S-91253A310 1/4"-28 x 9/16" ASTM F835 Alloy Steel Hex Drive Flat Head Screws

Key Features & Benefits at a Glance

• Exceptional durability with Rockwell C39 hardness and 130,000 psi tensile strength, ensuring reliable performance in high-stress industrial environments.
• Superior corrosion resistance from the black-oxide finish on alloy steel, extending service life in demanding conditions.
• Precise, secure fastening with Class 3A thread fit and UNF fine threads, minimizing the risk of loosening under vibration.
• Easy installation and removal thanks to the 5/32" hex drive, allowing for efficient assembly with standard tools.
• Flush surface finish achieved with the standard flat head and 82° countersink angle, ideal for applications requiring a smooth, unobtrusive profile.
• Full threading for maximum grip across the entire 9/16" length, providing consistent holding power in various materials.
• Compliance with industry standards including ASTM F835, RoHS 3, and REACH, ensuring safety and environmental responsibility.

Professional Applications & Engineering Value

This 1/4"-28 UNF Class 3A 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 offers enhanced resistance to wear and oxidation, making it suitable for machinery, automotive assemblies, and electronic enclosures where durability is critical. The fine UNF threads and Class 3A fit provide tight tolerances, reducing the need for frequent maintenance and ensuring long-term reliability in precision applications. Its fully threaded design and 82° countersink angle allow for seamless integration into countersunk holes, promoting aerodynamic or aesthetic finishes in aerospace and consumer goods. By combining high tensile strength with regulatory compliance, this screw delivers consistent performance for engineers and procurement specialists seeking robust industrial fasteners.

Specification Summary & Compliance

This product adheres to precise dimensional standards, including Class 3A thread fit for tight tolerances and UNF fine threading with a 1/4"-28 size. It meets ASTM F835 specifications for mechanical properties and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring it is free from hazardous substances and safe for various industrial uses.