The steel & metals industry has been around for decades, and the terminology used can be very specific. In order to serve our community better and increase accessibility, we are thrilled to offer a glossary of these terms for your convenience.
Aging describes a change in a material’s mechanical properties such as an increase in hardness, yield strength, tensile strength or formability that occurs naturally at ambient or moderately elevated temperatures. Aging is a product of prior processing, chemistry or a combination of both. It can be detrimental in the case of very soft, low carbon materials, but in most cases, it is planned and engineered into the material to be beneficial.
A metallic element added during the production of a metallic material, such as steel, aluminum, copper or titanium. Alloys are created to enhance a desired property such as, but not limited to, hardness, increased corrosion resistance, or magnetic properties. An example of an alloying element is adding a minimum of 10% chromium to low carbon steel to produce stainless steel.
A “killed” steel has been deoxidized so there is no reaction between carbon and oxygen during solidification. Aluminum killed steel has been deoxidized with aluminum and silicon killed steel has been deoxidized with silicon.
A heat or thermal treatment process to increase the ductility and formability of cold worked metal. The temperature and time required to soften the material is dependent on the amount of cold work and the type of metal involved.
AOD and VOD are specialized secondary steelmaking processes used to make stainless steel and other high-grade steel alloys. They are required to remove carbon from the molten steel without removing wanted elements like chromium. The process takes several steps because several different chemical reactions must take place.
Type of steel microstructure that is non-magnetic. It is the largest category of stainless steel and offers the most resistance to corrosion in the stainless group, because of its high content of chromium and nickel.
Using computers and sensors, rolling mills can precisely control steel’s thickness while the material is being rolled at very high speeds. Using feed-forward and feed-reverse systems, the gap between the reduction rolls can be adjusted many times per second, which helps eliminate off-gauge material. This level of control is impossible with a human operator.
A special chemical composition coupled with special processing allow BH steels to have good formability prior to being painted. However, their strength and dent resistance increase during the elevated temperature of the paint curing process.
Long steel products that are hot rolled from billets or near net shapes. Merchant bar quality (MBQ), reinforcing bar (rebar), special bar quality (SBQ) are common categories of steel bars. Bars can come in various forms such as rounds, flats, angles, squares and channels.
The BOF converts the raw, molten pig-iron produced by the blast furnace to steel by using a lance to inject high pressure oxygen into the molten metal. The oxygen removes the carbon as well as other impurities from the pig-iron, in a process that is much faster and much better than historical processes.
The continuous casting of near net shape cross sections, called ‘beam blanks’ or ‘dog-bones’, has been an efficient commercial process to manufacture long steel products that will be further processed into I and H beams.
Billets are semi-finished casting items that are usually made with a continuous casting machine. They have cross-sections that are typically square and remain the same throughout the entire length. Billets are typically smaller than blooms.
A blast furnace is used by integrated steel mills to refine iron ore into molten iron, which is the main raw material for the steelmaking process. Its name comes from the “blast” of hot air and gases forced up through the iron ore, coke, and limestone that are charged the furnace. They are typically very large reaching heights up to 200 feet and achieving temperatures of over 3,000°F (1,650°C).
Blooms are semi-finished casting items that have rectangular or square cross-sections. They have cross-sections that are typically square and remain the same throughout the entire length. Blooms are typically larger than billets. They can be used as rolling material for products like pipes, rails, etc.
A sharp ridge on the edge of the metal created by manufacturing operations such as slitting, trimming, shearing or blanking. If the manufacturing process is not set up properly, it can cause a severe burr which can be a safety hazard or quality issue.
Camber is the deviation of a side edge of a steel strip from a straight edge. Camber appears as a curve along the length of the strip and is caused by one edge being longer than the other. Typically, customers will require a camber tolerance on slit material. Excessive camber is referred to as a hook or a dogleg.
Carbon steel refers to steels where the principal additions to their chemistry are carbon and manganese. Engineering the amount of carbon in the steel in conjunction with subsequent processing steps gives the steel its desired mechanical and physical properties. Carbon steel is typically separated into three designations: low, medium and high carbon. Most of the steel produced is considered carbon steel.
In the hot blast stove of a blast furnace, checker bricks are heated by the exhaust gases of the furnace, which then transfer the heat to fresh air to heat it to a specified temperature before sending it into the blast furnace. They act as a heat exchanger.
Chemistry refers to the chemical composition of the material. It is shown as a list of the elements and the amounts contained in the material. In steel, iron is by far the main component of steel, so it is not typically listed in the steel’s chemistry, but carbon (C), manganese (Mn), phosphorous (P) and sulfur (S) are typically listed at a minimum.
A steel coil is a semifinished steel product, such as sheet or strip, which has been wound or coiled after rolling. Hot and cold-roll, stainless steel, carbon and alloys, galvanized and tinplate are typically processed and shipped in coil form.
A fuel used in the steelmaking process that is created by heating coal in a low-oxygen environment. In addition to lime and iron ore, coke is one of the three main raw materials used for steel production.
Cold reduction reduces the thickness of a metal while it is at ambient temperature to achieve a desired mechanical property such as strength or hardness or dimensional property such as thickness or surface finish. Cold reduction is usually done to coiled material on rolling mills. Cold reduction is a form of cold working. Since the reduction is being done below the recrystallization temperature of the metal, there is a limit to the amount of cold reduction that can be done before the metal becomes brittle.
Causing changes to the shape and structure of a metal through production processes such as rolling, hammering, forming, stamping or stretching at ambient temperature. Since the work is being done below the recrystallization temperature of the metal, there is a limit to the amount of cold work that can be done before the metal becomes brittle.
The molds are one of the necessary parts of the continuous casting process. In this process, liquid steel is poured from the tundish into the water cooled, casting mold. Solidification of the liquid steel begins in the mold, where a thin shell of solid steel is formed that allows the rest of the steel to be further cooled as it goes further into the caster.
The degradation of a metal caused by atmosphere, moisture, or other agents. The speed of corrosion depends on the type of metal and what it is being exposed to. Corrosion of steel is commonly referred to as rust.
Scale is iron oxide that forms on the surface of steel when it is hot, and it reacts with the oxygen in the air. It must be removed prior to any subsequent forming operations. Descaling is the process of removing scale from the surface of steel and it is typically done with high pressure water sprays or shot blasting.
A high sulfur content is detrimental to steel, so it must be removed while the steel is still molten. Desulfurization occurs at various steps of the steel making process by injecting various chemical mixtures into the molten metal while it is still in the ladle. Desulfurization is done at BOF, LMF and even in the tundish prior to casting.
By using a reducing gas or elemental carbon, the oxygen atoms are removed from iron ore leaving elemental iron, without the need to go through the blast furnace process. This direct-reduced iron or DRI has less unwanted elements than steel scrap, so it is a preferred raw material to use in electric arc furnaces. DRI comes as pellets or briquettes (HBI).
Refers to the steel having two types of microstructures at the same time. It also refers to a category of stainless steel with high amounts of chromium and moderate nickel content, which creates a mixture of austenitic and ferritic microstructures within the same material. This combination offers more strength and high resistance to stress corrosion cracking, so they are suitable for high stress environments such as heat exchangers, desalination plants, and marine applications. Duplex stainless steels are also magnetic.
Rolling the edge of a strip of steel to smooth or shape the edges. Along with deburring, edge rolling can shape the edges into square or rounded edges. Edge rolled material is no longer a safety hazard because the sharp burr has been removed.
A steel-making furnace where ferrous scrap makes up most of the charge, but direct-reduced iron pellets or briquettes can also be used. Heat is supplied from electricity that arcs between large graphite electrodes to the metal bath.
ERW pipe is made by forming strips of hot-rolled steel into tubes and pipes and then welding the seam to close it. Traditionally, seamless pipes are considered better, but ERW technology has greatly improved, so they are used more and more often.
A manufacturer that purchases semi-finished materials and processes them into intermediate products. An example of a fabricator would be someone that would buy a cold roll coil and stamp it into automotive door panels and hoods to sell them to an original equipment manufacturer (OEM) like Ford or GM.
A metal product commonly used as a raw material in the steelmaking process, to aid various stages of the steelmaking process such as alloy additions, deoxidation, and desulfurization. It typically has been refined so it does not add any impurities to the steel.
FOB (Free on Board), also commonly referred to as Freight on Board in the US, is an example of a commercial term. It is important to distinguish between the US domestic usage of FOB term (defined in the Uniform Commercial Code, “UCC”) and FOB Incoterm® (defined by the International Chamber of Commerce, “ICC”) for international shipments. “FOB” can have different meanings within UCC which do not necessarily correspond with the ICC definition.
Steel that has been significantly cold reduced without being subsequently annealed. It is very stiff, and it is not intended to be used where deformation is required. Low carbon, full hard steel must have a minimum Rockwell hardness of 84 on the B scale.
A galvanized product where the coating is 95% zinc and 5% aluminum. The mixture provides extra corrosion protection and improved formability when compared to pure zinc coatings. It is applied in the hot dip process.
A galvanized product where the coating is 55% aluminum and 45% zinc. It has better corrosion resistance when compared to pure zinc coatings, because it has the electrochemical protection of zinc as well as the barrier protection of aluminum. It is applied in the hot dip process.
Steel coated with layer of zinc to provide corrosion resistance. The coating can be applied in various thicknesses using the hot dip or electrodeposition processes with several standard coating chemistries. Because of the increased corrosion resistance given by the zinc coating, galvanized steel is used in auto parts, garbage cans, storage tanks, roofing panels or fencing wire.
A galvanized product that goes through a heat treatment after being coated with pure zinc. The heat treatment causes the zinc to bond with the iron in the steel forming different layers of iron-zinc alloys. It has better adherence properties than regular galvanized material, no spangle and great paint adherence. It has somewhat eliminated the need for bonderized coatings. It is applied in the hot dip process.
Process of increasing the hardness of a metal. Hardening can be accomplished through cold working or heat treatments. It increases the material’s hardness, yield strength, tensile strength as well as its resistance to bending and stretching. However, it also decreases the material’s elongation, ductility and formability.
Hardness is the material’s resistance to indentation. Hardness is linked to the strength of the material, where the higher the hardness the higher the material’s strength and the harder it is to deform. Some examples of how hardness is measured are Rockwell Hardness or Brinell Hardness.
Additions of small amounts of microalloying elements such as columbium, vanadium, titanium, used alone or in combination, give HSLAs higher initial strength, improved formability, higher strength after forming, and even enhanced atmospheric corrosion resistance, when compared to other high carbon and alloy steels.
A coil of steel rolled on a hot-strip mill (hot-rolled steel) at high temperatures above the metal’s recrystallization temperature. Hot rolled steel is covered with mill scale and the hot roll microstructure is not ideal for forming as it is typically hard and brittle. Steel can be sold in this form, or it can be sold after further processing. Hot rolled steel is also called hot band.
A rolling mill that uses several in-line rolling mill stands to convert slabs into hot-rolled coils. After reheating the slab until it is red hot and then removing the hot mill scale with high pressure water sprays, the hot-strip mill produces a coil of flat-rolled steel from 0.250” to 0.080” in thickness.
A semi-finished type of metal, where molten metal is poured into molds, where it slowly solidifies. Once the metal is solid, the mold is stripped away, and the ingots are removed for further processing.
These facilities use a blast furnace to convert iron ore, lime and coke into molten iron and then use a BOF to convert the molten iron into molten steel. They differ from minimills in how they produce molten steel.
A steel product with extremely low carbon levels, which make it extremely soft and ductile. It is produced using the vacuum degassing process. Due to its enhanced drawability, it is used exclusively in deep-drawing applications.
A steel product with extremely low carbon levels, which make it extremely soft and ductile. It is produced using the vacuum degassing process. Due to its enhanced drawability, it is used exclusively in deep-drawing applications.
A naturally occurring mineral containing enough iron to be a commercially viable source of the element for use in the ironmaking process. Iron ore is oxidized iron and it must be mined from the earth’s crust before it is further refined into molten iron in a blast furnace. The main ores used in ironmaking are hematite, magnetite, limonite and siderite.
A secondary steel processing unit that further refines the chemistry and temperature of molten steel while it is still in the ladle. The ladle metallurgy step comes after the EAF or BOF, but prior to the to the continuous caster.
The process by which a leveling machine flattens, and/or shape corrects metal strip, coil, or sheet. There are several types of leveling processes including off-set rollers, tension leveling and stretcher leveling.
Type of steel microstructure that is formed by heat treatments. It has extremely high strength and hardness, so typical applications include blades and automotive intrusion prevention beams and bumpers. Martensitic is a small category of stainless steel that can be hardened through heat treatments and is utilized in the chemical and oil industries as well as in surgical instruments.
Properties of a material that indicate how the material will react in real world conditions. Mechanical properties can include hardness, tensile strength, yield strength, elongation, impact tests, etc. Mechanical properties are different than physical properties, which usually refer to dimensional characteristics of the material.
A term for lower quality commodity steel shapes such as rounds, squares, flats, strips, angles, and channels. It is made using appropriate controls for chemistries, mechanical properties and dimensional tolerances, but it is intended for non-critical applications.
Mill scale is the gray, flaky surface created during hot forming processes such as hot rolling or forging, where the red-hot steel contacts the oxygen in the air. Mill scale must be removed prior to any rolling or forming processes.
Mold powders are essential for the stability of the continuous casting process at all casting speeds. The main functions of mold powder are to provide lubrication and to control the heat transfer between the developing steel shell and the water-cooled copper mold.
Pipe products used by the petroleum industry. OCTG includes various pipe applications such as casing, drill pipe, and oil well tubing. OCTG materials typically have stringent specifications and requirements.
Open-pit mining is a surface mining technique of extracting rock or minerals from the earth from an open-air pit, sometimes known as a borrow. Open-pit mines are used when deposits of commercially useful ore or rocks are found near the surface.
A method of winding narrow strip steel on a much wider mandrel. By oscillate-winding the strip back and forth like fishing line on a reel or thread over a spool, a much longer strip can fit onto a coil of a specified diameter, which gives the customer longer processing runs. Oscillate winding requires welding the ends of multiple coils together to make one long coil.
Seamless pipes are manufactured by a rotary piercing process in which round billets (pipe rounds) are heated, fed between two rolls and pierced by a stationary plug. As the material flows around the plug the pipe is formed.
Crude iron as first obtained by smelting iron ore in a blast furnace. It is brittle, and not useful directly as a material except in specific instances. However, it is the primary input for steel production.
Pipe is used to transport fluids or gases and tube is used for structural applications. However, pipe and tube are often used interchangeably in steel lexicon, with a given label applied primarily as a matter of historical use.
Recrystallization is a process by which deformed microstructure grains are replaced by a new set of undeformed grains that nucleate and grow until the original grains have been entirely consumed. Recrystallization is usually accompanied by a reduction in the strength and hardness of a material and a simultaneous increase in the ductility. Recrystallization occurs at high temperatures.
A refractory material is a material that is resistant to decomposition by heat, pressure, or chemical attack, and retains strength and form at high temperatures. Refractory materials are used in furnaces, kilns, incinerators, and reactors. A common form of refractories are bricks.
The impurities in steel that can lead to it being too hard and/or brittle to meet the customer’s requirements. Residuals, also known as tramp elements, are especially problematic for soft materials where low hardness and high formability are required to form complex parts. Residuals are more prevalent in minimill material because they melt scrap that contains residuals to produce their steel.
A reversing mill has one set of rolls in one roll stand and reduces the thickness of the material by passing the material back and forth through the roll stand multiple times. The thickness gets reduced further during each pass until the required thickness is achieved.
Round, semi-finished steel length that is rolled down from a billet. Depending on the length and diameter it can be produced as coiled or cut to length for further processing. Rod is commonly drawn into wire products or used to make bolts and nails.
Rolling Mills have stands that contain rolls that are used to control the thickness of metals by compressing the material between them as they rotate. Rolling mill stands consist of several components and systems, all of which are subject to high temperatures, high loads and extreme conditions. Examples of process that would contain rolling mill stands include slabbing mills, plate mills, hot roll mills, cold roll mills, and pipe mills.
A roughing mill is a large rolling mill stand that is designed for making reductions in material thickness. The first rolling stand(s) in the hot rolling process is a roughing mill. Once reduced by the roughing stand(s), the metal continues to the finishing stands where less thickness reduction occurs, and the material is rolled to the final, desired thickness.
The layer of iron oxide that forms on the surface of steel after exposing it to the oxygen in the air while the steel is hot. Scale can take many different forms depending on the temperature and amount of exposure when it was formed.
Seamless pipes are manufactured by a rotary piercing process in which round billets (pipe rounds) are heated, fed between rolls and pierced by a stationary plug. As the material flows around the plug, the pipe is formed. Seamless pipe does not have welded seams.
Steel that does not meet requirements or specifications related to chemistry, mechanical properties, dimensional properties and/or surface quality, so it cannot be sold to the original customer. The producing mill will put this material on a secondary list and look for alternate applications - but it will be at a lower cost.
A Z-mill is a machine for reducing the thickness of metals by rolling. By using a cascading system of numerous backup rolls, it allows the application of higher roll pressures on a set of small work rolls without bending the work rolls, which would result in poor metal quality. It is a compact mill capable of making very thin thicknesses at high speeds.
A facility that buys steel, often processes it in some way then sells it in a slightly different form. A service center is different from an end-user because it sells steel, not fabricated products. Service centers use economies of scale, where they buy large quantities at a discount and then sell the material in smaller quantities at a markup.
Shaft mining is a form of underground mining where shafts are dug vertically from top to bottom to excavate ores and minerals. It is also called shaft sinking. It is best suited for concentrated minerals such as iron, coal, etc. that run in tight veins deep below the earth's surface.
Steel that is intended to be used for OCTG pipe applications. It is hot rolled material that has special requirements for chemistry, forming and welding operations. It is converted to pipe in a pipe mill.
Slabs are the output of the continuous casting process. Thick slab casters produce slabs that are 9” to 10” thick and thin slab casters produce slabs that are 2” to 3” thick. Slabs are converted to hot roll coils, sheet and plate in a hot strip mill.
Slag consists of the undesired impurities in the metal ore extracted during the smelting process. However, it also protects the liquid metal by controlling the temperature of the metal and providing a barrier against the oxygen in the air.
Cutting a sheet of steel into narrower strips. Because steel mills have limited flexibility as to the widths of the sheet that they produce, the steel will typically need to be slit to meet customer requirements.
A term for higher quality steel shapes such as rounds, squares, flats, strips, angles, and channels. It is made using more precise controls for chemistries, mechanical properties and dimensional tolerances, and is intended for more critical applications such as automotive parts and motor parts.
Steel that contains a minimum of 10% chromium is called stainless steel, because the chromium reacts with the oxygen in the air to form a microscopic, invisible layer that protects it from the environment. Higher levels of chromium and other elements such as nickel can enhance this protection even more. Stainless steel resists corrosion and staining, maintains its strength at high temperatures, and is easily maintained. It is widely used in items such as automotive and food processing products, corrosive environments such as steam heat exchangers and pipes to transport acids, and medical or health equipment. Depending on the application, stainless steel comes in many grades (chemistries), but the main stainless steel families are 300 and 400 series.
A mechanical property related to how a material reacts to outside forces. Examples of strength include how much force it takes to change the shape of a material and how it resists being stretched. Common strength measurements for metals are yield and tensile strengths.
A tandem mill is a type of rolling mill, where instead of having a single mill stand, several mill stands are set up in line with each other. As the material moves from one stand to the next, the thickness is reduced until the required thickness, properties and surface texture are achieved.
A temper mill is a metal coil, sheet, or strip processing line composed of entry and exit equipment, a one- or two-stand cold rolling mill, and automatic thickness control equipment. Typically, a temper mill is used in the last step of the cold reduction process, and it is done after annealing. Its primary purpose is to achieve the desired material thickness and improve the metal’s mechanical properties and surface appearance.
Tinning is the process of thinly coating steel coils with tin to prevent rust and environmental interaction. The resulting product of tinning is known as tinplate. Because tin is non-toxic, tinplate material is used primarily in food packaging applications such as soup cans or canned vegetables. Tinplate material is produced in tin mills and the tin can be applied using electroplating or the hot dip process.
Tolerances define the customer’s acceptable range of material parameters, which can include chemistry, mechanical properties, dimensional properties, surface quality, packaging, and more. Tolerances can come in the form of a minimum, a maximum or a range and can either be defined by the customer or an accepted industry standard. It is extremely important to fully understand all tolerances prior to accepting a customer’s order.
The act of processing material for a fee or toll. Toll processors do not own the material; they sell processing time on their equipment to the material’s owner. Examples of processing offered by toll processors can include pickling, slitting, coating, rolling, annealing, leveling, and cutting to length.
A hot strip mill reheat furnace where the slab is repeatedly lifted and set down to move it forward in the furnace. This is a newer technology that produces better quality than older push furnaces that could create surface quality issues as the slab is pushed along fixed beams.
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