S-91251A176 1 1/8"-7 x 8" ASTM A574 Alloy Steel Socket Head Screws

Key Features & Benefits at a Glance

• Exceptional tensile strength of 170,000 psi ensures reliable performance under extreme loads, reducing the risk of fastener failure in demanding applications.
• Superior corrosion resistance from the black-oxide finish on alloy steel, extending service life and maintaining integrity in harsh industrial environments.
• High hardness rating (Rockwell C37) provides excellent wear resistance, minimizing deformation and maintaining thread integrity during repeated use.
• Coarse UNRC threads allow for faster installation and better debris clearance, improving efficiency in assembly and maintenance operations.
• Partially threaded design offers precise clamping control, preventing over-tightening and ensuring secure fastening in critical joints.
• Standard hex socket drive (7/8") enables high-torque application with common tools, facilitating easy installation and removal in confined spaces.
• Compliance with ASTM A574 guarantees consistent quality and dimensional accuracy, meeting rigorous industrial standards for socket head cap screws.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address common challenges in heavy machinery, construction, and automotive assembly where vibration resistance and high clamp load retention are critical. The UNRC coarse thread design minimizes cross-threading risks and provides superior holding power in softer materials or high-vibration environments. With its partially threaded shank, it ensures that the unthreaded portion bears against connected parts, distributing stress evenly and preventing joint loosening. The combination of 170,000 psi tensile strength and Rockwell C37 hardness makes it ideal for applications requiring repeated disassembly and reassembly without compromising fastener integrity. These features collectively enhance operational reliability, reduce maintenance downtime, and provide long-term cost savings in industrial fastening systems.

Specification Summary & Compliance

This socket head cap screw adheres to Class 2A thread fit for consistent assembly compatibility and meets ASTM A574 specifications for high-strength alloy steel fasteners. It is fully RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, ensuring environmental safety and regulatory adherence for global industrial use. Dimensions include an 8" length with a 1 1/8"-7 coarse thread and 7/8" hex drive, manufactured to precise inch system tolerances for reliable performance.