Flat discs, normal row ISO 7089-steel 300 HV el. gal thick layer passivated and sealed 4,3

The combination of strength classes for flat washers with those for bolts and nuts is governed by ISO 898-3:2018, Table 1. Washers with a hardness of 300 HV are suitable for applications with heat-treated bolts and nuts (bolts up to 10.9, nuts up to Class 10). Applications involving bolts of strength class 12.9 and nuts of class 12 must be checked during installation.

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.

Conversion coatings (passivation) serve to protect the metal coating against white corrosion. A thick-film passivation in accordance with ISO 4042 offers nine times greater protection against white corrosion than a blue passivation. Additional sealants and/or topcoats, in turn, protect the conversion coating.