two to five duo, quarto, or sexto stands positioned close together and through which the rolling stock passes once or several times.

Torpedo ladles

Special track-bound transportation containers for hot pig metal. They have a capacity of up to 300 tons of hot metal at a temperature of approx. 1,500°C.

Tear-type plates

Hot-rolled sheets with tear pattern, used as checker and tear plates.

U

ULSAB

Ultralight steel auto body. The ULSAB-AVC (Advanced Vehicle Concepts) program is an important element of the continuous efforts of the international steel industry to ensure the future of steel as the material of first choice for automotive manufacturers.

V

Vacuum facility

Unit for subsequent treatment of steel under significantly reduced pressure suitable to achieve especially high purity, low gas content and tight alloy tolerances. This allows high quality requirements to be met.

Heat treatment (quenching and tempering)

Type of heat treatment with hardening (quenching at a high temperature) and tempering (annealing at a lower temperature).

Wear-resistant steels

Group of steels with high wear resistance when subject to friction or impact due to their microstructure and/or hardness. thyssenkrupp trademark: XAR®.

W

Heat treatment of heavy plates

Annealing of heavy plates in furnaces to adjust certain microstructures and, as a result, properties that cannot be achieved directly in the rolling process.

Standard processes:

  • Water or oil hardening and possible tempering
  • Normalizing and possible tempering

Hot (wide) strip

Hot-rolled product with a rectangular cross-section width of at least 600 mm wound into coils immediately after rolling, edges positioned as close to exactly on top of each other as possible (like a mainspring). Manufactured on hot (wide) strip mills, primarily in a continuous process, in thicknesses of 1.5 to 25.0 mm and widths of up to 2,000 mm. Hot (wide) strip is used as input stock for sheet steel and heavy plates as well as cold (wide) strip.

Hot strip mill

Production lines for manufacturing hot-rolled strip. Completely continuous mills consisting of one or several roughing stands as well as a finishing mill with seven finishing stands.

Hot rolling

Forming process. Rolling at high temperatures enables a large reduction in thickness, e.g. a slab can be formed into thin hot-rolled strip.

Tinplate

Tin-coated, cold-rolled black plate in rated thicknesses of 0.17 to 0.49 mm, double-reduced tinplate from 0.14 to 0.29 mm made of soft, unalloyed steel in accordance with DIN EN 10203. The tin is applied electrolytically on one or both sides in identical or different coating thicknesses. Tin layer increments from 1.0 to 10 g/m² per side. An additional coat of paint may improve corrosion resistance. Mostly used in the packaging industry (with a high recycling rate!), but also for household goods and toys. Technical delivery conditions in DIN 10205.

Magnetically soft steels

These steels are characterized by a slight magnetic susceptibility, high permeability and low remagnetization loss. The microstructure should have as few lattice defects and internal stresses as possible in order to make Bloch wall motion easier. Unalloyed or low-alloyed types are used in heavy current engineering. Dynamo and transformer sheet materials are alloyed with Si in order to keep eddy current losses low.

Z

Toughness

The work stored by deformation or another type of energy conversion up to the breakage point.

Tensile strength

Maximum of the stress-elongation curve determined during tensile testing. Calculated from the quotient of the maximum tensile force and the output cross-section of the sample. Unit: MPa.

Scales

Oxide layer that forms on the surface finish during batch annealing, rolling or forging of steel. A scale coat consists of several oxidation layers with differing chemical compositions (rolling skin).

Finishing area

Equipment and operations used to provide steel products with the desired appearance after forming (straightening, cutting, etc.).

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