Malleable cast iron cap screws galvanized blue M8x20

The raw material for malleable cast iron is molten iron containing approximately 3 per cent carbon, 1 per cent silicon and 0.5 per cent manganese. A distinction is made between decarburised malleable cast iron (abbreviation: EN-GJMW) and non-decarburised malleable cast iron (abbreviation: EN-GJMB). Both types of malleable cast iron are considerably tougher than cast iron and are easy to cast. The special grade of malleable cast iron EN-GJMW-360-12 is weldable.

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.