S-91251A902 7/8"-9 x 9" 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 demanding applications.
• Superior corrosion resistance from the black-oxide finish extends service life and maintains integrity in harsh industrial environments.
• Precise Class 3A thread fit provides tight, secure connections with minimal backlash, enhancing assembly accuracy and vibration resistance.
• High hardness rating (Rockwell C37) offers excellent wear resistance, prolonging fastener durability and reducing maintenance needs.
• 3/4" hex drive design allows for easy installation and high torque application with standard tools, speeding up assembly processes.
• Coarse UNRC threads enable quick engagement and reduced cross-threading risks, ideal for rapid installations and disassemblies.
• Compliance with ASTM A574 guarantees consistent quality and mechanical properties, ensuring reliability in critical engineering applications.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address common industrial challenges such as vibration loosening, corrosion-induced degradation, and high-load failures. The partially threaded rod design with coarse UNRC threads provides optimal grip in materials like steel and cast iron, while the socket head allows for compact installations in confined spaces. Its high tensile strength and Rockwell C37 hardness make it suitable for heavy machinery, automotive assemblies, and structural frameworks where durability and precision are critical. The black-oxide surface treatment enhances corrosion resistance without sacrificing dimensional stability, offering long-term reliability in outdoor or chemically exposed environments. This fastener delivers consistent performance in applications requiring Class 3A thread fit and compliance with industry standards, reducing downtime and maintenance costs.

Specification Summary & Compliance

This socket head cap screw features a 7/8"-9 coarse thread with Class 3A thread fit for precise tolerances, and a partially threaded design with a minimum thread length of 2 1/4". It complies with ASTM A574 specifications for material and mechanical properties, and meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, ensuring safe and sustainable use in global industrial markets.