| Aging |
A change in the properties of certain metals and alloys
that occurs at ambient or moderately elevated temperatures after
hot working or a heat treatment. |
| Air-Hardening Steel |
Steel containing sufficient carbon and other alloying
elements to harden fully during cooling in air or other gaseous
mediums. |
| Annealing |
A generic term denoting a treatment, consisting of heating
to and holding at a suitable temperature followed by cooling
at a suitable rate, used primarily to soften metals, but also
to simultaneously produce desired in other properties or in
microstructure. |
| Austempering |
A heat treatment for ferrous alloys in which a work piece
is quenched from the austenitizing temperature at a rate fast
enough to avoid formation of ferrite or pearlite. |
| Brine Quenching |
A quench in which brine is the quench medium. |
| Brinell Hardness |
A hardness number determined by applying a known load
to the surface of the material to be tested through a hardened
steel ball of known diameter. |
| Carbonitriding |
A case hardening process in which a suitable ferrous material
is heated in a gaseous atmosphere of such composition as to
cause simultaneous absorption of carbon and nitrogen by the
surface. Cooling at a rate that produces the desired properties
in the work piece completes the process. |
| Carburizing |
Absorption and diffusion of carbon into solid ferrous
alloys, enabling the surface layer to be hardened either by
quenching directly from the carburizing temperature or by cooling
then reaustenitizing and quenching. |
| Car Furnace |
A batch-type furnace using a car on rails to enter and
leave the furnace area. Car furnaces are used for lower stress
relieving ranges. |
| Case |
That portion of a ferrous alloy, extending inward from
the surface, whose composition has been altered so that it can
be case hardened. |
| Case Hardening |
A generic term covering several processes applicable to
steel that change the chemical composition of the surface layer
by absorption of carbon, nitrogen, or a mixture of the two. |
| Cold Treatment |
Treatment carried out after quenching to transform retained
austenite into martensite, involving cooling and holding at
a temperature below ambient. Often referred to as Cryogenic
Treatment. |
| Continuous-Type Furnace |
A furnace used for heat Treating materials that process
continuously through the furnace, entering one door and being
discharged from another. |
| Core |
In a ferrous alloy prepared for case hardening, that portion
of the alloy that is not part of the case. |
| Cycle Annealing |
An annealing process employing a predetermined time-temperature
cycle to produce specific properties or microstructures. |
| Decarburization |
Loss of carbon from the surface layer of a carbon-containing
alloy. |
| Ferritic Nitro Carburizing |
A process in which both nitrogen and carbon are absorbed
into the surface layer of a ferrous metal at temperatures below
the lower critical temperature. This process is done primarily
to provide an antiscuffing surface layer and improve fatigue
resistance and corrosion. |
| Hardening |
Increased hardness by suitable treatment, usually involving
heating and cooling. |
| Heat Treatment |
Heating and cooling a solid metal or alloy in such a way
as to obtain desired conditions or properties. |
| Homogenizing |
Holding at a high temperature to eliminate or decrease
chemical segregation by diffusion. |
| Induction Hardening |
A surface-hardening process in which only the surface
layer of a suitable ferrous work piece is heated by electromagnetic
induction and immediately quenched. |
| Marquenching |
See martempering |
| Martempering |
A hardening procedure in which an austenitized ferrous
work piece is quenched into an appropriate medium. |
| Microhardness |
The hardness of a material as determined by forcing an
indenter into the surface of a material under very light load.
Usually the indentations are so light they must be measured
under a microscope. |
| Nitriding |
Introducing nitrogen into the surface layer of a solid
ferrous alloy by holding at a suitable temperature in contact
with a nitrogeneous material, usually ammonia or molten cyanide. |
| Normalizing |
Heating a ferrous alloy to a suitable temperature above
the transformation range and then cooling in air. |
| Oil Hardening |
Hardening of carbon steel in an oil bath. |
| Precipitation Hardening |
Hardening caused by the precipitation of a constituent
from a supersaturated solid solution. See aging. |
| Quenching |
Rapid Cooling by various mediums, air, brine, oil, water,
etc. |
| Rockwell Hardness Test |
An indentation hardness test based on the depth of penetration
of a specified penetrator into a specimen under fixed conditions. |
| Solution Heat Treatment |
Heating an alloy to a suitable temperature long enough
to cause one or more constituents to enter into solid solution,
then cooling rapidly enough to hold these constituents in solution. |
| Spheroidizing |
Heating and cooling to produce a spheroidal or globular
form of carbide in steel. |
| Stress Relieving |
Heating to a suitable temperature, holding long enough
to reduce residual stresses, and then cooling slowly enough
to minimize the development of new residual stresses. |
| Surface Hardening |
A generic term covering several processes applicable to
a suitable ferrous alloy that produces a surface layer that
is harder or more wear resistant than the core. |
| Temper |
In heat treatment, reheating hardened steel or hardened
cast iron for the purposes of decreasing hardness and increasing
toughness. |
| Toughness |
The ability of a metal to absorb energy and deform plastically
before fracturing. |
