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Stress-relief annealing is necessary when existing residual stresses have a detrimental influence on distortion behavior during hardening. Corrections of the resulting changes in shape and size are taken into consideration by adding a certain machining allowance. The temperature must be below the Ac1 transition temperature but should nevertheless be as close as possible to this temperature so that it is not necessary to maintain the temperature after heating. Heating and cooling must be carried out in such a way that no additional or new residual stresses can develop. In the case of cold-formed tools, the normalizing process is preferred, whereas in the case of stress-relief annealing, coarse grain formation might occur as a result of re-crystallization.

Hardening with subsequent tempering, mostly above 550°C, to reach a desired combination of mechanical properties, in particular to increase the toughness compared to the hardened condition.

Hardening serves to achieve a high hardness in the component, preferably by martensite accumulation. It consists of the following two stages: austenitizing and cooling at an adequate speed.

Process to increase stability by accumulation caused by precipitation. It consists of the solution treatment and precipitation heat treatment sub-processes.

A single or repeated heating of a hardened component to a pre-determined temperature (<ac1), maintenance of the given temperature and subsequent adequate cooling.

In the soft annealing process, heat treatment takes place to achieve the lowest possible hardness with high malleability at the same time. By heating and maintaining the temperature in the range of the Ac1 transition temperature for several hours, hardening structure constituents and strain hardening are eliminated and the cementite fins of the pearlite take on a spheroid form (this is also referred to as annealing to achieve spheroidal carbides). In most cases the soft annealed condition is the most suitable form for machining and cold forming as well as hardening. Exceptions are steels with lower carbon contents that tend to “smear” when being turned or milled.

Consists of heat treatment to austenitize the steel, together with subsequent cooling in calm air.

Like stress-relief annealing, the purpose of structural heat treatment is to disperse stresses caused by machining the material; the process is normally carried out after rough machining. The treatment consists of hardening followed by soft annealing. As a result of the change in structure, reduced changes in shape and dimensions can be anticipated during subsequent heat treatment.

A dark blue-grey-black oxide layer (magnetite) is deposited on the surface of the tools during steam tempering. As well as changing the optical appearance, steam tempering improves corrosion-resistance and minimizes the coefficient of friction.

Treatment after hardening to convert a large amount of the residual austenite to martensite. The treatment consists of a cooling process and the maintenance of a given temperature below room temperature.