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What exactly is heat treating?
Heat treating is a technology used to harden or soften steel for a desired use. There are many different methods used depending on what needs to be done to the steel. An example would be, does the steel need to be hard all the way through or maybe just hard on the surface? Would it need to be softened so it can be machined or bent? Depending on what needs to be done to the steel also depends on the type of steel.
Back to Top Aluminum Heat Treating
Aluminum can be (1) Annealed which may be required before forming or cold working heat treatable alloys. (2) Solution treating which can put the maximum practical amount of hardening solutes such as copper, magnesium etc. into solid solution in the aluminum matrix. (3) Aging which is done by re-heating the quenched material to a low temperature for a shorter period of time.
Back to Top Annealing
Annealing is a process used to soften steel either for machining or bending. The steel you buy from a foundry maybe pre-hardened and too hard to machine. When it's annealed it will be softer so it can be machined much easier.
Back to Top Austempering
Austempering is a process that is used on certain steels for which it is suitable, and in many cases produces desirable properties not obtainable in any other way. The process consists of heating to proper hardening temperature, quenching in liquid salt to a temperature between 500 to 750 deg F, holding at temperature for several minutes and then cooling in air. A tempering operation is not needed.
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Brazing
Brazing is a process of joining two solid pieces of metal together with brazing material under heat. This fuses both parts together to form a welded seam.
Back to Top Bright hardening & Annealing
Both processes are done in a vacuum furnace to produce the highest level of brightness and cleanliness.
Back to Top Carburizing and Carbonitriding
Carburizing steel adds a hard shell or skin to the surface only. The hard surface can have a range of thickness depending on the applications needs. Carbonitriding is the same process except it used generally for low case depths. By adding ammonia to the atmosphere this produces a slightly harder surface than just carburizing. An example would be that a shaft needs to be hard on the outside for wear resistance but needs to be soft in the core so it can be straightened.
Back to Top Carbon Restoration
Replacing the carbon lost to the surface layer from previous processing by carburizing this layer to substantially the original carbon level.
Back to Top Ferritic Nitrocarburizing
Ferritic Nitrocarburizing processes are thermochemical treatments that involve diffusional addition of both nitrogen and carbon to the surface of ferrous materials at temperatures completely within the ferrite-phase field. Nitrocarburizing is used on a wide range of engineering components, such as rocker arms spacers, textile machinery gears, pump cylinders blocks and jet nozzles.
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Flame Hardening
Flame hardening is a process that can heat treat or anneal a certain area only of a part.
Instead of using an electric coil to heat the part a flame is used to heat the area. An example would be a gear that needs the teeth hardened only instead of the whole part.
Back to Top Glass Beading
Very similar to sandblasting except the media is glass bead. This is not as abrasive as sand and yields a better finish on the part.
Back to Top Induction hardening & annealing
Induction treating is a process that can heat treat or anneal a certain area only of a part. An example would be a gear that needs the teeth hardened only instead of the whole part.
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Martempering & Marquenching
The part is quenched in very hot oil or salt to produce a harder structure and help reduce distortion of the part.
Back to Top Neutral Atmosphere
A neutral atmosphere is based on the grade of steel being treated. The atmosphere does not add or remove any carbon from the surface of the steel.
Back to Top Nitriding
Nitriding is done in an air tight furnace and can produce a much thicker shell than Carburizing.
Back to Top Normalizing
Normalizing is done to help make the grain structure more uniform. It's done by heating to a desired temperature and pulled to air.
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Shot Blasting & Peening
Shot blasting uses steel shot to clean the surface of the steel from rust and heat treat oxidation. Shot Peening is the same process except the parts are blasted for long period of time to relieve stress from the part.
Back to Top Straightening
Straightening of the part can be done in several ways, by plating the part between two steel plates and tightening them together and tempering them at a set temperature. Another way is to press or bend it back to straightness, or to torch the part to desired flatness.
Back to Top Stress relieving
After a part has been machined or welded on it should be stress relieved. This process removes built up stress in the steel. If the part is not stress relieved it takes a chance of cracking or distorting during the heat treat process. Not all steels need to be stress relieved before heat treat; it all depends on the type of steel or what type of heat treating needs to be done.
Back to Top Sub-zero treatments
Steel is lowered to a temperature as low as -120 deg. to remove any retained austenite. This can help produce a higher hardness of the part.
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Through Hardening
Through hardening depends on the grade of steel to be heat treated. Through hardening is done generally in a neutral atmosphere or vacuum furnace. After heat treating the steel should be the same hardness on the surface as in the core +/- a few Rockwell points.
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Vacuum Annealing
Vacuum annealing is a process used to soften steel and keep the part bright and free from oxidation. This is done in a special furnace which pumps out all air which could dull the finish of the steel.
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Vacuum hardening
Vacuum hardening is done is a special vacuum furnace. This furnace works by removing all air and contaminants from the furnace chamber. By doing so this gives the steel a much brighter and cleaner finish after heat treating. Vacuum furnaces are generally used to heat treat tool and die work.
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