(Also called Precipitation Hardening)
A change in the properties of certain steels, and structural alloys, that occurs at ambient or moderately elevated temperatures after hot working or a heat treatment (quench aging, natural aging, or artificial aging) or after a cold-working operation (strain aging).
Annealing is used to induce ductility, soften material, relieve internal stresses, refine the structure by making it homogeneous, and improve cold working properties.
A thermal process that produces significantly tougher parts than conventional heat treating. Used in many applications where distortion is critical. The resultant microstructure is very tough, exhibiting 15% higher toughness than a quench & tempered part of the same hardness.
Case hardening in which a suitable steel object is heated above Ac1 in a gaseous atmosphere of such composition as to cause simultaneous absorption of carbon and nitrogen by the surface and, by diffusion, to create a concentration gradient.
A process in which an austenitizable steel object is brought into contact with a carbonaceous environment of sufficient carbon potential to cause absorption of carbon at the surface and, by diffusion, to create a concentration gradient.
(Also called Cold Treatment)
Cryogenics, or deep freezing is done to make sure there is no retained Austenite during quenching, resulting in a complete Martensitic microstructure.
Ferritic nitrocarburizing is a range of case hardening processes that diffuse nitrogen and carbon into ferrous metals at sub-critical temperatures.
A process in which a suitable steel object is heated by electromagnetic induction to above the upper critical temperature, and then the object is immediately quenched.
Mag Particle Inspection
A non-destructive testing (NDT) process for detecting surface and subsurface discontinuities in ferroelectric materials such as iron, nickel, cobalt, and some of their alloys.
(Also called Martempering)
A hardening procedure in a molten salt bath at a temperature right above the martensite start temperature that follows the austenitization of the ferrous material.
Introducing nitrogen into a solid steel object by holding it at a suitable temperature in contact with a nitrogenous environment.
Heating a steel object to a suitable temperature, holding it long enough to reduce residual stresses, and then cooling it slowly enough to minimize the development of new residual stresses.
Reheating a quench hardened or normalized steel object to a temperature below Ac1, and then cooling it at any desired rate.
Vacuum Heat Treat
Heating metals to high temperatures normally causes rapid oxidation, which is undesirable. A vacuum furnace removes the oxygen and prevents this from happening.