Steel terminology
A
ADDITIONS:
Materials, typically alloy elements, added to molten steel to produce the chemical specifications for the desired steel grade.
ALLOY:
A substance that has metallic properties and is comprised of two or more chemical elements of which at least one is a metal.
ALLOY STEEL:
Steel containing one or more alloying element. Steel is classified as alloy when the maximum content of alloying elements exceeds one or more of the following: manganese 1.65%, silicon 0.60%, copper 0.60%.
ALLOYING ELEMENTS:
Chemical elements added for improving the properties of the finished products. Some alloying elements are nickel, chromium, manganese, molybdenum, and silicon.
ANNEALING:
A process involving heating and cooling, usually applied to induce softening of steel. The term also refers to treatments intended to alter mechanical or physical properties, produce a definite microstructure or remove gasses.
ARGON SHROUD:
A procedure using argon gas to shield molten steel from oxygen as it is teemed from the ladle.
ARGON STIRRING:
An inert gas introduced through a nozzle to stir molten steel to promote chemical and temperature homogenization and float out inclusions.
AUSTENITE:
High-temperature solid form of steel with face-centered cubic crystal structure.
B
BILLET:
A semi-finished piece of steel that results from rolling an ingot or a bloom. It may be square but is never more than twice as wide as thick. Its cross-sectional area is usually not more than 36 square inches.
BLOOM:
A semi finished piece of steel resulting from the rolling or forging of an ingot. A bloom is square or not more than twice as wide as thick and usually not less than 36 square inches in cross-sectional area.
BLOOM SHEAR:
A shear used to cut a rolled ingot into shorter bloom lengths or to cut off the ends of a bloom.
BLOWHOLE:
An internal cavity in steel produced by gases during the solidification of the metal.
BOTTOM POURING:
The process of pouring ingots using a refractory runner system to fill them from the bottom of the ingot molds.
BREAKOUT:
Liquid steel flowing through the shell of a ladle or EAF.
BRINNEL HARDNESS:
A hardness test commonly used for soft steel and metals which measures diameter of an indentation made by a steel ball under a given load.
BUTT:
An unfinished or incomplete ingot.
C
CARBIDE:
A compound of iron (or other element) and carbon in steel, forming a very hard, nonmetallic substance (Fe3C). Fe3C is also called cementite.
CASTING:
Pouring molten metal into a mold, or the metal object (i.e., ingot) produced by such pouring.
CASTING POWDER:
A powder applied to the inside of a mold before teeming to prevent the metal from sticking to the mold.
CHARGE:
To load a furnace with scrap and flux prior to melting, or to load a soaking pit with ingots for reheating.
CHEMISTRY:
The chemical constituents of a heat of steel.
COLD WORKING:
Rolling or drawing semi-finished steel products to provide higher physical properties or better surfaces than can be produced by hot-working.
CONTINUOUS CASTER:
A machine used to continuously produce blooms from molten steel with no interruptions or intermediate operations.
CREEP:
Failure of a metal caused by gradual elongation due to constant stress.
CRYSTAL:
Physically uniform solids composed of atoms bonded together in a definite geometrical pattern or structure.
CRITICAL TEMPERATURE:
The temperature at which a steel transforms one crystal structure into another because of atom rearrangement.
D
DECARBURIZATION:
Loss of carbon at the steel surface caused by poor atmosphere control.
DEGASSING:
Lowering the hydrogen and oxygen content of the steel by placing the molten steel in a vacuum.
DENDRITES:
Crystals that form in a tree-like pattern during solidification.
DEOXIDIZE:
Removal of oxygen from steel.
DIFFUSION:
Movement of atoms in solids. Heat provides the energy for atom movement.
DRAW:
To empty a soaking pit one ingot at a time to feed rolling operations (FSP), or to pull steel (usually cold) through a die to change its dimensions and mechanical properties.
DUCTILITY:
Ability to undergo permanent changes of shape without rupturing.
E
ELASTIC DEFORMATION:
Temporary distortion of a material under the action of applied stresses.
ELECTRIC ARC FURNACE (EAF):
A refractory-lined steel vessel used to melt steel. An electric arc generates the heat.
ELECTRODE:
A carbon (graphite) rod that carries electricity to melt the scrap in an EAF.
ENDOTHERMIC:
A chemical change in which there is absorption of heat.
ETCH:
A steel sample treated with acid to reveal its microstructure; used to visually check conditions such as porosity, large inclusions, or other nonconformities.
EXOTHERMIC:
A chemical change in which there is liberation of heat.
F
FATIGUE:
Failure of metal due to repeated cyclic stressing.
FETTLE:
To prepare a furnace for charging and melting by repairing eroded areas of the refractory.
FLASH STICKER:
An ingot that will not separate from the mold because of leakage that
occurred between the mold and the mold stool.
FLUX:
A slag-making ingredient or the increased fluidity of slag.
FORGING:
Forming hot metal in the desired shape by means of hammering or pressing.
FREEZE:
Solidify molten steel as it cools from the liquid to solid state.
G
GRADE:
Classification of steel based on carbon content or mechanical properties.
GRAIN:
Orderly arrangement of atoms or crystal structure. Individual crystal of a microstructure.
GRINDING:
Method of conditioning steel by removing surface flaws using a power-driven grinding wheel.
H
HARDENABILITY:
The depth and distribution of hardness below the surface of steel.
HARDENING:
The process of increasing the hardness of steel through controlled heating and cooling.
HARDNESS:
Resistance to indentation.
HEAT:
An individual batch of metal as it is treated in a furnace.
HEAT TREATMENT:
A combination of heating and cooling operations applied to a metal or alloy to obtain desired microstructure conditions or properties.
HEEL:
Molten steel left in the furnace after tapping.
HOT TOP:
An insulated reservoir on top of an ingot mold that retains heat and holds excess molten metal that is drawn into the ingot as it shrinks.
HOT TOP COMPOUND:
Insulating material placed on top of the molten metal after the mold is filled.
HOT WORKING:
Plastic deformation of metal at specific temperature and rate to prevent strain hardening from occurring.
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I
IMMERSION SAMPLE:
Sample taken directly from the molten steel for chemical analysis.
IMPACT TEST:
A test to determine energy absorption obtained by fracturing a test bar at high velocity.
INCLUSION:
Particles of nonmetallic impurities that are mechanically held in steel during solidification, usually oxides, sulphides, and silicates.
INGOT:
Steel, formerly in a molten state, transferred to an ingot mold to solidify.
INGOT MOLD:
A form into which molten steel is poured to solidify.
IRON:
A pure metal that serves as the basis for steel, cast iron and stainless steel. Iron is relatively weak and soft when in its pure form.
J
JOMINY TEST:
Hardenability test usually performed on alloy steels.
K
KILLED STEEL:
Steel that is deoxidized with a strong deoxidizing agent, such as silicon or aluminum. Reducing the oxygen content minimizes chemical reaction between carbon and oxygen during solidification.
L
LADLE:
A vessel for receiving and handling liquid steel. It is constructed of a refractory-lined steel shell.
LADLE REFINING SYSTEM (LRS):
System where alloys are added to meet exact chemistries, gases are removed by vacuum, and argon bubbles stir the molten mixture to remove impurities and mix the alloying elements. Arc heating maintains steel temperature.
LOW-ALLOY STEEL:
Steel containing up to 5% alloying elements other than carbon.
M
MAKEUP:
Relining ladles or furnace with refractories.
MARTENSITE:
Room temperature structure of steel formed as a result of a rapid quench from the austenitic condition. Hard, strong, and brittle structure.
MECHANICAL PROPERTIES:
Those properties of a material that reveal the elastic and inelastic reaction when force is applied or that improve the relationship between stress and strain.
MELT DOWN:
The process in which steel is transferred from the solid state into the liquid state by introducing electrical power to the scrap in the electric furnace.
MICROSTRUCTURE:
Microscopic structure of steel. Under a microscope, certain elements of the solidified metal are visible (crystal structure).
MODULUS OF ELASTICITY:
A measurement of the stress-per-unit strain, an indication of the resistance of the steel to deformation within its elastic limit.
MOLD:
An iron-casting container used to hold and cool molten metal as it solidifies.
MOLD CLUSTER:
A series of 6 or 8 molds positioned in a circular arrangement interconnected by runners.
MOLD STOOL:
Metal plate used to support each mold on the stool plate.
O
ORE:
A mineral from which the metal can be extracted.
OXIDATION:
Process in which carbon combines with oxygen to form oxides.
P
PLAIN CARBON STEEL:
Iron-carbon alloys with minimal alloy content.
PLASTIC DEFORMATION:
Permanent distortion of a material under the action of applied stresses.
POWDER INJECTION:
The injection of certain materials into the molten bath at the ladle refining station. The material is usually injected through a consumable lance using argon as a carrier gas.
PULPIT:
An enclosed operator’s platform.
Q
QUENCHING:
The process of rapidly cooling the steel from a temperature above the critical temperature.
QUENCH CRACKS:
Cracks formed in a steel part during or after quenching that result from high-stress in cooling.
R
REDUCTION:
Process in which oxygen in removed from a compound.
REFRACTORY:
A substance which is infusible at the highest temperature it may be required to withstand in service; heat-resistant material.
ROCKWELL HARDNESS:
An indentation hardness test that measures hardness by determining, under load, the depth of penetration of an indenter, such as a steel ball. The hardness number is related to the depth of indentation; the greater the number, the harder the material.
RUNNER:
A channel through which molten metal or slag is passed from one receptacle to another.
ROTARY/TEEMING NOZZLE:
Mounted on the bottom of the ladle and used to regulate the flow of molten metal from the ladle into the trumpet.
S
SCALE:
An oxide of iron which forms on the surface of hot steel exposed to air or oxygen.
SCARF:
To remove surface defects from ingots, blooms, or billets, usually with a gas torch.
SCRAP:
Iron or steel discard, cuttings, or raw material which will be reprocessed.
SEAM:
Surface crack on a rolled product which has been closed but not by welding.
SHEAR:
A machine for cutting steel products.
SIDE BOARDS:
Sometimes referred to as hot top. Used to insulate top of mold to avoid large cavity in the top of the ingot as it cools.
SKULL:
A solid piece of steel left in a refractory-lined vessel after use that must be removed in order for the vessel to be reused; mainly used in reference to the ladle.
SLAG:
A crust formed on top of molten steel which primarily acts as an insulator. A medium through which chemical reactions occur across the boundary between the slag and the molten metal.
SOAKING PIT:
A furnace or pit for the heating of ingots to make their temperature uniform throughout in preparation for the rolling operation.
SPALLING:
Breaking away of refractory.
SPIDER:
A refractory brick that distributes the flow of molten metal from the trumpet toward the separate molds.
STAND OF ROLLS:
The simplest unit of a rolling mill, consisting of a set of rolls, the housings, bearings and guides required for the rolling of steel.
STAINLESS STEEL:
High-alloy steel, designed for resistance to corrosion and/or oxidation, containing high percentages of chromium (>4%). Some grades may also contain quantities of nickel.
STEEL:
Iron-based alloy containing carbon and other elements.
STICKER:
An ingot that has not separated from the mold.
STOOL PLATE:
Large metal plate that supports a circular cluster of ingot molds used in the bottom pouring operation. Steel flows down through a central fill tube (trumpet), through grooves (runners) in the bottom of the plate, and up into the ingots through holes in the bottom of the ingots.
STRENGTH:
Ability to resist applied forces.
STRESS:
The load per unit of area.
SURFACE INSPECTION:
The inspection of the surface of products for defects such as ingot cracks, scabs, seams, burned steel, laps, twist, guide marks, etc.
T
TAPPING:
The act of draining the molten metal from furnace to ladle.
TEEMING:
Pouring metal into ingot molds.
TEMPERING:
A process of reheating quench-hardened or normalized steel to a temperature below the transformation range, then cooling at any rate desired. Relieves internal stresses and imparts toughness and ductility.
TENSILE STRENGTH:
A measurement of the maximum load per unit of original area that a steel has prior to fracture.
TOOL STEEL:
Steel with high tempering temperatures with 1/2% to 1-1/2% carbon, significant (75%) alloy content and usually containing carbide stabilizers such as chromium, manganese, molybdenum, vanadium and tungsten.
TOUGHNESS:
Ability to absorb impact energy.
TRUMPET:
A funnel which serves to deliver molten metal to a junction of 6 or 8 runners.
U
ULTRASOUND:
High-frequency sound waves used to detect product defects.
Y
YIELD STRENGTH:
A measurement of the amount of stress that gives the initial significant plastic, or permanent, deformation of the steel.