S-91266A549 1/4"-20 x 2" ASTM F835 Alloy Steel Thread-Locking Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Vibration-resistant locking with nylon patch thread locker maintains secure fastening in temperatures from -65° to 250°F, preventing loosening in dynamic environments
• Exceptional durability from black-oxide alloy steel construction providing Rockwell C39 hardness and 130,000 psi tensile strength for heavy-duty applications
• Precise flush mounting with standard 82° countersink angle and flat head design for seamless surface integration
• Reliable thread engagement through Class 3A thread fit and UNC coarse spacing ensuring consistent performance in industrial settings
• Optimized drive efficiency with 5/32" hex drive providing superior torque transmission and reduced cam-out risk
• Partial threading design allows for precise clamping force control and material compression management
• Regulatory compliance meeting ASTM F835 specifications while being RoHS 3 and REACH compliant for global industrial use

Professional Applications & Engineering Value

Engineered for demanding industrial environments, these black-oxide alloy steel flat head screws deliver critical vibration resistance through their integrated nylon patch thread locker, solving common fastener loosening issues in machinery, automotive assemblies, and structural applications. The UNC coarse thread with Class 3A fit ensures rapid installation and reliable performance in various materials, while the 82° countersink angle provides flush surface mounting essential for aerodynamic and safety-critical applications. The partially threaded design allows engineers to precisely control clamping force distribution, making these hex drive screws ideal for equipment requiring both high tensile strength (130,000 psi) and vibration resistance across extreme temperature ranges.

Specification Summary & Compliance

This fastener maintains Class 3A thread fit precision with UNC coarse spacing and partial threading up to 1-1/4" minimum thread length. Manufactured to ASTM F835 specifications with full compliance to RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations. The black-oxide surface treatment enhances corrosion resistance while maintaining the alloy steel's inherent strength characteristics for industrial fastener applications.