ES Bolzen für Gabelköpfe Stahl verzinkt blau 16x32

Free-cutting steels are described in ISO 683-4. A distinction is made between grades not intended for heat treatment, those intended for case hardening, and free-cutting steels intended for tempering. All steels in accordance with ISO 683-4 are easily machinable (turning, drilling, milling) due to their chip-breaking properties. Tensile strengths range from 310 to 900 MPa, depending on the heat treatment.

Spring steel is a steel that has a higher strength compared to other steels, but with very high elasticity. Tension discs and disc springs are made of spring steel so that the spring forces defined in the standard can be achieved.

Blue galvanised finishes are produced either by electroplating in accordance with DIN EN ISO 4042 or by mechanical plating in accordance with DIN EN ISO 12683. For fasteners with a hardness exceeding 390 HV, there is a risk of hydrogen embrittlement during galvanising (electrolytic process). This necessitates specific measures (such as annealing), although these do not provide a 100 per cent guarantee against embrittlement.