S-91263A350 5/16"-24 x 3/4" 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 in high-stress applications, reducing the risk of fastener failure
• Superior corrosion resistance from zinc plating protects against rust and extends service life in demanding industrial environments
• Precise Class 3A thread fit guarantees secure fastening with minimal backlash, improving assembly accuracy and vibration resistance
• 82° countersink angle design allows for flush mounting in standard countersunk holes, creating smooth surfaces and enhanced aesthetics
• Hex drive compatibility provides secure tool engagement during installation, preventing cam-out and ensuring consistent torque application
• Full threading along the entire length enables maximum grip strength and uniform load distribution across joined materials
• Rockwell C39 hardness rating maintains thread integrity and prevents stripping during repeated installation and removal cycles

Professional Applications & Engineering Value

These zinc-plated alloy steel flat head screws deliver critical performance advantages in industrial applications where reliability and precision are paramount. The combination of UNF fine threading with Class 3A fit addresses common challenges in machinery assembly, providing superior vibration resistance compared to coarse thread alternatives. The 82° countersink angle ensures proper seating in standard chamfered holes, eliminating protrusions that could interfere with moving components. Engineered for heavy-duty applications, these fully threaded screws distribute clamping force evenly, preventing joint loosening in equipment subjected to dynamic loads. The hex drive design facilitates efficient installation in confined spaces, while the zinc plating provides essential corrosion protection for extended service life in manufacturing, automotive, and industrial equipment applications.

Specification Summary & Compliance

This fastener meets precise dimensional requirements with Class 3A thread fit per UNF standards, ensuring tight tolerances for critical applications. Manufacturing complies with ASTM F835 specifications for mechanical properties and performance. The product is certified RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, meeting current environmental regulations for hazardous substances. Thread specifications include 5/16"-24 UNF fine threading with right-hand direction, designed for optimal performance in precision assemblies requiring fine adjustment capabilities.