Flügelschrauben ~DIN 316-Stahl verzinkt blau M4x30

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.

Malleable cast iron is a type of cast iron that solidifies without graphite and initially forms as a hard, brittle green cast iron in the mould. Subsequent heat treatment, known as tempering, results in better mechanical properties than those of ordinary cast iron.