S-91251A468 1/4"-28 x 3 1/2" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance under high-stress conditions, reducing the risk of fastener failure in critical applications.
• Superior corrosion resistance from the black-oxide finish on alloy steel extends service life in demanding industrial environments, minimizing maintenance needs.
• Precise Class 3A thread fit provides tight tolerances and secure fastening, enhancing assembly integrity and vibration resistance.
• Fine UNRF thread design offers improved load distribution and better retention in materials prone to stripping, increasing joint stability.
• Hex socket drive allows for high-torque installation with standard tools, enabling efficient assembly and disassembly in confined spaces.
• Rockwell C37 hardness balances durability and machinability, resisting wear while maintaining ease of use in repetitive applications.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety, meeting global regulatory standards for industrial procurement.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address common industrial challenges such as vibration loosening and corrosion in heavy machinery, automotive, and aerospace assemblies. The 1/4"-28 UNRF fine thread and Class 3A fit deliver superior clamping force and fatigue resistance, preventing joint failure in dynamic loads. Its partially threaded design concentrates strength where needed, while the hex drive facilitates quick installation with standard wrenches, reducing labor time. Ideal for high-stress environments, this fastener combines 170,000 psi tensile strength with a protective coating to endure harsh conditions, ensuring long-term reliability and reduced downtime.

Specification Summary & Compliance

This product adheres to Class 3A thread fit for precise dimensional accuracy under the UNRF fine thread standard, with a minimum thread length of 1 inch. Manufactured in compliance with ASTM A574 specifications for high-strength socket head cap screws, it meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe and sustainable use in industrial applications.