S-91253A564 1/4"-20 x 3 1/2" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 130,000 psi ensures reliable performance under heavy loads and vibration, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance from the black-oxide finish on alloy steel, extending service life and maintaining integrity in harsh industrial environments.
• Precise Class 3A thread fit provides tighter tolerances for secure fastening, minimizing loosening and improving assembly reliability.
• UNC coarse threading enables quicker installation and better performance in materials where fine threads might strip or cross-thread.
• 82° countersink angle and flat head design allow for a flush finish, enhancing aesthetics and safety by eliminating protrusions.
• Hex drive (5/32") offers high torque transfer and slip-resistant engagement, speeding up assembly and disassembly with standard tools.
• Partial threading provides unthreaded shank for added shear strength, ideal for applications requiring clamping force without thread engagement.

Professional Applications & Engineering Value

Engineered for industrial fastening where durability and precision are critical, these black-oxide alloy steel flat head screws address common challenges like corrosion, high-stress fatigue, and assembly efficiency. The UNC coarse thread and Class 3A fit ensure rapid, secure installation in metals and composites, reducing downtime in production lines. With a Rockwell C39 hardness and robust tensile strength, they resist deformation under load, making them ideal for machinery, automotive, and construction applications. The 82° countersink seamlessly integrates into pre-drilled holes, providing a smooth surface that prevents snagging and improves safety in moving parts.

Specification Summary & Compliance

This screw meets precise dimensional standards, including Class 3A thread fit for accuracy and UNC coarse threading with a 1/4"-20 size. It complies with ASTM F835 specifications for mechanical properties, ensuring consistent quality. Additionally, it is RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, adhering to environmental and safety regulations for global industrial use.