Boron

Boriding is a thermochemical surface hardening process to create a wear-resistant surface on a workpiece. It can be used with almost all types of steel , cast iron and sintered iron .

The process is based on the introduction of boron into the edge zone of a material at a temperature between 750 and 950 ° C. The boron can be present in powder or paste form, into which the workpiece is inserted. A boride layer of FeB and Fe ₂ B forms up to a depth of 250 µm , which grows upwards like a stem and is well anchored to the steel, but also increases the volume of the treated edge zone by approximately 25%. An increasing proportion of all alloying elements in the steel reduces the toughness and the formation of a favorable structure in the boride layer. Better layers are therefore created on unalloyed steels. A single-phase layer made of the tougher Fe ₂ B is also aimed for. The high process temperature prohibits the boriding of hardened workpieces, and steels with a high silicon content cannot be borated because of the insolubility of the carbon and silicon in the boride layer. These elements would be displaced under the boride layer and a ferritic layer which could not be austenitized could form. The achievable hardness is 2100 HV for FeB and 2000 HV for Fe ₂ B.

Footnotes

1. ↑ Wear protection through boriding. Retrieved March 19, 2019 . 
2. ^ Wolfgang Weißbach: Material science and material testing. Vieweg, Braunschweig, Wiesbaden 2000, 13th edition, ISBN 3-528-04019-X , p. 153