Glossary
While molten and prior to casting, steel which has been treated with a deoxidising agent such as aluminium or silicon is called Killed Steel. The process aims to significntly lower or completely remove the steel’s oxygen content so that there is no gas formed during subsequent solidification. The resulting cast steel is non-porous and very homogeneous, and as either a flat or long product can undergo significant forming or drawing during subsequent processing.
A process typically applied in a ladle furnace for alloying, deoxidation, desulphurisation as well as for temperature adjustment prior to casting of quality steels.
Lances are hollow steel bars which can resist very high temperatures. They are used to introduce additional elements into the melting vessel after it has been charged with its principal raw materials. In both types of steelmaking, a lance is principally used to inject oxygen into the melt. This is essential in BOF steelmaking to achieve the chemical conversion of iron into steel, whereas in EAFs, oxygen injection is more usually associated with generating additional energy in the melt to reduce electricity consumption.
Lead is added to steel to enhance its machinability, and is a key feature of premium low-carbon free-cutting (free-machining) steels. Lead’s much lower melting point and the fact that it is insoluble in steel, means that during machining it melts and forms a lubricating layer at the point of contact between machining tool and the steel being turned, milled or drilled. This lubrication allows faster machining through higher rotational and material feed speeds, and enhances cutting tool life. The lead in the steel also helps reduce deformation stresses.
Along with iron ore and coke, limestone is an important ingredient in blast furnace ironmaking. The function of limestone is to react with impurities introduced by the other two ingredients to form a slag which can be removed from the furnace without contaminating the iron. The heat inside the blast furnace converts limestone into calcium oxide and CO2 gas. Calcium oxide readily reacts with impurities like silica, sulphur, alumina and magnesia to form a slag. This gradually filters down through the furnace to settle on top of the liquid iron where it can be tapped off.
Line pipe is the type of pipe that is used in the surface transmission of oil, natural gas and other fluids.
A group of commodity steel shapes that consist of rounds, squares, flats, strips, angles, and channels, which fabricators, steel service centers and manufacturers cut, bend and shape into products. Merchant products require more specialized processing than reinforcing bar.
Most pig iron is produced in blast furnaces for subsequent steelmaking at integrated steelworks, and is transferred as molten iron from BF to nearby oxygen converters. But a much smaller tonnage is produced for sale as a steelmaking or foundry raw material. This merchant pig iron is mostly made in coke or charcoal fuelled BFs and sold as ingot. Pig iron is a supplement to ferrous scrap in the EAF, and may be used instead of, or in addition to direct reduced iron or hot briquetted iron in order to make higher grades of steel that may not be achievable using only scrap.
Mild steel is a low carbon steel that is also often referred to as soft steel. It usually has a carbon content which is under 0.25%.
Mill scale forms on the surface of steel when oxygen reacts with very hot metal to form iron oxides. This occurs immediately after casting, and during reheating and hot rolling. The scale, which can range in size from a few microns to several centimetres across, has to be removed, otherwise it will damage the surface finish of the steel during any subsequent rolling. High pressure water jets are used to blast away the scale, and on a hot strip mill this occurs as the steel passes down the run-out table from the roughing mill.
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, labour relations, product markets, and management style.
An alloying element used as a raw material for some classes of stainless steel. Molybdenum in the presence of chromium enhances the corrosion resistance of stainless steel.
Nickel is a chemical element that is a silvery-white lustrous metal with a slight golden tinge. It is an important constituent of stainless steel, and increases the tensile strength of carbon steel. It is also essential to some other alloys capable of operating at very high temperatures and/or in very aggressive environments.
Nickel-based alloys are developed for very high temperature service where relatively high stresses are encountered and where high surface stability is frequently required. Typical applications are aircraft turbine and land-based turbine components.
Non-prime usually describes steel which is unsuitable for its originally intended application – either because of its metallurgy or physical condition – or is in excess of the tonnage required to fulfil a particular contract (over-rolled). Much non-prime is the result of defects created during steelmaking and downstream processing – and as a result this steel does not have the mill certification associated with prime material.
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Anonymous
Very good overview of the weekly steel market.
Anonymous