DIN 6923 Serrated Flanged Hexagon Nuts — Black Oxide Alloy Steel (Class 10)

FULLERKREG DIN 6923 Class 10 serrated hexagon flange nuts with black oxide finish are manufactured from boron alloy steel 10B21, quenched and tempered to achieve Class 10 mechanical properties, conforming to DIN 6923. The boron addition in 10B21 significantly enhances hardenability, enabling superior strength-to-weight performance. The integrated serrated flange bearing surface distributes clamping load over a wider area and provides built-in vibration resistance — eliminating the need for a separate lock washer. Surface finish: black oxide (alkaline hot blackening) with oil post-treatment, providing a uniform matte black appearance with negligible dimensional change — ideal for precision-fit and aesthetics-critical high-strength applications. Thread: metric coarse (ISO 68-1). RoHS compliant.

Dimensional Data — DIN 6923 Serrated Flange Nut (Black Oxide, Class 10)

All dimensions in mm. Unit weight is approximate (calculated at steel density 7.85 g/cm³); actual weight may vary slightly by batch. Tolerances per DIN 6923. Black oxide coating adds negligible dimensional change (< 2.5 µm); no fit adjustment required.

Product Specifications

Material & Mechanical Properties — Boron Alloy Steel 10B21 (Class 10)

Chemical Composition — Boron Alloy Steel 10B21

10B21 is a boron-microalloyed steel. The trace addition of boron (B) dramatically improves hardenability, allowing Class 10 strength to be achieved with lower carbon content than conventional medium carbon steels — reducing hydrogen embrittlement risk while maintaining superior mechanical performance. Black oxide (non-electrolytic) further eliminates hydrogen embrittlement risk associated with electroplating processes.

Surface Treatment — Black Oxide (Blackening)

Black oxide is a conversion coating, not a plating. It does not add meaningful corrosion protection for outdoor or humid environments. For outdoor or marine use, consider zinc-plated (Zn Cr3) or stainless steel (A2 / A4) alternatives. For Class 10 applications where hydrogen embrittlement is a concern, black oxide is preferred over electroplating.

Black Oxide vs Zinc Plated — Class 10 Surface Finish Comparison

Class 10 vs Class 8 vs Class 4 — Strength Comparison

Selection Guide — DIN 6923 Serrated Flange Nut (Class 10, Black Oxide)

Standard Reference

DIN 6923 specifies hexagon flange nuts with a serrated or plain bearing surface. The serrated variant provides mechanical locking through the teeth on the flange underside, which bite into the mating surface under torque — eliminating the need for a separate spring or toothed washer. Class 10 nuts are manufactured from alloy steel and must be quenched and tempered per DIN EN ISO 898-2. Black oxide (chemical blackening) is a non-electrolytic conversion coating process that carries no hydrogen embrittlement risk — making it particularly suitable for Class 10 and above high-strength fasteners. FULLERKREG manufactures to the current edition of DIN 6923 with full dimensional traceability.

Product Gallery

Why FULLERKREG

🏭 Direct Manufacturer — No middlemen. Factory-direct pricing with full production traceability.
📐 DIN Precision — Every batch produced and inspected to DIN 6923 dimensional standards.
🔩 Wide Size Range — M5 through M20 in stock; non-standard sizes available on request.
📦 Flexible MOQ & Packaging — Bulk bags, small boxes, or custom retail packaging to your specification.
🌍 Global Shipping — Direct export from China; experienced with Amazon FBA inbound, sea freight, and air freight.
✅ RoHS & Material Certs — Mill certificates, RoHS declarations, and inspection reports available on request.
🤝 OEM / Private Label — Custom marking, packaging, and labeling for wholesale partners.