S-91251A165 1 1/8"-7 x 4" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance in high-stress applications, reducing the risk of fastener failure.
• Superior corrosion resistance from the black-oxide finish on alloy steel, extending service life in demanding industrial environments.
• Precise Class 2A thread fit provides smooth assembly and secure fastening, minimizing cross-threading and installation errors.
• High torque capability with a 7/8" hex drive and standard socket head profile, allowing for easy installation and removal with standard tools.
• Durable Rockwell C37 hardness maintains structural integrity under heavy loads and repeated use, ensuring long-term reliability.
• Coarse UNRC threads enable quick engagement and superior holding power in a variety of materials, speeding up assembly processes.
• Compliance with ASTM A574, RoHS 3, and REACH guarantees consistent quality and environmental safety for global industrial applications.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical challenges in heavy machinery, automotive, and construction sectors. The 1 1/8"-7 coarse UNRC thread and Class 2A fit ensure rapid, secure fastening in high-vibration environments, reducing maintenance downtime. With a partially threaded design and robust 170,000 psi tensile strength, it provides optimal clamping force without thread damage, ideal for structural assemblies and equipment requiring high-strength fasteners. The black-oxide surface treatment enhances wear and corrosion resistance, making it suitable for outdoor or harsh conditions while meeting strict industry standards for performance and safety.

Specification Summary & Compliance

This socket head cap screw features a 1 1/8"-7 coarse thread with Class 2A tolerance for precise fit, and a 4" length with 2 7/8" minimum thread length. It complies with ASTM A574 specifications for high-strength alloy steel fasteners, and is verified as RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, ensuring adherence to environmental and safety regulations in industrial use.