S-91253A868 5/8"-18 x 1 1/4" 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 under high-stress conditions, reducing the risk of fastener failure.
• Precise Class 3A thread fit provides superior engagement and vibration resistance, minimizing loosening in critical assemblies.
• Black-oxide finish on alloy steel offers enhanced corrosion resistance and a durable, non-reflective surface for harsh environments.
• Fully threaded design allows for maximum grip length and uniform clamping force across the entire fastener.
• 82° countersink angle with standard flat head profile enables flush mounting for a clean, aerodynamic finish and improved safety.
• 3/8" hex drive facilitates easy installation and high torque application with standard tools, speeding up assembly processes.
• Compliance with ASTM F835, RoHS 3, and REACH ensures material quality, environmental safety, and suitability for regulated industries.

Professional Applications & Engineering Value

This 5/8"-18 UNF flat head socket cap screw is engineered to address common industrial challenges such as vibration-induced loosening and corrosion in demanding applications. The black-oxide alloy steel construction, combined with a fine thread spacing and Class 3A thread fit, delivers superior holding power and resistance to dynamic loads, making it ideal for machinery, automotive, and heavy equipment assemblies. The fully threaded design ensures consistent load distribution, while the 82° countersink angle allows for seamless integration into components requiring a smooth surface. By meeting ASTM F835 specifications, it guarantees reliability in high-strength scenarios, reducing maintenance needs and enhancing operational longevity.

Specification Summary & Compliance

This screw adheres to Class 3A thread fit for precise UNF fine threading, with dimensions including a 5/8"-18 thread size, 1-1/4" length, and 3/8" hex drive. It conforms to ASTM F835 for mechanical properties, ensuring high tensile strength and hardness (Rockwell C37). Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming environmental safety and material integrity for global industrial use.