Alloy steel An iron based mixture is considered to be an alloy steel when it contains more than 1.65 wt% of Manganese (Mn), 0.5 wt% of Silicon (Is), 0.6 wt% of Copper (Cu) and/or other minimum quantities of alloying elements such as Chromium (Cr), Nickel (In), Molybdenum (Mo), or Tungsten (W). Through combining different quantities and types of alloying elements, a wide variety of distinct properties can be produced in steel.
Arcing Arcing is the formation of an electric arc between the graphite electrode(s) of the furnace and the conductive content of the furnace such as steel scrap or molten steel. The arcing process that takes place in an electric arc furnace (EAF) is similar in principle to that of electric arc welding, except that the current is much higher in the EAF.
Bars Long products that are rolled from billets. The two common categories are merchant bar and reinforcement bar (rebar). Merchant bars include rounds, flats, angles, squares and channels. These products are often further processed to produce a wide variety of products such as furniture, stair railing, farm equipment, etc. Reinforcement bars are used predominantly for reinforcing concrete structure such as highways, bridges and buildings.
Billets Semi-finished steel forms that are used for the production of long products. Billets generally have square cross-sectional areas compared to blooms and slabs, which generally have larger aspect ratios. Billets can be produced from a caster or rolled from a bloom.
Blast furnace A towering cylinder lined with heat resistant (refractory) bricks, used by integrated steel works to smelt iron from iron ore. Its name is derived from the blast of hot air and gases forced up through the iron ore, coke and lime stone loaded in the furnace. Inside the blast furnace, the iron ore is chemically reduced to iron and physically converted (melted) to liquid iron. This is the iron-making process.
Carbon steel A type of steel whose properties are determined primarily by the percentage of carbon present. Minor elements are present in minute quantities below the amounts found in alloy steels.
Casting The process of pouring molten metal into a mould such that upon cooling, the solidified metal retains the shape of the mould.
Continuous casting Continuous forming of semi-finished steel products such as billets, blooms and slabs. Molten metal is poured continuously from a buffer refractory container known as a tundish into a water-cooled copper mould of the caster.
Molten steel solidifies when it contacts the water-cooled mould to form an external shell of sufficient strength that will hold the remaining molten steel in its core. A spray of water assists the extraction of heat from this partially solidified steel strand.
At the bottom of the steel caster, the steel strand is torch-cut into required lengths. Continuous casters can be used for producing slabs, blooms and billets, and are usually able to cast a few strands of steel simultaneously.
Charging The feeding of a single load of raw materials into the furnace.
Cut-and-bend It is one of the most important operations in the construction of a reinforced concrete product. It involves cutting and bending the reinforcement bar into the correct size and shape as specified in structural drawings so as to allow trouble-free placement of the steel in the structural member at the construction site.
Cutting and bending can be done on the construction site itself or at a cut-and-bend shop. The former often results in inappropriate dimensioning and inaccurate bending. The latter provides a controlled and organised environment where skilled operators produce consistently good quality products.
With prefabricated cut-and-bend rebars, construction sites reduce material wastage and fixing time significantly.
Electric arc furnace A steelmaking furnace which predominantly uses scrap as an iron source. The furnace houses either one or three graphite electrodes from which an electric arc can be generated to provide heat to melt the steel scrap.
Electricity can be applied either as direct current (DC), where only one electrode is required, or alternate current (AC), where three electrodes are required. These two types of furnaces are respectively known as DC furnace and AC furnace.
Flat products Steel products with typical aspect ratios of greater than 100. Examples are sheets, strips and plates used in automotives, shipbuilding and electronic white goods.
Ladle A refractory brick-lined steel vessel that is usually shaped like a bucket. It is used for transferring molten steel between processes in a steel plant. For instance, a ladle can be used to transfer molten steel from the electric arc furnace to the ladle furnace for secondary refinement and then to transfer the refined molten steel to the continuous caster.
Long products Refers to steel products such as bars, rods and structural constructions that are "long" rather than "flat". These are used for building projects.
Mesh Another name for Welded Wire Mesh
MT Metric tonne — 1 tonne is equivalent to 1,000 kg
Precast concrete (PC) A technology which involves casting building units (e.g. toilets, rooms, balconies, etc) away from the installation site, so that casting and on-site work can take place simultaneously and reduce project time
PC wires Wires (mild or high tensile steel round bars with diameters ranging from 5mm to 40mm) that are used in precast concrete
Pig iron Refers to melted iron (containing carbon above 1.5%) produced in a blast furnace. Molten iron is poured through a trench before flowing into shallow earthen moulds arranged along the side of the trench. As this resembles newborn pigs suckling at their mother’s side, the trench became known as the “sow” and the moulds as “pigs”.
Radiation Spontaneous disintegration of radioactive elements (e.g. Co-60, Ra-226, Cs-137) into other elements, accompanied by the radiation of high energy and harmful y-rays.
If a radioactive material is melted in the electric arc furnance, Co-60 is the most likely radioactive element to be alloyed with the steel due to its close melting point, while Cs-137 ends up in the dust and Ra-226 in the slag.
Rebars Another name for reinforcement bars
Reinforcement bars Steel rods used to reinforce or strengthen thick concrete structures.
Rods Another name for wire rods
Refractories Heat resistant material used for lining the furnace and ladle to provide heat insulation and protect the equipment that is usually made of steel. Refractory material is available in either brick form or paste form.
Rolling The reduction in diameter of semi-finished steel products such as billets, blooms and slabs by squeezing the products between horizontal or vertical pairs of rollers.
The distinction between cold- and hot-rolling is the temperature at which rolling is carried out. Cold-rolling often takes place at room temperature while the hot rolling temperature range varies from metal to metal. The two processes impart different properties to the products.
Slag A by-product of the iron and steelmaking process comprising largely of limestone. During steelmaking, slag, which has a lower density than molten steel, floats above the molten steel and acts as a scavenger for undesirable elements in the steel.
Once cooled and solidified, slag can be used in soil mixtures, road stones and cement.
Steel scrap Scrap is the collective name for ferrous components that have reached the end of their useful life cycle, for instance, unserviceable machine parts, steel parts of ships, bridge structures, old car parts as well as reverted ferrous materials from steelmaking.
Strands Cables produced by taking relevant diameters of wires braided together in a bundle, and can be used in precast concrete or wall anchors, lifting strands, etc.
Tensile strength The greatest longitudinal stress a material can bear without tearing apart
Tapping The running off of molten steel from the tap hole in a furnace or vessel
Tundish A shallow, refractory-lined basin that is placed under a ladle and above a continuous caster. A tundish acts as a buffer by receiving the liquid steel from the ladle prior to entering the cast, allowing the operator to regulate the flow of metal into the mould.
Welded wire mesh Fabric reinforcement that is made up mainly of high-strength wires that are welded at intersections. The use of mesh as reinforcement significantly reduces cutting and fixing time at construction sites. It also enables the simplification of the engineering design and drawing.