S-91251A649 3/8"-16 x 4 1/4" 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 hardness rating of Rockwell C37 provides excellent wear resistance and durability, extending the service life of the screw in industrial environments.
• Precise Class 3A thread fit offers tighter tolerances for secure, vibration-resistant connections, minimizing loosening in machinery and equipment.
• Black-oxide coating on alloy steel enhances corrosion resistance and provides a sleek, low-glare finish, ideal for both functional and aesthetic requirements.
• Coarse UNC threads enable quick and easy installation, reducing assembly time and improving efficiency in production lines.
• Partially threaded design allows for controlled clamping force, preventing over-tightening and ensuring even load distribution.
• 5/16" hex drive compatibility facilitates straightforward installation with standard tools, streamlining maintenance and repair processes.

Professional Applications & Engineering Value

This Black-Oxide Alloy Steel Socket Head Cap Screw is engineered to address common industrial challenges, such as vibration-induced loosening and corrosion in harsh environments. The 3/8"-16 UNC coarse thread and Class 3A fit provide a secure, high-strength connection that withstands dynamic loads, making it ideal for heavy machinery, automotive assemblies, and structural frameworks. The partially threaded rod type ensures precise clamping without thread damage, while the black-oxide surface treatment adds a protective layer against moisture and chemicals. By combining robust alloy steel with strict manufacturing standards, this screw delivers consistent performance in applications requiring reliability, ease of installation, and compliance with industry regulations.

Specification Summary & Compliance

This socket head cap screw features a 3/8"-16 UNC coarse thread with Class 3A fit for precise dimensional accuracy, and a minimum thread length of 1-1/4". It meets ASTM A574 specifications for high-strength fasteners and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) standards, ensuring environmental safety and industrial reliability.