S-91253A881 5/8"-18 x 3 1/2" 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 alloy steel construction offers enhanced corrosion resistance, extending service life in harsh environments without compromising structural integrity.
• 82° countersink angle and flat head design allows for flush mounting, minimizing protrusion and improving aerodynamics or safety in assembled components.
• Partially threaded shank enables better grip and alignment control, ideal for applications requiring precise clamping force distribution.
• 3/8" hex drive facilitates easy installation and removal with standard tools, reducing assembly time and labor costs.
• Compliance with ASTM F835, RoHS, and REACH ensures adherence to industry standards for safety, environmental responsibility, and material quality.

Professional Applications & Engineering Value

This 5/8"-18 UNF flat head screw is engineered to address common industrial challenges such as vibration loosening and corrosion-induced degradation. Crafted from black-oxide alloy steel, it combines high Rockwell C37 hardness with a 130,000 PSI tensile strength to withstand heavy loads and repetitive stress in machinery, automotive, and construction sectors. The fine UNF thread and Class 3A fit ensure secure fastening in precision assemblies, while the 82° countersink angle provides a seamless finish, reducing snag hazards. Ideal for applications demanding corrosion resistance and long-term reliability, this screw minimizes maintenance needs and enhances operational efficiency in demanding environments.

Specification Summary & Compliance

This product features a Class 3A thread fit with precise dimensional accuracy per UNF standards, including a thread size of 5/8"-18 and partial threading. It complies with ASTM F835 manufacturing specifications and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material quality for industrial use.