S-91253A131 5-40 x 3/4" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with Black-Oxide finish, extending service life in demanding industrial environments
• Exceptional mechanical strength with 130,000 psi tensile strength and Rockwell C39 hardness for reliable performance under high stress
• Precise Class 3A thread fit ensures secure fastening and vibration resistance in critical assemblies
• Optimized flush mounting with 82° countersink angle and flat head design for smooth surface finishes
• Enhanced installation efficiency through hex drive design providing superior torque transmission and slip resistance
• Full threading capability delivers maximum grip length and uniform load distribution across the entire fastener
• Industry-standard compliance guarantees consistent quality and interchangeability across applications

Professional Applications & Engineering Value

These 5-40 UNC flat head screws with Black-Oxide Alloy Steel construction address critical engineering challenges in industrial fastening. The combination of Class 3A thread fit and coarse UNC threading provides exceptional vibration resistance and rapid assembly in high-stress applications including machinery, automotive components, and electronic enclosures. The 82° countersink angle ensures perfect flush mounting while the hex drive prevents cam-out during high-torque installation. With fully threaded design maximizing engagement strength, these screws deliver reliable performance in applications requiring repeated disassembly and reassembly cycles.

Specification Summary & Compliance

Manufactured to precise Class 3A thread fit tolerances with UNC coarse thread profile (5-40 thread size). Complies with ASME B18.3 and ASTM F835 manufacturing specifications. Meets environmental standards including RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliance. Features standard right-hand thread direction and consistent dimensional accuracy throughout production batches.