Glossary of Material Science

• 1. Tolerance
  

  Tolerance is the allowable deviation from a standard, especially the range of variation permitted in maintaining a specified dimension in machining a piece.

• 2. Temper
  Synonyms: Tempering 
  

  Tempering is a process of heat treating, which is used to increase the toughness of iron-based alloys. Tempering is usually performed after hardening, to reduce some of the excess hardness, and is done by heating the metal to a much lower temperature than was used for hardening

• 3. Hot Rolled
  Synonyms: Tempering
  

  In metalworking, rolling is a metal forming process in which metal stock is passed through a pair of rolls. Rolling is classified according to the temperature of the metal rolled. If the temperature of the metal is above its recrystallization temperature, then the process is termed as hot rolling.

• 4. Annealed
  

  Annealing, in metallurgy and materials science, is a heat treatment that alters a material to increase its ductility and to make it more workable. It involves heating material to above its critical temperature, maintaining a suitable temperature, and then cooling. Annealing can induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties.

• 5. Alloy
  

  Alloys are mixtures of a metal with other elements, the precise combination being governed by the required properties. Alloys can be manufactured by various routes, the most widely used being to melt the constituents together and to cool the resultant mixture to form a single or multi-phase solid.

• 6. UNS
  

  The unified numbering system (UNS) is an alloy designation system widely accepted in North America. It consists of a prefix letter and five digits designating a material composition. A prefix of S indicates stainless steel alloys, C for copper, brass, or bronze alloys, T for tool steels, etc. The first three digits often match older three-digit numbering systems, while the last two digits indicate more modern variations. For example, Copper Alloy No. 377 (forging brass) in the original three-digit system became C37700 in the UNS System. The UNS is managed jointly by the ASTM International and SAE International. A UNS number alone does not constitute a full material specification because it establishes no requirements for material properties, heat treatment, form, or quality.

• 7. ASTM
  

  ASTM International, known until 2001 as the American Society for Testing and Materials (ASTM), is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services.

• 8. Hardness
  

  Hardness is a measure of how resistant solid matter is to various kinds of permanent shape change when a force is applied. Macroscopic hardness is generally characterized by strong intermolecular bonds, but the behavior of solid materials under force is complex; therefore, there are different measurements of hardness: scratch hardness, indentation hardness, and rebound hardness.

• 9. Tantalum Capacitor
  

  A tantalum capacitor is a type of electrolytic capacitor, a component of electronic circuits. It typically consists of a pellet of tantalum metal as anode, covered by an insulating oxide layer that forms the dielectric, surrounded by conductive material as a cathode. Tantalum capacitors are the main use of the element tantalum.

• 10. Superconductivity
  

  Superconductivity is a phenomenon of exactly zero electrical resistance and expulsion of magnetic fields occurring in certain materials when cooled below a characteristic critical temperature.

• 11. Crucible 
  

  A crucible is a container that can withstand very high temperatures and is used for metal, glass, and pigment production as well as a number of modern laboratory processes.

• 12. Tensile Strength
  

  Tensile strength measures the force required to pull something such as rope, wire, or a structural beam to the point where it breaks.

• 13. Flange 
  

  A flange is an external or internal ridge, or rim (lip), for strength, as the flange of an iron beam such as an I-beam or a T-beam; or for attachment to another object, as the flange on the end of a pipe, steam cylinder, etc., or on the lens mount of a camera; or for a flange of a rail car or tram wheel.

• 14. Refractory Metal
  

  A metal or alloy that is heat-resistant, having a high melting point. Typical examples are tungsten, molybdenum, niobium, tantalum, and rhenium.

• 15. Transition Metal
  

  Any of the metallic elements within Groups 3 to 12 in the Periodic Table that have an incomplete inner electron shell and that serve as transitional links between the most and the least electropositive in a series of elements. They are characterized by multiple valences, colored compounds, and the ability to form stable complex ions.

• 16. Yield Strength 
  

  The yield strength or yield point of a material is defined in engineering and materials science as the stress at which a material begins to deform plastically. Prior to the yield point the material will deform elastically and will return to its original shape when the applied stress is removed. Once the yield point is passed, some fraction of the deformation will be permanent and non-reversible.

• 17. Elongation
  

  Elongation is the percentage increase in original length (strain) of a rubber specimen as a result of tensile force (stress) being applied to the specimen. Elongation is inversely proportional to hardness, tensile strength, and modulus.

• 18. HSLA 
  

  Those steel alloys known as high-strength low-alloy (HSLA) steels provide increased strength-to-weight ratios over conventional low-carbon steels for only a modest price premium. Because HSLA alloys are stronger, they can be used in thinner sections, making them particularly attractive for transportation-equipment components where weight reduction is important. HSLA steels are available in all standard wrought forms -- sheet, strip, plate, structural shapes, bar-size shapes, and special shapes.