Common use cases include:
A brilliant blue surface with a metallic sheen and subtle rainbow iridescence. It is the most visually attractive of all chromate finishes. Corrosion Resistance (Red Rust): According to the standard, Fe Zn 8b must withstand 72 hours in the neutral salt spray test (NSS) before red rust appears (when using Cr(III) based passivations). Electrical Conductivity: The blue film is very thin (approx. 0.1–0.5 µm). Unlike yellow or olive passivations, Fe Zn 8b offers relatively low contact resistance , making it ideal for threaded connections that require electrical grounding (e.g., automotive chassis bolts, electronic enclosures). Weldability: Due to its thin, conductive layer, blue passivated zinc is preferred over thicker coatings for resistance spot welding.
Before diving into "Fe Zn 8b," we must understand the parent standard. is a German industry standard (Deutsches Institut für Normung) titled "Electrodeposited zinc coatings on iron and steel – Terms, testing, and corrosion resistance."
Though DIN 50961 has been officially replaced by ISO 2081, the designation remains a shorthand staple among engineers worldwide. It represents a highly cost-effective, aesthetically distinct, and dimensionally stable method for keeping steel parts functional and free from rust. When utilizing this specification today, ensure your plating partner uses a RoHS-compliant trivalent alternative to achieve the classic yellow passivation without violating modern environmental mandates.
Here's a draft report:
While you still see on drawings, it has been technically superseded by DIN EN ISO 2081 (Metallic and other inorganic coatings – Electroplated coatings of zinc with supplementary treatments).
Because Fe/Zn 8/B offers a clean, aesthetic metallic finish combined with moderate corrosion resistance, it is extensively utilized across several manufacturing sectors:
The technical code specifies an electroplated zinc coating applied to an iron or steel substrate with a minimum thickness of 8 micrometers (
: The minimum local thickness of the zinc coating, which is 8 micrometers ( ) (approximately 0.00031 inches). din 50961 fe zn 8b
(Substrate)
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The DIN 50961 Fe Zn 8b coating is commonly used in various industries, including:
When applying an 8 μ m layer to fasteners, it is crucial to consider the tolerances. A common mistake is not accounting for the increased thickness on threads. The plating thickness can lead to thread interference, especially on fine-thread fasteners or those with tight tolerances (e.g., 2A/2B thread fits), necessitating proper thread allowance calculations. Common use cases include: A brilliant blue surface
The steel parts undergo alkaline cleaning, acid pickling, and rinsing to remove oil, grease, rust, and scale. Proper pre-treatment is essential for adhesion.
If you are looking for the current equivalent to , you should look at ISO 2081.
: Denotes Blue Chromating (also known as clear or transparent passivation). This provides a bright, bluish-clear appearance and light corrosion protection. Typical Performance and Usage