Glossary

Alfa Chemistry provides you with a glossary of terms commonly used in the metallurgical industry. If you are interested, please read on.

A
Abrasion
The process of scraping or wearing something away.
Abrasion Resistance
Abrasion resistance refers to the ability of materials and structures to withstand abrasion.
Aging
Changes in the properties of metals and alloys, which occur slowly at room temperature, will proceed rapidly at higher temperatures.
Air-Hardening Steel
Air-hardening steel refers to steel that undergoes the process of using air as a quenchant.
Alclad
Alclad is a sheet of aluminum specifically designed for corrosion resistance.
Alloy Steel
Alloy steel is a type of steel with alloying elements other than carbon added to improve its properties.
Aluminizing
Aluminizing is a high-temperature chemical vapor deposition (CVD) process whereby aluminum vapors diffuse into the surface of the base metal, forming new metallurgical aluminide alloys.
Alpha-ferrite
Alpha-ferrite is a body-centered cubic structure phase of iron that exists below temperatures of 912 °C for low concentrations of carbon in iron.
Ambient Temperature
Ambient temperature is the air temperature of an environment or object.
Annealing
Annealing is a heat treatment process used mostly to increase ductility and reduce the hardness of a material.
Argon Oxygen Decarburization (AOD)
AOD is a process primarily used in production of stainless steel and other high grade alloys.
Atomic-Hydrogen Welding
Atomic-hydrogen welding is a specialized welding technique used for metalworking.
Austempering
Austempering is the process of heat treatment where the steel is heated to austenitizing temperature, held there for sufficient period of time to produce homogeneous austenite.
Austenite
Austenite, also known as gamma-phase iron (γ-Fe), is a non-magnetic face-centered cubic structure phase of iron.
Austenitizing
Austenitizing is one of the heat treatment processes of steel and other ferrous alloys where these materials are heated above their critical temperatures long enough for transformations to take place.
B
Bainite
Bainite is an acicular microstructure (not a phase) that forms in steel at a temperature of about 250-550°C (depending on the alloy content).
Bearing Load
A compressive load supported by a member, usually a tube or a collar, along a line where contact is made with a pin, rivet, axle, or shaft.
Bearing Strength
Bearing strength is a measure of the maximum stress that soil can withstand before it deforms and fails.
Bend Test
The bend test is a simple and cheap qualitative test that can be employed to evaluate both the ductility and soundness of a material.
Bent Radius
The bent radius is the inside radius of a bent section.
Billet
A billet is a small, semi-finished piece of metal that is rectangular, circular, or square in shape.
Blue Annealing
Softening metal sheets by heating in an open furnace and cooling in air; bluish oxide forms on the metal surface.
Blue Brittleness
Blue brittleness is a strain aging mechanism that occurs in this blue heat temperature range.
Box Annealing
Annealing a metal or alloy in a sealed container under conditions that minimize oxidation.
Bright Annealing
Bright annealing is an annealing process performed in a vacuum or a controlled atmosphere containing inert gases (such as hydrogen).
Brinell Hardness Test
Brinell hardness test measures the diameter of the indentation to calculate the hardness value. It is commonly used to determine the hardness of materials like metals and alloys.
Brittle Fracture
Brittle fracture is the fracture that occurs in material with very little or no plastic deformation.
Burnishing
Burnishing is a chipless machining method which cold works the metal without cutting or abrading the surface.
C
Capped Steel
Capped steel is a type of steel formed by limiting gas generation in its granular structure, therefore making it an intermediate steel between rimmed and killed steel types.
Carbon Steel
Carbon steel, a carbon and iron alloy, is widely used in the oil and gas production industry because of its availability, constructability, and relatively low cost.
Carburizing
Carburizing is a case hardening process in which carbon diffuses into the surface layer of a steel part at a temperature high enough to change the steel grain structure. Carburizing is typically performed after a part has been constructed to its final form.
Case Hardening
Case hardening is a heat treatment technique in which a metal surface is reinforced by the adding of a thin layer of another metal alloy that is more durable, increasing the object's life.
Cementite
Cementite consists of iron and carbon compounds combined chemically, having the chemical symbol Fe3C. It is a high hardness carbide phase with a more complex orthorhombic crystal unit cell.
Charpy Impact Test
The Charpy impact test, also known as the Charpy V-notch test, is a standardized high strain-rate test. The purpose of this test is to understand the impact energy and determine the impact strength of the desired material.
Chemical Milling
Chemical milling is the subtractive machining process using baths of temperature-regulated etching chemicals to remove material for producing the required shape.
Cold Work
Cold work involves any metalworking process where the alloy is plastically deformed below its recrystallization temperature.
Compressive Strength
Compressive strength is a useful way of measuring how much load a surface or material can withstand.
Corrosion Fatigue
Corrosion fatigue occurs when metal components exposed to corrosive environments are subjected to cyclic stress.
D
Decarburization
Decarburization is a loss of carbon in the surface-adjacent zone of the material. This problem is mainly found in high carbon steels and tool steels.
Drop Forging
Drop forging is a metal shaping process that can be used to improve the strength of a material.
Ductility
Ductility is the capacity of a material to deform permanently in response to stress.
E
Eddy Current Testing
Eddy current testing is an important non-destructive testing technique that uses electromagnetism to detect flaws in materials.
Elastic Limit
Elastic limit refers to the maximum value of stress or force for which a material shows elastic behaviors.
Elasticity
Elasticity is the ability of a deformed material body to return to its original shape and size when the force causing the deformation is removed.
Elongation
Elongation is the amount that a material permanently lengthens when experiencing a tensile force.
F
Fatigue
The loss of load-bearing ability of a material under repeated load application, as opposed to a single load.
Fatigue Life
Fatigue life is the number of loading (stress or strain) cycles of a specified character that a specimen sustains before failure of a specified nature occurs.
Fatigue Limit
The fatigue limit can be defined as the number of cycles that a material survives with a given stress amplitude.
Fatigue Strength
The fatigue strength of a material is defined as the highest stress value that a material can be subjected to for a specified number of cycles without resulting in failure.
G
Galling
Galling is a type of wear that occurs when materials that are compressed against one another are put into motion that causes friction.
Galvanic Corrosion
Galvanic corrosion is an electrochemical process that occurs when electrons can flow freely between two different materials with sufficiently different electrical potentials.
H
Hardenability
The hardenability can be described as the ability of a material to be hardened when it is exposed to heat and then quenched or cooled rapidly.
Hardening
Hardening is a metallurgical metalworking process used to increase the hardness of a metal.
Hot Shortness
Hot shortness is a type of welding defecting characterized by the cracking of a material along its grain boundaries as the welded area cools and solidifies.
I
Impact Test
Impact test determines the amount of energy absorbed by a material during fracture.
Izod Impact Test
The Izod impact test is a standard test that measures the impact energy needed to fracture a material.
L
Low-Hydrogen Electrode
A low hydrogen electrode is an electrode used in welding that has a lower content of hydrogen than other types of electrodes. Using a low hydrogen electrode can help prevent cracking of the weld metal.
M
Magnetic Particle Inspection
Magnetic particle inspection is a simple non-destructive testing method. It helps to detect surface and subsurface faults and discontinuities in ferromagnetic metals and their alloys.
Martempering
Martempering is the process of interrupted quenching from austenitizing temperature in stainless steels, alloys, cast and tools.
Martensite
Martensite is a phase that forms when certain alloys are cooled through and below a critical temperature.
Modulus of Elasticity
Modulus of elasticity is the measure of the stress–strain relationship on the object.
Q
Quenching
Quenching is the process of rapidly cooling a material in order to obtain desirable mechanical properties.
S
Stress Corrosion Cracking
Stress corrosion cracking is a phenomenon of metal or alloy failure caused by the combined action of stress and corrosion.
T
Tack Welding
Tack welding is a quick pre-welding process of applying small dot-like beads throughout the joint's length.
Temper Embrittlement
Temper embrittlement is inherent in many steels and can be characterized by reduced impact toughness.
Y
Yield Point
Yield point is the material property defined as the stress at which a material begins to deform plastically.
Yield Strength
Yield strength is a measurement of the greatest stress that a material can withstand without deforming plastically.