S-91253A871 5/8"-18 x 1 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 industrial applications, reducing the risk of fastener failure.
• Class 3A thread fit provides superior precision and tighter tolerances for secure, vibration-resistant assemblies in critical machinery.
• Black-oxide coating on alloy steel offers enhanced corrosion resistance and durability, extending service life in harsh environments.
• Fully threaded design with UNF fine threads delivers maximum grip and uniform load distribution, ideal for fine-adjustment applications.
• 82° countersink angle and flat head allows for a flush, low-profile installation, improving aesthetics and reducing snag hazards.
• Hex drive (3/8") enables easy installation and high torque application with standard tools, speeding up assembly processes.
• Compliance with ASTM F835, RoHS 3, and REACH ensures adherence to international quality and environmental standards, supporting responsible sourcing.

Professional Applications & Engineering Value

This black-oxide alloy steel flat head screw is engineered to address common industrial challenges such as vibration loosening and corrosion in heavy-duty equipment. The UNF fine thread (5/8"-18) and Class 3A fit provide exceptional clamping force and resistance to dynamic loads, making it ideal for precision assemblies in machinery, automotive, and aerospace sectors. The fully threaded right-hand design ensures consistent engagement, while the 82° countersink facilitates seamless integration into angled surfaces. With a Rockwell C37 hardness and robust 130,000 psi tensile strength, it delivers long-term reliability in demanding applications, reducing maintenance downtime and enhancing operational safety.

Specification Summary & Compliance

This screw features precise Class 3A thread fit per UNF standards, with a thread size of 5/8"-18 and fine spacing. Dimensions include a length of 1 3/4", head diameter of 1.188", and drive size of 3/8" hex. It meets ASTM F835 specifications for mechanical properties and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material integrity for global industrial use.