Key rings Steel nickel-plated 20

The steel hardening process aims to change the internal structure of the material through controlled heat treatment. By heating to temperatures above 780°C, the steel is converted to the austenite state, and then rapid cooling (quenching) occurs.

Nickel coatings are produced either by electroplating in accordance with DIN EN ISO 4526 or by chemical processes in accordance with DIN EN ISO 4527. In the case of electroplating, there is a risk of hydrogen embrittlement in fasteners with a hardness exceeding 390 HV. This necessitates specific measures (such as annealing), although these do not provide a 100 per cent guarantee against embrittlement.