S-91251A408 6-40 x 3/8" 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.
• Class 3A thread fit provides superior precision and tighter tolerances for secure, vibration-resistant assemblies in critical applications.
• Black-oxide coating on alloy steel offers enhanced corrosion resistance and a durable, non-reflective finish for extended service life.
• Fully threaded design allows for maximum grip and adjustability along the entire length, simplifying installation and improving holding power.
• Hex socket drive (7/64") enables high-torque application with standard tools, minimizing stripping and ensuring efficient assembly in confined spaces.
• Rockwell C37 hardness delivers excellent wear resistance and durability, maintaining thread integrity through repeated use.
• Compliance with ASTM A574, RoHS 3, and REACH guarantees material quality and environmental safety, meeting rigorous industrial and regulatory standards.

Professional Applications & Engineering Value

Engineered for demanding environments, this 6-40 UNF fine thread socket head cap screw addresses common industrial challenges such as vibration loosening and material fatigue. The black-oxide alloy steel construction, combined with a Class 3A thread fit, ensures precise alignment and secure fastening in machinery, automotive assemblies, and precision equipment. Its fully threaded and right-hand thread design facilitates easy adjustment and uniform load distribution, reducing stress concentrations. Ideal for applications requiring high tensile strength and corrosion resistance, this screw provides long-term reliability in aerospace, manufacturing, and electronics, where fastener integrity is critical to operational safety and efficiency.

Specification Summary & Compliance

This socket head cap screw features a 6-40 UNF fine thread with Class 3A precision fit, ensuring tight tolerances per unified thread standards. Dimensions include a 3/8" length, 0.226" head diameter, and 7/64" hex drive for consistent performance. Manufactured in compliance with ASTM A574 specifications, it meets RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) environmental regulations, affirming its suitability for global industrial use without hazardous substances.