Website Glossary:

Heat-treatment and Metallurgy Terms

  • Alloy – A combination of two or more metals, designed to have properties not found in any single metal.
  • Annealing – A heat-treatment process that alters the properties of a material, typically to increase its ductility and reduce its hardness.
  • Austenite – A solid solution of carbon in face-centered-cubic (FCC) iron, which exists at high temperatures.
  • Bainite – A two-phase microstructure consisting of ferrite and cementite. Formed during certain conditions of isothermal transformation.
  • Carburizing – A heat-treatment process where carbon is introduced into the surface layer of a steel.
  • Cementite – An iron carbide, Fe₃C, which is a hard and brittle phase found in most steels and cast irons..
  • Hardening – The process of making a material harder through heat treatment or alloying.
  • Hardness – The resistance of a material to localized deformation.
  • Heat Treatment – Controlled heating and cooling processes used to change the structure and properties of metals and alloys.
  • Hot rolling – A metalworking process where metals are rolled at temperatures above their recrystallization point.
  • Hypo-eutectoid steel – Steel with less than the eutectoid composition of carbon.
  • Hypo-eutectic alloy – Alloy with a composition less than the eutectic composition.
  • Decarburization – The removal of carbon from the surface layer of a steel when heated in a medium that is not carbon neutral.
  • Ductility – The ability of a material to deform plastically before fracturing.
  • Eutectic – A mixture of two or more phases that solidifies at a constant temperature.
  • Eutectoid – A homogeneous solid solution which, upon cooling, decomposes into two or more new phases at a fixed temperature.
  • Ferrite – A phase of iron and small amounts of carbon, with a body-centered-cubic (BCC) structure.
  • Grain boundaries – The interface separating two grains, or crystallites, in a polycrystalline material.
  • Isothermal transformation – A process in which a material is held at a constant temperature, allowing it to transform structurally over time.
  • Martensite – A very hard metastable structure formed by rapid cooling of austenite.
  • Normalizing – A heat treatment process that involves heating a material and then allowing it to cool in open air.
  • Pearlite – A two-phase lamellar structure in steels, consisting of alternating layers of ferrite and cementite.
  • Phase diagram – A graphical representation showing the equilibrium phases as a function of temperature, pressure, and composition.
  • Precipitation hardening – A heat treatment technique that involves the precipitate formation of a secondary phase to increase strength and hardness.
  • Quenching – Rapid cooling of a material, usually metal, from high temperatures.
  • Recrystallization – The formation of a new set of strain-free and equiaxed grains in a material during heating.
  • Slag – The byproduct, typically consisting of oxides, silicates, and other compounds, that forms during the smelting of ores.
  • Sintering – A process that involves compacting and heating powdered material just below its melting point to form a solid mass.
  • Solution heat treatment – Heating an alloy to a temperature where one or more phases dissolve, then cooling rapidly to obtain a supersaturated solution.
  • Tempering – A process where previously hardened steel or cast iron is heated to a temperature below the critical point, then cooled, to improve toughness.
  • Tensile strength – The resistance of a material to breaking under tension.
  • Thermal expansion – The tendency of a material to change in volume or shape with temperature.
  • Toughness – The ability of a material to absorb energy and deform without fracturing.
  • Transformation temperature – The temperature at which a phase change occurs in a material.
  • Work hardening – The strengthening of a metal or polymer by plastic deformation.
  • Yield strength – The stress at which a material begins to deform plastically.
  • Cold working – Deforming metals below their recrystallization temperature, leading to work hardening.
  • Cryogenic treatment – Treating materials at very low temperatures to improve their properties.
  • Diffusion – The movement of atoms in a material, leading to homogenization.
  • Elastic modulus – The measure of stiffness in a material.
  • Homogenization – A heat treatment process that results in a uniform distribution of the constituents or phases within an alloy.
  • Intergranular corrosion – Corrosion that occurs along grain boundaries, typically because of impurity segregation.
  • Malleability – The ability of a material to be hammered or rolled into thin sheets.
  • Reduction atmosphere – An environment where oxidation is chemically unfavorable.
  • Retained austenite – Austenite that remains at room temperature after quenching, which can impact the steel’s hardness and strength.
  • Solid solution – A homogenous crystalline phase with one or more types of atoms, ions, or molecules in its lattice.
  • Supercooling – Cooling a liquid below its freezing point without it becoming solid.
  • Twinning – A form of plastic deformation which results in a mirror-image reorientation of part of the crystal lattice.

This glossary provides a foundation for those new to heat-treatment and metallurgy. There are many more terms and nuances to explore within the field, and readers are encouraged to delve deeper into specific areas of interest.

ThermTech—Experts in Austempering Stampings, Machined Parts, and Investment Castings

ThermTech, Inc. offers both small and large batch capabilities for austempering steel and iron investment castings. Between our neutral salt bath furnaces and our larger austempering furnaces, we have the capabilities to austemper a wide variety of stamping, machined components, and investment castings. We have run austempering on alloys from 1060 through 4340 to ductile iron machined parts.

Our dedicated team works with you to ensure we meet your specifications. Count on our decades of experience with hardening, tempering, surface heat treatments, vacuum treatments, and annealing. To learn more about our services, please contact us today.

Learn more about austempering and how ThermTech can serve you by watching these videos.

Request a free quote online or call us at 800-752-6917. You can also contact us online for all your austempering and heat treating needs.

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ThermTech’s quality policy is ZERO DEFECTS for all customer products and in all quality management system activities. Through our efforts to continually improve the quality of the work we offer, we’ve been recognized as being able to meet the rigorous quality standards required by several of our major customers. ThermTech is certified for ISO 9001 and AS9100 in both Metal Heat Treat and Metal Finishing.