Boriding

Boriding is a thermochemical surface hardening method for producing a wear-resistant surface on a workpiece. It can be applied in almost all steels, cast irons and sintered iron.

The method relies on the introduction of boron into the surface zone of a material at a temperature of between 850 and 950 ° C. The boron may be present in powder or paste form, in which the workpiece is engaged. To a depth of 250 microns a boride layer of FeB and Fe2B which stem -like growing up and having a good anchorage for steel, it also brings an increase in volume of the treated surface zone of approximately 25% with forms. Increasing proportion of all alloying elements in the steel decreases the toughness and the formation of a favorable structure in the boride layer. In unalloyed steels therefore create better and more layers. Likewise, a single-phase layer of the tougher Fe2B is sought. The high process temperature prohibits a Boriding hardened workpieces, and also steel with a high silicon content can not be borated because of the insolubility of carbon and silicon in the boride layer. These elements would be pushed under the boride layer, and a non austenitisierbare ferritic layer could form. The achievable hardness at FeB 2100 HV, at Fe2B 2000 HV.

Footnotes

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