Hex socket set screws and pressure studs DIN 6332-5.8 burnished M20x150 mm

Steel is an iron-carbon alloy with a maximum carbon content of 2% by mass. The steels achieve their intended physical and mechanical properties through various hardening, annealing and tempering processes. It is also possible to harden the edge zone by surface hardening, case hardening or nitriding. Well-known steel grades are structural steels, free-machining steels, case-hardening steels, nitriding steels, tempering steels, tool steels and stainless steels.

Blackening is carried out in accordance with DIN 50938. Due to the thinness of the conversion coating – approximately one micrometre – the workpieces retain their dimensional stability to a large extent. Blackened fasteners offer only very limited protection against corrosion. Consequently, this process involves the constant-climate condensation test in accordance with DIN EN ISO 6270-2-CH, as well as the acetic acid and oxalic acid tests.

Compared with a Phillips-head screw of the same size, a hex socket screw can withstand around ten times the torque. Hex socket screws are well suited to bolted joints where the screw heads are difficult to access due to the design of the structure. Hex socket screws can be countersunk to save space if protruding screw heads are a problem.

The number before the point multiplied by one hundred gives the nominal value of the tensile strength in N/mm2, the number before the point multiplied by the number after the point and multiplied by 10 gives the nominal value of the lower yield strength in N/mm2. The number after the decimal point provides information about the yield strength, as a percentage of the tensile strength.