S-91255A848 1/2"-20 x 4" ASTM F835 Steel Button Head Hex-Drive Screws

Key Features & Benefits at a Glance

• Exceptional Tensile Strength – With 120,000 psi tensile strength, this screw provides superior load-bearing capacity for demanding industrial applications, reducing the risk of fastener failure.
• Precision Class 3A Thread Fit – Ensures tight, secure connections with minimal backlash, ideal for machinery and assemblies requiring high vibration resistance.
• Corrosion-Resistant Black-Oxide Finish – The alloy steel with black-oxide coating offers enhanced durability and protection against rust in harsh environments.
• Optimized Hex Drive Design – A 5/16" hex drive allows for high-torque installation with standard tools, speeding up assembly while preventing stripping.
• Fully Threaded 4" Length – Delivers consistent clamping force along the entire shank, accommodating varied material thicknesses without compromising grip.
• Fine Thread Spacing (UNF) – Provides improved adjustment accuracy and better retention in dynamic or high-stress conditions compared to coarse threads.
• Rounded Button Head Profile – Offers a low-profile, smooth finish that minimizes snagging and enhances safety in exposed applications.

Professional Applications & Engineering Value

Engineered for high-stress industrial environments, this Black-Oxide Alloy Steel rounded head screw addresses common challenges like vibration loosening and corrosion. The Class 3A UNF fine thread ensures precise engagement in critical assemblies, from heavy machinery to automotive systems, where tolerance integrity is paramount. Its fully threaded 4" length and 120,000 psi tensile strength provide reliable performance under cyclic loads, while the hex drive facilitates quick, secure installation. Ideal for OEM and MRO applications, this fastener combines material durability with thread precision to reduce maintenance intervals and enhance operational safety.

Specification Summary & Compliance

This screw meets ASME B18.3 and ASTM F835 specifications, ensuring dimensional accuracy and manufacturing consistency. Threads conform to UNF Class 3A tolerances for fine spacing and tight fit. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, guaranteeing environmental safety and material traceability for global supply chains.