S-91251A643 1 1/2"-12 x 5 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 in demanding applications.
• Black-oxide coating on alloy steel provides enhanced corrosion resistance, extending service life in harsh industrial environments.
• UNRF fine thread design offers superior vibration resistance and improved clamping force compared to coarse threads, ideal for precision assemblies.
• Partially threaded shank allows for precise grip length control, minimizing thread damage and simplifying installation in specific mounting scenarios.
• Hex socket drive enables high-torque installation with standard tools, ensuring secure fastening without stripping the drive.
• Class 2A thread fit guarantees consistent, easy assembly with standard nuts and tapped holes, reducing installation time and labor costs.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material quality and environmental safety, meeting rigorous industrial and regulatory standards.

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 loosening and corrosion are common issues. The UNRF fine thread design enhances fatigue resistance, maintaining clamp load under dynamic stresses, while the alloy steel construction with Rockwell C37 hardness provides durability against wear and impact. The black-oxide surface treatment not only resists rust but also reduces galling during installation, making it suitable for high-torque applications in assembly lines and structural frameworks. Its partially threaded configuration allows engineers to optimize load distribution, preventing thread damage in blind holes and ensuring long-term reliability in industrial fastening systems.

Specification Summary & Compliance

This socket head cap screw adheres to Class 2A thread fit per UNRF standards, ensuring precise dimensional accuracy and interchangeability. Manufactured in accordance with ASTM A574 specifications, it meets rigorous mechanical properties for high-strength fasteners. The product is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming the absence of restricted hazardous substances and supporting environmentally responsible procurement.