S-91255A056 5/8"-11 x 2 1/2" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional durability with 120,000 psi tensile strength and Rockwell C37 hardness, ensuring reliable performance under high-stress conditions
• Superior corrosion resistance thanks to the black-oxide finish on alloy steel, extending service life in harsh industrial environments
• Secure and efficient installation with a 3/8" hex drive and fully threaded UNC coarse spacing, reducing assembly time and preventing stripping
• Precise thread engagement with Class 3A fit, minimizing the risk of cross-threading and ensuring consistent clamping force
• Broad compliance with ASME B18.3 and ASTM F835 standards, guaranteeing dimensional accuracy and mechanical properties for critical applications
• Environmental and safety adherence through RoHS 3 and REACH compliance, supporting sustainable and safe manufacturing practices
• Versatile rounded button head design that provides a low-profile, finished appearance while distributing load effectively

Professional Applications & Engineering Value

This 5/8"-11 UNC rounded head hex screw is engineered to address common industrial challenges such as vibration loosening, corrosion-induced failure, and assembly inefficiency. The black-oxide alloy steel construction offers enhanced resistance to rust and wear, making it ideal for outdoor equipment, heavy machinery, and structural assemblies exposed to moisture or chemicals. The fully threaded coarse spacing and Class 3A thread fit ensure quick, secure fastening in materials like steel and cast iron, reducing downtime in production lines. Its high tensile strength and standardized dimensions per ASME B18.3 provide reliable performance in demanding applications, from construction to automotive manufacturing, where consistent clamping force and longevity are critical.

Specification Summary & Compliance

This screw adheres to precise dimensional and mechanical standards, including Class 3A thread fit for tight tolerances and UNC coarse thread specifications. It meets ASME B18.3 and ASTM F835 for consistent quality and performance. Additionally, it is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006), ensuring it is free from hazardous substances and suitable for global supply chains.