Oval-head screws fully threaded ISO 4017-12.9 tempered black 2,2x4.2 mm

A further development of Form H are Pozidriv (PZ) screws, standardized in ISO 8764 (blades) and DIN 7962 (Phillips). With the Pozidriv screws, the flanks of the screw head run parallel to each other in the depth of the screw head. Due to the more precise fit, the direction of force is precisely determined and higher torques are possible because the cam-out effect is prevented.

Tempered steel is steel that is given high tensile and fatigue strength through tempering. The toughness is determined by the relationship between hardness and temperature of the subsequent tempering process. It is a transformation hardening in which the ratio of strength to toughness is specifically influenced.

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.