Materials

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Materials are substances or matter that are used to create products or structures.  They can be natural or synthetic, and can exist in various forms such as solids, liquids, and gases.  Materials can have different properties such as strength, flexibility, conductivity, and durability, which make them suitable for different applications.  The study of materials involves understanding the structure, properties, and behavior of materials, as well as their processing and manufacturing methods.

Materials science and engineering is a field that focuses on the development and design of materials for various applications, ranging from everyday consumer products to advanced technologies like aerospace and biomedical devices.  The field also involves the development of new materials with unique properties to address specific challenges or needs.

There are four categories of material: ceramic, composite, metal and polymer.

  • Ceramic  -  Inorganic non-metallic solid comprised of either metal or non-metal compounds made by heating together these materials.
  • Composite  -  Material mixture of two or more materials with different properties combined to produce a new material.
  • Metal  -  Chemical elements that are good conductors of heat and electricity.
  • Polymer  -  A long chain of molecules linked together.

 

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Materials Glossary

A         

  • Abrasion  -  The displacement and/or detachment of metallic particles from a surface as a consequence of being exposed to flowing solids, fluids or gases.
  • Abrasion Resistance  -  Degree of resistance of a material to abrasion or wear.
  • Acid Embrittlement  -  During pickling due to absorption of hydrogen.
  • Aging  -   The term origionally applied to the process or sometimes to the effect of allowing a metal to remain at ordinary temperatures.
  • Air Hardening  -  A hardening process wherein the steel is heated to the hardening temperature and cooled in the air.
  • AISI SAE Steel Numbering System  -
  • Alclad  -   The common name for a type of clad wrought aluminum product with coatings of high purity aluminum or an aluminum alloy different from the core alloy in composition.
  • Alloy  -  A metallic substance consisting of two or more elements, of which at least one is a metal, and in which all elements are miscible in the molten state, and which do not separate when solid.
  • Alloy Steel  -  Steel containing significant quantities of alloying elements other than carbon and the commonly accepted amounts of manganese, silicon, sulfur, and phosphorus.
  • Alloying Elements  -  Chemical elements constituting an alloy.  In steel, usually the elements added to modify the properties of the steel.
  • Annealing  -   A heating and controlled cooling operation to impart specific desirable properties generally concerned with subsequent fabrication of the alloy.
  • Austenite  -  A solid solutionin which gamma iron is solvent, having a face-centered cubic crystal structure.
  • Austenite Steel  -  Steel, which due to its composition has a stable structure at normal (room) temperature.

B         

  • Bake  -  Heat in an oven to a low controlled temperature to remove gases or to harden a binder.
  • Batch Over  -  Oven use to bake a number of cores at one time.
  • Bent Test  -  A test commonly used to determine relative ductility of a sample by bending it over a given radius through a given angle.
  • Blacking Carbon  -  Carbonaceous materials such as plumbago, graphite or powdered coke usually mixed with a binder and frequently carried in suspension in water or other liquid; used as thin facing applied to surfaces of molds or cores to improved casting finish.
  • Blister  -  A shallow blow with a thin film of the metal over it appearing on the surface of a casting.
  • Bimetal  -  Casting, usually centrifugal, made of two different metals, fused together.
  • Bond Strength  -  Property of a foundry sand to offer resistance to deformation.
  • Brass  -  A copper-base alloy in which zinc is the principle added element.
  • Bright Annealing  -  A process carried out usually in a controlled furnace atmosphere, so surface does not oxidize, remaining bright.
  • Brinell Hardness Number  -  A value assigned to the hardness of metals and alloys.  To do this a steel ball is pressed into the surface of an object by a known load to deform the material.
  • Brittle Fracture  -  Fracture with little or no plastic deformation. Smoothing machined holes or outside surfaces of castings by drawing, pushing on, or more broaches, special cutting tools, through the roughed out hole.
  • Bulk Density  -  The ratio total weight of soil to the total volume of soil.
  • Burnishing  -  Developing a smooth finish on a metal by tumbling or rubbing with a polished hand tool.

C         

  • Capacitance  -  The ability to hold an electric charge.
  • Capacitor  -  Behaves as a charge storage device.  Holds an electric charge when voltage is applied across it and gives up the stored charge when required.
  • Carbon Steel  -  A metal alloy, a combination of two elements, iron and carbon, where other elements are present in quantities too small to affect the properties.
  • Carburizing  -  Diffusing carbon into the surface of iron-base alloys by heating in the presence of carbonaceous materials.
  • Case Hardening  -  Carburizing, nitriding, or cyaniding and subsequent hardning by suitable heat treatment.
  • Casting  -  Pouring molten metal into a mold or a metal object.
  • Cementita  -  An iron-carbon compound with the chemical formula \(Fe_3C\) often called iron carbide.
  • Chemical Analysis  -  Seperating an alloy into its component elements and identifying them.
  • Chromium  -  A hard crystaline metal used as an alloying element to give resistance to heat, corrosion, and wear and increase strength and hardenability.
  • Cleanroom  -  A room/facility in which the air supply, air distribution, filtration of air supply, materials of construction, and operating procedures are regulated to control airborne particle concentrations to meet approperate cleanliness levels.
  • Cold Working  -  Permanent deformation of a metal below its recrystallization temperature.
  • Composite Material  -  A combination of two materials with different chemical and physical properties.
  • Compressive Strength  -  The ability to withstand compressive stresses.
  • Compressive Stress  -  Stress caused by a compressive load or in fibers compressed by a bending.
  • Conductor  -  A material through which heat passes and allows the free flow of electric charge.
  • Cooling Curve  -  A curve showing the relationship between time and temperature during the solidification and cooling of a metal sample.  Since most phase changes involve evolution or absorption of heat, there may be abrupt changes in the slope of the curve.
  • Cooling Stress  -  Stress caused by uneven contraction, external restraint or localized plastic deformation during cooling.
  • Cope  -  Upper or topmost section of a flask, mold or pattern.
  • Core  -  A performed sand aggregate inserted in a mold to shape the interior or that part of a casting which cannot be shaped by the pattern.
  • Core Binder  -  Any material used to hold the grains of core sand together.
  • Core Blow  -  A gas pocket in a casting adjacent to a core cavity caused by entrapping gases from the core.
  • Core Compound  -  A commercial mixture used as a binder in core sand.
  • Core Hardness  -  The ability of a core to resist scratching or abrasion.
  • Corrosion  -  The thinning of a pipe wall that is typically caused by a chemical reaction from a corroding fluid or agent and is limited almost exclusively to metal products.
  • Creep  -  Plastic flow of metal, usually occuping at high temperatures, subject to stress appreciably less than its yield strength.
  • Crucible  -  A container that can withstand very high temperatures and is used for metal, glass, and pigment products.
  • Crucible Furnace  -  A furnace fired with coke, oil, gas, or electricity in which metals are melted in a refractory crucible.
  • Cyaniding  -  A process of case hardening a ferrous alloy by heating in a molten cyanide salt bath, thus causing the alloy to absorb carbon and nitrogen simultaneously.

D         

  • Ductility  -  That property of metal which allows the metal to be permanently deformed before final rupture.

E         

  • Elasticity  -  Measures the stiffness of an elastic material.  Elasticity can deformed body and return to its original shape when the forces exerted are removed.
  • Elastic Limits  -  Maximum stress that can be applied to a metal without causing plastic deformation that will remain after the load is relaxed to zero.
  • Electrode  -  An electrical conductor used to contact a nonmetallic part of a circuit.
  • Electron  -  A subatomic particle found in all atoms, electrons carry electricity by flowing from one atom to the next in a conductive material.
  • Elongation  -  The increase in length to which a material is to be stretched prior to rupture.
  • Endurance Limit  -  A limit of stress below which metal will withstand fracture.
  • Eutectoid Steel  -  A carbon steel containing 0.80% carbon becomes a soild solution at any temperature in the austenite temperature range between 1333 F and 2500 F.

F         

  • Fatigue  -  The tendency of a metal to fracture under conditions of repeated cyclic stressing below the ultimate tensile strength but above the yield strength.
  • Ferrite  -  A solid solution in which alpha iron is the solvent and having a body-centered cubic crystal structure.
  • Ferrite Steel  -  Steel which, due to its composition, is not hardenable by heat treatment.
  • Ferrous Metal  -  Mostly contain iron.
  • Free Machining  -  That property of steel imparted by additions of sulfur, selenium or phosphorous which promote chip breakage and permit increased machining speeds.

G         

  • Galling  -  The damaging of one or both metallic surfaces by removal of particles from localized areas during sliding friction.
  • Grains  -  Individual crystals in metal.

H       

  • Hardenability   -  In a ferrous alloy, the property that determines the depth and distribution of hardness induced by heat treating and quenching.
  • Hardening Precipitation  -  Hardening of metallic alloys, by aging, which results from the precipitation of a constituent from a super-saturated solid solution usually non-ferrous alloys.
  • Hardness  -  The property of a material that enables it to resist plastic deformation, usually by penetration.  However, the term hardness may also refer to resistance to bending, scratching, abrasion or cutting.
  • Heat Treatment  -  The heating and cooling of metals or alloys.
  • Homogenizing  -  A process of heat treatment at high temperature to eliminate or decrease chemical segregation by diffusion.
  • Hooke's Law   -  Stress is proportional to stress in the elastic region.
  • Hot Forming  -  Working operations performed on metals heated to temperatures above room temperature.
  • Hot Rolled  -  A metal forming process in which metal stock is passed through a pair of rollers.
  • Hot Working  -  Hot forming above the recrystallization temperature.
  • Hydrogen Embrittlement  -  A brittleness sometimes engendered by contact with plating and pickling solution acid due to absorption of hydrogen by the metal.
  • Hypereutectoid Steels  -  Steel containing from 0.80% to above 2.0% carbon.
  • Hypoeutectoid Steels  -  Steel containing less than 0.80% carbon.

I         

  • Impact Test  -  A test designed to determine the energy absorbed in fracturing a test bar.

J

K         

  • Kerf Loss  -  The amount of material loss during a cutting process.
  • Killed Steel  -  Steel in which sufficient deoxidizing agents have been added to prevent gas evolution during solidification.
  • Knoop Hardness Number  -  The calculated result from a Knoop hardness test, which is proportional to the test force applied to the Knoop indenter divided by the projected area of the permanent indentation made by the indenter after removal of the test force.
  • Knoop Hardness Test  -  An indentation test in which a Knoop rhombic based pyramidal diamond indenter having specified edge angles, is forced under specified conditions into the surface of the test material, and, after removal of the test force, the length of the long diagonal of the projected area of the indentation is measured to calculate the Knoop hardness number.

L         

  • Levitation  -  Separation of fine powder from coarse material by forming a suspension of the fine material in a liquid.
  • Levitation Melting  -  An induction melting process in which the metal being melted is suspended by the electromagnetic field and is not in contact with a container.

M         

  • Magnetic Particle Testing  -  A method of inspection consists in suitable magnetizing the material and applying a prepared magnetic powder which adheres along lines of flux leakage.
  • Martensite  -  An unstable constituent in quenching steel, the hardest of the transformation products of austenite.
  • Martensitic Steel  -  Steel which, due to its composition, has martensite as its chief constituent after cooling.  The hardenable stainless types are all martensite steels.
  • Mask  -  A patterned layer of material used to prevent the etching of the material directly beneath it.
  • Mechanical Properties  -  Those properties that reveal the reaction, elastic or plastic, of a material to an applied stress, or that involved the relationship between stress and strain.
  • Melting Point  -  A solid is the temperature at which it changes state from solid to liquid.

N         

  • Normalizing  -  A process in which a steel is heated to a suitable temperature above the transformation range and is subsequently cooled in still air at room temperature.

O         

  • Oil Quench  -  A quench from the hardening temperature, in which oil is the cooling medium.
  • Olsen Test  -  This is a cupping test made on an Olsen machine as an aid in determining ductiity and deep drawing properties.
  • Overheating  -  Heating to such a temperature that while the properties of the metal are impared, it has not been burned and can therefore be restored by heat treatment.

P         

  • Physical Properties  -  Those properties familiarly discussed in physics, for example, density, electrical conductivity, and thermal expansion coefficient, exclusive of those described under mechanical properties.
  • Pickling  -  Immersion in dilute acid or other suitable media for the removal of oxide scale from hot-rolled or otherwise sealed surfaces.
  • Pitting Resistance Equivalent Number (PREN)  -  PERN is a way to measure the pitting corrosion resistance of various types of stainless steel in a chlorine based environment. 
  • Plasticity  -  The ability of a metal to be deformed extensively without rupture.
  • Plating  -  Deposition of a thin film of a metal or alloy on a different base metal from a solution containing ions of the plating metal.
  • Plating Rack  -  A fixture used to hold work and conduct current to it during electroplating.
  • Poisson's Ratio  -  The elastic ratio between lateral strain and longitudinal strain.

Q         

  • Quenching  -  The fast cooling of metals or alloys for the process of hardening.  This process can be done with air, oil, or water.  If the metal cools too quickly due to a large flow of heat into the thick base plate, the weld may become brittle, having low fracture toughness.
  • Quenching Medium  -  The m,edium used for cooling steel during heat treatment, usally air, oil, salt, or water.
  • Quenching Temperature  -  The temperature from which steel is quenched during a heat treating process.

R         

  • Radiography  -  The use of X-rads or gamma radiation to detect internal structural defects in metal objects.
  • Refractory  -  Any material that has an unusually high melting point and that maintains its structural properties at very high temperatures.  Composed principally of ceramics, refractories are employed in great quantities in the metallurgical, glassmaking, and ceramics industries, where they are formed into a variety of shapes to line the interiors of furnaces, kilns, and other devices that process materials at high temperatures.
  • Refractory Metals  -  Metals such as tungsten, columbium, tantalum, molybdenum, which have relative high melting temperatures.
  • Resilience Modulus  -  The amount of energy a material can absorb and still return to its origional shape.
  • Rockwell Hardness Test  -  Forcing a cone-shaped diamond or hardened steel ball into the specimen being tested under standard pressure.  The depth of penetration is an indication of the Rockwell Hardness.

S         

  • Shear Modulus  -  The ratio of the tangential force per unit area applied to a body or substance to the resulting tangential strain within the elastic limits.Shear Stress  - Tends to deform the material by breaking rather than stretching without changing the volume by restraining the object.
  • Specific Heat  -  The amount of energy required to increase one gram of a substance by 1 degree celsius.
  • Stiffness  -  The resistance of the elastic deformation of an object that applies to both compression and tension.
  • Superconductivity  -  A phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occuring in certain materials when cooled below a characteristic critical temperature.

T         

  • Temper  -  The amount of hardness that an alloy has after cold working or heat treatment.
  • Temper Brittleness  -  Brittleness that results when certain steels are held within or slowly cooled through a certain range of temperature below the transformation range.
  • Temper Stress  -  Quenching in water from the tempering temperature to improve fatigue strength.
  • Tensile Strength  -  The maximum stress a material can resist before it starts to elongate.
  • Thermal Conductivity  -  The ability to transfer heat within a material without any motion of the material.
  • Thermal Expansion Coefficient  -  The percentage change in the length of the material per degree of temperature change, heated solid or liquid.
  • Thermal Stress  -  Resulting from non uniform distribution of temperature.

U         

V         

  • Vacuum Hot Pressing  -  A method of processing materials, especially metal and ceramic powders, at elevated temperatures, consolidation pressures, and low atmospheric pressures.
  • Vacuum Melting  -  A process by which alloys are melted in a near-perfect vacuum to prevent contamination by atmospheric elements.
  • Vickers Hardness Number  -  The calculated result from a Vickers hardness test, which is proportional to the test force applied to the Vickers indenter divided by the surface area of the permanent indentation made by the indenter after removal of the test force.
  • Vickers Hardness Test  -  An indentation test in which a Vickers square-based pyramidal diamond indenter having specified face angles is forced under specified conditions into the surface of the test material, and, after removal of the test force, the lengths of the two diagonals of the projected area of the indentation are measured to calculate the Vickers hardnessnumber.
  • Viscosity  -  The measure of the internal friction/resistance to the flow of a liquid.

W         

  • Water Quench  -  Cooling steel from its quenching temperature with water.
  • Welding  -  A fabrication process that fuses like materials togeather by heating them to a suitable temperatures, this can be acomplished by brazing, soldering or welding.

X

Y         

Z

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