S-91253A081 2-56 x 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 high-stress conditions, reducing the risk of fastener failure in demanding applications.
• Black-oxide finish on alloy steel provides superior corrosion resistance and a durable, non-reflective surface ideal for industrial environments.
• Class 3A thread fit offers tighter tolerances for precise, secure mating with nuts and tapped holes, minimizing backlash and vibration loosening.
• 82° countersink angle and flat head design allows for a flush installation, preventing snagging and ensuring a clean, aerodynamic surface finish.
• Hex drive (0.050") enables high-torque installation with common tools, speeding up assembly while reducing strip-out risks.
• Fully threaded UNC coarse thread facilitates quick engagement and strong holding power, even in materials with varying densities.
• Rockwell C39 hardness enhances wear resistance and longevity, maintaining thread integrity through repeated use and disassembly.

Professional Applications & Engineering Value

This 2-56 UNC flat head screw is engineered to address common industrial challenges such as vibration-induced loosening and corrosion in harsh environments. The black-oxide alloy steel construction, combined with a Class 3A thread fit, ensures a secure, vibration-resistant connection that maintains integrity in machinery, electronics, and automotive assemblies. The 82° countersink angle and fully threaded coarse UNC design allow for rapid, flush installations in metal, plastic, or composite materials, reducing assembly time while providing consistent clamping force. Ideal for applications requiring high tensile strength and compliance with rigorous industry standards, these screws deliver reliable performance in precision engineering and heavy-duty equipment.

Specification Summary & Compliance

This screw adheres to precise dimensional standards with a Class 3A thread fit and UNC coarse threading for optimal engagement. It meets ASME B18.3 and ASTM F835 specifications, ensuring consistent quality and performance. Compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, it is free of hazardous substances, making it suitable for global industrial and electronic applications.