Mechanical Engineering Materials - Glossary
Stress relief: The process of removing residual stresses from a material. Heat is applied to a limited area at a temperature low enough that the parent materials properties are not altered, then allowed to cool to room temperature. The end result is a reduction in the magnitude of residual stress.
Substrate: A thin layer of material that is used as a base for further working or the deposition of a thin film.
Surface hardening: Changing the surface of the material so that it is harder than the bulk material. This can be achieved by changing the composition of the material, changing the grain size of the material, or a combination of the two processes.
Surface finish: The smoothness or lack of it in a machined or finished surface. It is normally expressed in terms of height or width of the surface irregularities (also known as RMS or LMS values) or the amount of material removed when trying to achieve a smooth surface (lapping, grinding and polishing).
Tensile strength: This is the ultimate strength of the material when subjected to tension. It dictates how much of a load the material can tolerate before breaking.
Thermal shock: A sudden change in temperature that can cause a material to expand and contract rapidly, potentially causing extreme stresses and eventual failure of the material.
Titanium: A light gray metallic element, titanium has very high strength coupled with a low weight. Titanium is well known for its corrosion resistance and is often used in applications which require high performance materials.
Time dependent behavior: The way in which a material behaves over time under a given set of conditions. This can be affected by numerous external and internal factors and will dictate the real-world behavior of the material.
Tool steel: A special type of steel alloy, tool steel is often used for creating tools and dies due to its good wear resistance, hardness, and high strength.
Torque: A measure of the amount of force needed to rotate an object.
Toughness: The ability of a material to absorb energy and deformation before it breaks. It is typically measured in terms of the energy required to cause a notch in the material.
Tungsten: A very hard, brittle, dense material that is used in high temperature and high wear applications due to its toughness and good wear resistance.
Ultimate tensile strength (UTS): Also known as ultimate strength, UTS is the maximum amount of stress a material can take before failure.
Ultrasonic welding: A process used to join two pieces of material together by generating ultrasonic sound waves that cause the two pieces to become one solid material.
Vacuum brazing: A welding process in which two pieces of material, typically of dissimilar metals, are joined together by heating them in a vacuum chamber and using a filler material that melts at a lower temperature than either of the pieces of material being joined.
Vibration: The rapid periodic motion of an object, usually caused by an external force.
Viscosity: The resistance of a material to flow. High viscosity materials are more resistant to flow than low viscosity materials.
Welding: A process in which two pieces of material are joined together by melting the two pieces at their interface and then solidifying the molten material.
Wear resistance: The ability of a material to resist wear due to friction or impact. Higher wear resistance materials are better suited for applications which require frequent contact or friction.
X-ray diffraction (XRD): A technique used to analyze the structure of a material by bombarding it with X-rays. XRD is often used to analyze the crystalline structure of metals and non-metals.
Yield strength: The amount of stress a material can take before it begins to permanently deform. Lower yield strength materials will deform more easily than higher yield strength materials.
Young’s modulus: Also known as the elastic modulus, this is a measure of the stiffness of a material. Higher elastic modulus materials will be stiffer than lower elastic modulus materials.
