Serrated flange bolts are precision-engineered fasteners designed to provide secure, vibration-resistant joints without the need for additional washers. Featuring an integrated flange with radial serrations under the head, these bolts create a locking effect that prevents loosening under dynamic loads. Commonly manufactured in stainless steel, carbon steel, and alloy steel grades, they comply with standards such as DIN 6921, ISO 4162, and ASTM specifications for structural fastening.



These bolts are widely used in automotive assemblies, heavy machinery, and structural frameworks where consistent clamping force is critical. The serrations bite into the mating surface, enhancing grip and reducing the risk of joint failure in high-vibration environments.
KK Fasteners supplies serrated flange bolts with full material traceability and dimensional precision, supporting OEMs and EPC contractors across global industrial markets.
| Parameter | Details |
|---|---|
| Material Variants | Stainless Steel (SS 304, SS 316), Carbon Steel (Grade 8.8, 10.9), Alloy Steel |
| Grade Options | A2-70, A4-80, 8.8, 10.9, 12.9 |
| Size Range | M5 to M20 (Metric), 1/4" to 3/4" (UNC/UNF) |
| Thread Type | Metric, UNC, UNF |
| Standards | DIN 6921, ISO 4162, ASTM F568, BS EN ISO standards |
| Surface Finish | Zinc Plated, Hot Dip Galvanized, Black Oxide, PTFE Coated |
| Type Variants | Fully Threaded, Partially Threaded |
| Tensile Strength | Up to 1200 MPa (Grade 12.9) |
|
Nominal |
Width Across Flats (F) |
Width Across Corners (G) |
Flange Diameter (B) |
Flange Thickness (U) |
Head Height (H) |
Hex Height (K) | |||
| Max | Min | Max | Min | Max | Min | Max |
Min |
||
| #8 | 0.2500 | 0.241 | 0.297 | 0.271 | 0.37 | 0.02 | 0.18 | 0.11 | |
| #10 | 0.3125 | 0.305 | 0.367 | 0.340 | 0.45 | 0.03 | 0.21 | 0.13 | |
| 1/4 | 0.3750 | 0.367 | 0.433 | 0.409 | 0.56 | 0.04 | 0.28 | 0.17 | |
| 5/16 | 0.5000 | 0.489 | 0.577 | 0.548 | 0.68 | 0.05 | 0.32 | 0.21 | |
| 3/8 | 0.5625 | 0.551 | 0.650 | 0.618 | 0.81 | 0.06 | 0.39 | 0.25 | |
| 7/16 | 0.6250 | 0.612 | 0.722 | 0.685 | 0.93 | 0.07 | 0.46 | 0.30 | |
| 1/2 | 0.7500 | 0.736 | 0.866 | 0.825 | 1.07 | 0.08 | 0.51 | 0.34 | |
| 5/8 | 0.9375 | 0.922 | 1.083 | 1.034 | 1.33 | 0.10 | 0.62 | 0.42 | |
| 3/4 | 1.1250 | 1.100 | 1.299 | 1.234 | 1.59 | 0.11 | 0.73 | 0.51 | |
Serrated flange bolts are used in applications where vibration resistance and secure clamping are essential, particularly in assemblies exposed to dynamic loads.
Serrated flange bolts are typically produced using cold forging processes followed by precision thread rolling to enhance mechanical strength and fatigue resistance. The serrations are formed with controlled tooling to ensure consistent locking performance across batches.
Quality control includes dimensional inspection using calibrated gauges, tensile and hardness testing, and coating thickness verification. Each batch undergoes traceability checks to ensure compliance with international standards such as ISO 9001, RoHS, and REACH.
At KK Fasteners, inspection protocols include lot-wise documentation and surface finish validation, ensuring that every shipment meets specified engineering and procurement requirements.

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Serrated flange bolts are fasteners with an integrated washer-like flange and serrations under the head. These serrations grip the mating surface to prevent loosening, making them ideal for high-vibration applications where maintaining clamping force is critical.
Stainless steel (SS 304/316) is preferred for corrosion resistance, while carbon steel grades like 8.8 and 10.9 offer higher strength for structural use. Alloy steel grades such as 12.9 are selected for extreme load-bearing applications.
Serrated flange bolts are commonly manufactured according to DIN 6921 and ISO 4162 standards. These define dimensions, tolerances, and mechanical properties to ensure compatibility and performance consistency.
Selection depends on load requirements, environmental exposure, and application type. For high-strength needs, choose grade 10.9 or 12.9; for corrosion resistance, opt for SS 316. Thread type and coating should match assembly conditions.
Look for suppliers with ISO certification, documented quality checks, and global export experience. Reliable manufacturers like KK Fasteners provide material traceability, standard compliance, and consistent production quality.
Serrated flange bolts play a critical role in maintaining joint integrity under vibration and load-intensive conditions. With controlled manufacturing processes and adherence to global standards, KK Fasteners ensures consistent quality across every batch. For project-specific requirements or bulk inquiries, connect with the engineering team to request a detailed quotation or technical consultation.