(Post-Treatment / Chromate Type)
Zinc protects steel through a process known as galvanic (sacrificial) protection. Because zinc is more chemically active than iron, it corrodes first, shielding the underlying steel even if the coating is scratched or damaged.
To ensure compliance, a DIN 50961 FE Zn 8B coating must pass a series of defined tests outlined in the standard:
Screws, bolts, and fasteners used in moderately corrosive environments. din 50961 fe zn 8b
To ensure the quality of the coating, various tests are performed, including:
To understand exactly what "DIN 50961 Fe/Zn 8b" requires, the alphanumeric string can be broken down into its distinct, standardized components:
The letters immediately following the slash denote the coating metal. stands for Zinc. This indicates that the protective barrier will be formed via zinc electroplating (acidic or alkaline baths) rather than alternative methods like hot-dip galvanizing or mechanical plating. 3. Layer Thickness ( 8 ) (Post-Treatment / Chromate Type) Zinc protects steel through
Minimum 48 to 72 hours before the base steel begins to corrode. Hydrogen Embrittlement Risk
Because an 8-micron coating is relatively thin, it is optimized for parts that require precise dimensional tolerances and mild-to-moderate corrosion defense. You will frequently find this specification used for:
The lowercase suffix is arguably the most important part of the specification. In DIN 50961, the post-treatment suffixes are: To ensure the quality of the coating, various
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The code specifies a technical standard for electroplated zinc coatings on iron or steel. Code Breakdown
The letter signifies the visual and functional finish applied after the zinc plating:
The letters a-d in DIN 50961 refer to the passivation (chromating) type: Transparent/Blue (Clear) b: Yellow/Iridescent c: Olive d: Black
Given the increasing regulatory focus on environmental sustainability, specifying Cr(VI)-free trivalent blue passivation is now standard practice. generally refers to a trivalent blue passivation unless otherwise specified. Chromium(VI)-free passivation treatments are safe and compliant with RoHS and ELV directives; they have no impact on the mechanical properties of fasteners and are necessary for compliance with environmental regulations.