S-91263A250 1/4"-28 x 1/2" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with zinc-plated alloy steel construction for extended service life in harsh industrial environments
• Exceptional load-bearing capability with 130,000 PSI tensile strength to withstand high-stress applications without failure
• Precise thread engagement with Class 3A fit and UNF fine threading for secure, vibration-resistant fastening
• Optimized flush mounting with 82° countersink angle and standard flat head profile for seamless surface integration
• Enhanced installation efficiency with 5/32" hex drive providing reliable torque transmission and reduced tool slippage
• Consistent mechanical performance with Rockwell C39 hardness ensuring dimensional stability under repeated use
• Full-threaded design offering maximum grip length and uniform stress distribution along the entire fastener

Professional Applications & Engineering Value

These 1/4"-28 UNF flat head screws deliver critical engineering solutions where flush surface mounting and high-strength fastening are paramount. The zinc-plated alloy steel construction provides essential corrosion protection for industrial equipment, machinery assemblies, and outdoor applications. The Class 3A thread fit with UNF fine threading ensures precise engagement in tapped holes, preventing loosening from vibration - a common failure point in dynamic systems. The 82° countersink angle allows for seamless integration into precision-machined components, while the 5/32" hex drive facilitates efficient installation in confined spaces. With fully threaded design and 130,000 PSI tensile strength, these screws maintain structural integrity in high-load applications across automotive, manufacturing, and heavy equipment sectors.

Specification Summary & Compliance

Manufactured to exacting inch system dimensions with Class 3A thread fit tolerance and UNF (Unified National Fine) thread standard. Complies with ASTM F835 specifications for mechanical properties and performance requirements. Meets environmental regulations including RoHS 3 (2015/863/EU) compliance and REACH (EC 1907/2006) standards for restricted substances. Features right-hand thread direction with fine thread spacing for precision applications.