S-91255A587 5/16"-18 x 1 1/2" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 120,000 PSI for reliable performance in high-stress industrial applications.
• Superior corrosion resistance provided by the black-oxide finish, extending service life in demanding environments.
• Precise Class 3A thread fit ensures secure, vibration-resistant connections and reduces the risk of assembly failures.
• Robust Rockwell C39 hardness offers excellent wear resistance and maintains thread integrity under repeated use.
• Convenient hex drive design allows for easy installation and removal with standard tools, improving assembly efficiency.
• Full threading along the 1-1/2" length provides maximum grip and uniform load distribution across the entire fastener.
• Compliance with major industry standards including ASME B18.3 and ASTM F835, ensuring consistent quality and reliability.

Professional Applications & Engineering Value

This black-oxide alloy steel rounded head screw is engineered to address critical challenges in heavy-duty assembly, such as vibration loosening and environmental corrosion. The UNC coarse thread design enables quick installation and superior holding power in brittle materials or high-vibration settings like machinery, automotive frames, and construction equipment. Its fully threaded configuration ensures that the entire shank contributes to clamp load, reducing stress concentration points. The hex drive and button head style provide a low-profile, tamper-resistant finish that fits flush in countersunk holes, making it ideal for applications where clearance is limited and a smooth surface is required. By combining high tensile strength with compliant threading, this screw minimizes the risk of strip-out and maintains joint integrity under dynamic loads, offering long-term reliability for industrial fastening solutions.

Specification Summary & Compliance

This screw adheres to precise dimensional standards with a Class 3A thread fit and UNC coarse thread spacing for consistent engagement. It is manufactured in accordance with ASME B18.3 and ASTM F835 specifications, ensuring mechanical performance and interchangeability. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free of restricted hazardous substances and safe for use in various markets.