High Tensile Hexagon Flanged Machine Fasteners

High tensile hexagon flanged machine fasteners are engineered to deliver exceptional clamping force and resistance to loosening in heavy-duty mechanical assemblies. These fasteners integrate a hexagonal head and a circular flange that acts as a built-in washer, distributing load over a larger bearing surface. This design reduces the risk of embedment and material damage, making the components particularly effective for structural steel, automotive powertrain, and industrial equipment applications. Within this category, you can find variations such as Hexagonal Bolts With Integral Flange and Stainless Steel Hex Head Bolts With Built-In Flange, both tailored to environments where vibration, thermal cycling, and dynamic stresses are constant concerns. The hex drive provides excellent wrench fit and torque transmission, while the serrated or smooth flange underside adds locking stability without the need for separate washers.

High Tensile Hexagon Flanged Machine Fasteners are manufactured to meet stringent mechanical property standards, typically conforming to ISO 898-1 Class 10.9 and 12.9 or equivalent ASTM grades. The high tensile strength is achieved through carefully controlled heat treatment of alloy steels such as 42CrMo or 40Cr, resulting in core hardness values commonly ranging from 320 to 380 HV. Surface finishes include zinc flake, black oxide, and hot-dip galvanizing to provide targeted corrosion protection for indoor, outdoor, and marine exposure conditions. Thread forms are predominantly metric coarse (ISO 68-1) or unified coarse (UNC), and precision rolling ensures consistent thread geometry for reliable preload retention. These fasteners are widely adopted in flange connections, bearing housings, engine mounts, and pump assemblies where service reliability is non-negotiable.

Key Dimensional and Mechanical Parameters

• Head type: Hexagon with integrated flange (serrated or smooth bearing face)
• Drive size: Standard hex widths per ISO 272, ASME B18.2.3.2M
• Flange diameter: Typically 1.5 to 2.0 times the thread major diameter
• Thread sizes: M5 to M36 (metric), 1/4″ to 1-1/2″ (imperial)
• Length range: 10 mm to 300 mm under head, depending on diameter
• Material: Heat-treated alloy steel (42CrMo, 40Cr, B7 equivalent)
• Strength class: 10.9, 12.9 (ISO), Grade 8, L9 (ASTM)
• Proof load: Up to 970 MPa for Class 10.9, higher for 12.9
• Surface finish: Zinc flake (Geomet®), black oxide, HDG, zinc-nickel
• Thread standard: ISO 261, ASME B1.1, with rolled or cut threads
• Corrosion resistance: Up to 720 hours salt spray for zinc flake finishes