Heat treatment, quenching tempering anealing normalizing ageing etc

What’s Quenching:

Quenching, also called Hardening is the heating and subsequent cooling of steel at such a speed that there is a considerable increase in hardness, either on the surface or throughout. In the case of vacuum hardening, this process is done in vacuum furnaces in which temperatures of up to 1,300°C can be reached. The quenching methods will differ with regards to the material treated but gas quenching using nitrogen is most common.

In most cases hardening takes place in conjunction with subsequent reheating, the tempering. Depending on the material, hardening improves the hardness and wear resistance or regulates the ratio of toughness to hardness.

What’s Tempering:

Tempering is a heat-treating process applied to metals such as steel or iron based alloys to achieve greater toughness by decreasing hardness, which is usually accompanied by an increase in ductility. Tempering is commonly done after a hardening process by heating the metal to a temperature below a critical point for a certain period of time, then allowing it to cool. Untempered steel is very hard but is often too brittle for most applications. Carbon steel and cold work tool steels are often tempered at lower temperatures, while high speed steel and hot work tool steels are tempered at higher temperatures

What’s Annealing:

Annealing in vacuum

Annealing heat treatment is a process where the parts are heated up and then cooled slowly down to obtain a softer structure of the part and to optimize material structure for subsequent forming steps.

When annealing under vacuum the following benefits are provided in comparision with treating under atmosphere:

Avoiding intergranular oxidation (IGO) and surface oxidation avoiding de-carburized areas metallic, blank surfaces clean surfaces of parts after heat treatment, no washing of parts necessary.

The most popular annealing processes are:

Stress-relief annealing is performed at temperatures about 650°C aiming to reduce the inner stress of the components. These residual stresses are caused by prior process steps such as casting and green machining operations.

Residual stresses can lead to unwanted distortion during the heat treatment process especially for thin-walled components. Therefore it is recommended to eliminate these stresses before the “real” heat treatment operation by stress-relief treating.

Recrystallisation annealing is needed after cold forming operations to gain back the initial microstructure.

What’s Solution and ageing

Ageing is a process used to increase strength by producing precipitates of the alloying material within the metal structure. Solution treatment is the heating of an alloy to a suitable temperature, holding it at that temperature long enough to cause one or more constituents to enter into a solid solution and then cooling it rapidly enough to hold these constituents in solution. Subsequent precipitation heat treatments allow controlled release of these constituents either naturally (at room temperature) or artificially (at higher temperatures).

Furnaces suggeted for heat treatment

Post time: Jun-01-2022