S-91251A878 7/8"-9 x 1 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.
• Superior corrosion resistance from the black-oxide finish prolongs service life in harsh industrial environments, minimizing maintenance needs.
• Precise Class 3A thread fit provides tight, secure fastening with minimal backlash, enhancing assembly accuracy and joint integrity.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread form and drive integrity through repeated use.
• 3/4" hex drive design allows for high-torque installation with standard tools, speeding up assembly and reducing labor time.
• Fully threaded UNRC coarse thread enables quick engagement and strong holding power in a wide range of materials.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency, environmental safety, and global regulatory acceptance.

Professional Applications & Engineering Value

This black-oxide alloy steel socket head cap screw is engineered to address critical challenges in heavy-duty applications, such as machinery assembly, automotive frames, and structural fabrications. The combination of high tensile strength (170,000 psi) and Rockwell C37 hardness provides resilience against dynamic loads and vibration, preventing loosening and fatigue failures. The coarse UNRC thread and Class 3A fit ensure rapid, secure fastening in both soft and hard materials, reducing installation time while maintaining clamp force. Its black-oxide surface treatment adds a layer of corrosion resistance, making it suitable for environments exposed to moisture or chemicals. These features make it an ideal choice for engineers seeking durable, high-performance industrial fasteners that enhance equipment longevity and operational safety.

Specification Summary & Compliance

This socket head cap screw adheres to Class 3A thread tolerances for precise fit and UNRC coarse thread standards with a 7/8"-9 thread size. It is manufactured in compliance with ASTM A574 specifications, ensuring consistent material properties and performance. The product is also verified as RoHS 3 (2015/863/EU) Compliant and REACH (EC 1907/2006) Compliant, confirming it meets stringent environmental and health safety regulations for global use.