Heat treatment classification

Release Date：2013-12-10 00:00 Source：http://www.ksyyc.com Click：

Metal heat treatment technology can be roughly divided into the overall heat treatment, heat treatment and chemical treatment appearance three categories . Based on the heating medium , heating and cooling temperature is not the same way , each category can be divided into a number of different heat treatment technology . The same metal as the heat treatment technology is not selected , a different arrangement can be obtained , and have different functions. Steel is the most widely used industrial metal and steel microstructure arrangement is the most cluttered, so complicated varieties of steel heat treatment technology .

1, the overall heat treatment
Heat treatment is a whole piece all heated and then cooled in an appropriate speed to alter its mechanical features all metal heat treatment technology . Roughly the overall heat treatment of steel annealing , normalizing, quenching and tempering four kinds of fundamental technologies.
Annealing the workpiece is heated to the proper temperature , according to the choice of materials and artifacts scale is not the same insulation moment , and then slowly cooled , the intention is to make the metal internal arrangements to reach or come near balance , achieved outstanding technical features and application capabilities , perhaps in order to further quenching preparatory arrangements . After normalizing the workpiece is heated to a suitable temperature in the air cooled with a role similar to normalizing annealing arrangement only get finer , the data used for improving the cutting function , but also sometimes not high demand for some of the parts as the end of the heat treatment. After quenching the workpiece is heat insulation , rapid cooling in water, oil , or other inorganic salts, organic solution such as quenching medium. After hardened steel hardening, but together brittle. To decrease the brittleness of the steel , the steel after quenching at a temperature above room temperature but below 650 ℃ a proper length of time for incubation, and then cooled , a technique known as tempering . Annealing, normalizing , quenching and tempering heat treatment is all the " four fire" , during the quenching and tempering closely , often co- use , indispensable. "Four fire" followed by heating temperature and cooling methods are not the same , but it turns out is not the same heat treatment technology
. In order to achieve the strength and patience will definitely put quenching and tempering combine technology called quenching . Some alloy constituting the supersaturated solid solution hardening , which was left at room temperature or slightly elevated temperatures persist longer appropriate time to progress the alloy hardness, strength or the like of the magnetic . Such heat treatment technology called aging disposal. Deformation processing and heat treatment of the pressure tight combine useful and for the workpiece to obtain excellent strength , resistance cooperation approach called thermomechanical ; heat treatment in vacuum atmosphere or in vacuum is called vacuum heat treatment, which not only makes workpiece no oxidation, decarbonization , adhere to dispose of the workpiece after the appearance of smooth, progressive piece of functionality , but also through infiltration chemical treatment agents .

2 , the appearance of heat treatment
Heat treatment is the only appearance of the workpiece surface is heated to alter the surface of metal heat treatment technology to its mechanical functions. In order to heat only the surface of the workpiece without causing excessive heat into the interior of the workpiece , using a heat source having a high energy density is required , giving the larger thermal energy per unit area on the workpiece or the workpiece surface portion can be short or transient reach high temperatures. The primary method of heat treatment of the outer flame quenching heat treatment and the induction heating , the heat source used oxyacetylene flame propane or oxygen induced current , laser and electron beam .

3 , chemical treatment
Chemical treatment is through changes in the chemical composition of the surface of the workpiece, the arrangement and function of metal heat treatment technology. Chemical treatment and the appearance of the heat treatment is not the same place which changes the chemical composition of the workpiece surface . Chemical treatment is the workpiece on media containing carbon, nitrogen , or other alloying elements ( gas, liquid, solid ) in heating, insulation a long time , and then the workpiece surface into carbon, nitrogen , boron and chromium and other elements. After entering the elements , and sometimes also for other technologies, such as quenching and tempering heat treatment . The primary approach to chemical treatment of carburizing , nitriding, surface alloying .
Heat treatment is one of the important processes of mechanical parts and tool and die making process . Broadly speaking , it can ensure that the work of the various functions and progress
Such as wear resistance , corrosion resistance and so on. Stress can also improve arrangements and rough conditions , in order to facilitate a variety of cold and hot processing. For example, by long time annealing white iron disposition able to obtain malleable iron, plastic progress
; Gear selection of the correct heat treatment technology , the use of life can be doubled or several times to progress than non- heat-treated gears ; else, inexpensive carbon steel by entering certain alloying elements on the price of expensive alloy steel has some features can replace some heat-resistant steel , stainless steel ; mold is almost full demand by heat treatment before use .

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