S-91255A846 1/2"-20 x 2 1/2" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Superior corrosion resistance with black-oxide coating, extending service life in demanding industrial environments.
• Exceptional tensile strength (120,000 psi) and hardness (Rockwell C39) for reliable performance under high-stress applications.
• Precise Class 3A thread fit ensures secure, vibration-resistant connections with minimal risk of loosening.
• Fine UNF threading (1/2"-20) provides enhanced clamping force and improved adjustment accuracy.
• Fully threaded design offers consistent engagement along the entire 2 1/2" length for versatile fastening.
• 5/16" hex drive with rounded button head allows for easy installation and a low-profile, finished appearance.
• Compliance with ASME B18.3 and ASTM F835 guarantees dimensional accuracy and material integrity for professional use.

Professional Applications & Engineering Value

This black-oxide alloy steel rounded head hex screw is engineered to address critical challenges in industrial assembly, such as vibration-induced loosening and environmental corrosion. The Class 3A UNF fine thread delivers superior holding power in precision machinery, automotive components, and heavy-duty equipment, where exact torque and clamp load are essential. Its fully threaded 2 1/2" length ensures maximum thread engagement in thick materials or when additional adjustability is required. The combination of 120,000 psi tensile strength and Rockwell C39 hardness makes it ideal for high-stress applications, reducing the risk of fastener failure. The low-profile rounded head and hex drive facilitate easy installation in confined spaces while maintaining a clean, professional finish.

Specification Summary & Compliance

This screw features a 1/2"-20 UNF fine thread with Class 3A fit, ensuring tight tolerances and reliable performance. It is manufactured in accordance with ASME B18.3 and ASTM F835 specifications for dimensional consistency and material properties. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its safety and environmental standards for global industrial use.