S-91251A879 7/8"-9 x 1 3/4" 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 harsh industrial environments.
• Precise Class 3A thread fit provides secure, vibration-resistant connections, minimizing loosening in dynamic assemblies.
• Coarse UNRC threads allow for quicker installation and easier alignment, saving valuable assembly time.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use.
• 3/4" hex drive socket head enables high-torque installation with standard tools, ensuring tight, flush fastening.
• Full threading along the 1 3/4" length provides maximum grip and adjustability in a wide range of material thicknesses.

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 where vibration, high loads, and environmental exposure are common. The coarse UNRC thread and Class 3A fit ensure rapid, secure assembly while resisting loosening under dynamic stresses. Its fully threaded design offers versatile clamping across varying material depths, eliminating the need for multiple screw types. The black-oxide surface treatment significantly enhances corrosion resistance, making it ideal for outdoor or humid conditions without sacrificing the 170,000 psi tensile strength required for structural integrity. These features collectively reduce maintenance frequency and improve the reliability of industrial equipment.

Specification Summary & Compliance

This socket head cap screw features a 7/8"-9 UNRC coarse thread with a Class 3A thread fit for high precision. It is manufactured in accordance with ASTM A574 specifications, ensuring consistent quality and performance. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming its safety and environmental standards for global industrial use.