Nitriding

Nitriding ( chemically correct actually nitriding ) is fachsprachlich referred to as nitriding ( nitrogen flow analogous to the supply of carbon in carburizing ) and provides a method for hardening steel dar. It belongs in the outline of the manufacturing process to the processes in which the product is produced by modifying the material properties. The usual in the art concept of nitriding or nitriding often leads to misunderstandings, as in chemistry so commonly used to describe procedures that lead to nitrates or nitro compounds. Therefore, it is often advocated for the use of the term nitriding, which has not been implemented so far in practice.

Method

Nitriding is a process for surface hardening. To nitrogen. The result is a surface layer which is resistant to about 500 ° C. Possible methods: Badnitrieren, gas nitriding, plasma nitriding.

The manufacturing process is carried out usually at temperatures of about (500 ... 520) ° C with treatment times of 1 to 100 hours, wherein the core material is ferrite, and also the formation of surface- near- austenite by diffusion of nitrogen is avoided. Forms at the workpiece surface by diffusion of nitrogen or carbon in the workpiece has a very hard superficial connection layer ( ε - and γ' - iron nitride ), depending on the treatment time (10 ... 30) microns can be thick and more or less pronounced Porensäume to having the surface which in turn can be used as a carrier, for example, lubricants. Free compound layer, for example for a subsequent nitriding or chemical plating is possible. Under the compound layer is the diffusion zone in which the nitrogen is stored up to a certain depth in the ferritic matrix metal. This, in solid solution embedded nitrogen leads to an increase in fatigue strength. The so-called " Nitriding Hardness Depth" ( NHD ), ( old name nitriding depth ( case depth ) ) is defined by the hardness limit. The hardness limit is 50 HV above the core hardness of the workpiece. Particularly high hardness in the diffusion zone can be achieved with so-called nitriding.

To increase the corrosion protection of these layers it is possible to oxidize the compound layer. This is usually done by a steam treatment, which can corrode the iron content, thus forming a protective oxide layer.

Current methods are the salt bath nitriding and plasma nitriding. When salt bath nitriding is a partial possible by partially immersing the workpieces in plasma nitriding can be covered mechanically, for example by the clamping device.

Literary processing

In the literature, the smith is mentioned the method in outline in Wieland.