S-91251A113 4-40 x 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 hardness rating of Rockwell C37 provides excellent wear resistance and durability for long-term use in demanding environments.
• Black-oxide coating on alloy steel offers enhanced corrosion resistance and a sleek, non-reflective finish suitable for various industrial settings.
• Precise Class 3A thread fit guarantees tight tolerances and secure fastening, minimizing loosening under vibration and load.
• Hex socket drive design allows for high torque application and easy installation in confined spaces with standard tools.
• Full threading along the 3/4" length enables adjustable positioning and consistent clamping force across the entire fastener.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material quality, environmental safety, and regulatory adherence for global supply chains.

Professional Applications & Engineering Value

Engineered for precision and resilience, these 4-40 UNC thread socket head cap screws are ideal for industrial assembly, machinery, and electronic enclosures where space constraints and high strength are critical. The black-oxide alloy steel construction combats corrosion while maintaining a low profile, making them suitable for automotive, aerospace, and manufacturing applications. The coarse UNC thread and Class 3A fit provide rapid installation and vibration resistance, addressing common issues like thread stripping and loosening. With a hex drive and fully threaded design, they ensure efficient torque transfer and versatile fastening in tight areas, enhancing assembly speed and reliability for B2B technical projects.

Specification Summary & Compliance

This screw features a 4-40 UNC coarse thread with Class 3A precision fit, ensuring dimensional accuracy and interchangeability. It adheres to ASTM A574 specifications for high-strength alloy steel, and is fully compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, confirming it is free from hazardous substances and suitable for international engineering standards.