heat treatment

(redirected from heat-treating)
Also found in: Dictionary, Medical.

heat treatment

[′hēt ‚trēt·mənt]
(metallurgy)
Heating and cooling a metal or alloy to obtain desired properties or conditions.

Heat treatment (metallurgy)

A procedure of heating and cooling a material without melting. Plastic deformation may be included in the sequence of heating and cooling steps, thus defining a thermomechanical treatment. Typical objectives of heat treatments are hardening, strengthening, softening, improved formability, improved machinability, stress relief, and improved dimensional stability. Heat treatments are often categorized with special names, such as annealing, normalizing, stress relief anneals, process anneals, hardening, tempering, austempering, martempering, intercritical annealing, carburizing, nitriding, solution anneal, aging, precipitation hardening, and thermomechanical treatment.

All metals and alloys in common use are heat-treated at some stage during processing. Iron alloys, however, respond to heat treatments in a unique way because of the multitude of phase changes which can be induced, and it is thus convenient to discuss heat treatments for ferrous and nonferrous metals separately.

Ferrous metals

Annealing heat treatments are used to soften the steel, to improve the machinability, to relieve internal stresses, to impart dimensional stability, and to refine the grain size.

Hardening treatments are used to harden steels by heating to a temperature at which austenite is formed and then cooling with sufficient rapidity to make the transformation to pearlite or ferrite unfavorable.

Some heat treatments are used to alter the chemistry at the surface of a steel, usually to achieve preferential hardening of a surface layer. Carburizing consists of subjecting the steel to an atmosphere of partially combusted natural gas which has been enriched with respect to carbon. In the nitriding treatment, nitrogen diffusing to the surface of the steel forms nitrides. Chromizing involves the addition of chromium to the surface by diffusion from a chromium-rich material packed around the steel or dissolved in molten lead.

Nonferrous metals

Many nonferrous metals do not exhibit phase transformations, and it is not possible to harden them by means of simple heating and quenching treatments as in steel. Unlike steels, it is impossible to achieve grain refinement by heat treatment alone, but it is possible to reduce the grain size by a combination of cold-working and annealing treatments.

Some nonferrous alloys can be hardened, but the mechanism is one by which a fine precipitate is formed, and the reaction is fundamentally different from the martensitic hardening reaction in steel. There are also certain ferrous alloys that can be precipitation hardened. However this hardening technique is used much more widely in nonferrous than in ferrous alloys. In titanium alloys, the β phase can transform in a martensitic reaction on rapid cooling, and the hardening of these alloys is achieved by methods which are similar to those used for steels.

heat treatment

Heating and cooling a solid metal or alloy in order to produce changes in its physical and mechanical properties.
References in periodicals archive ?
Manufacturers are concerned about bottom-line economic issues such as increased cost of WPM, capital outlays for more heat-treating equipment, higher costs resulting from increased energy consumption, and maintenance of markets and customers.
The compact containment area--not much larger than the part undergoing the process--means the procedure is very energy efficient, does not give off excess heat, and does not require the microwave reactor be kept running as is necessary with a heat-treating oven.
The company has recently introduced a second vacuum furnace that is two times the capacity of the largest furnace in its heat-treating department.
Heat treaters have used polymer quenchants in induction heat-treating applications for more than 3 years.
As he sees it, the key trend today is using more robotics to automate heat-treating systems and make them flexible enough to process different types of parts.
This arrangement with Praxair will help us to build on our global presence while providing our customers with the best solutions to meet their heat-treating requirements," said Eric Jossart, vice president of sales for Atmosphere Engineering.
Curtiss-Wright Corporation (NYSE: CW) announced today that its Metal Improvement Company subsidiary has acquired the commercial heat-treating business of privately-held Ironbound Heat Treating Company in Roselle, New Jersey.
0 million to expand its seamless tube-making and heat-treating capacity.
The European Union has adopted new regulations requiring all non-manufactured wood packing materials to meet heat-treating standards.
Together, Delphi and ORNL developed a nickel aluminide fixture casting process, modified the alloy to optimize its manufacturability and performance under typical heat-treating furnace operating conditions, and tested and evaluated prototype parts.
There are many synergistic opportunities to combine the expertise and experience in our heat-treating and processed steel business with SCM to build and strengthen our combined businesses," said Mr.
Acquisition Diversifies Heat-Treating Capabilities, Geographic Reach, and