S-91251A200 2-56 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 tighter tolerances for secure, vibration-resistant assemblies, enhancing joint integrity.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread form and drive integrity through repeated use.
• Coarse UNC threads enable quicker installation and better performance in materials prone to stripping or where rapid assembly is critical.
• Partially threaded design allows for controlled clamping force and reduced risk of cross-threading in precision applications.
• Compliance with ASTM A574, RoHS 3, and REACH ensures material consistency and environmental safety, meeting global regulatory standards.

Professional Applications & Engineering Value

Engineered for demanding industrial settings, these black-oxide alloy steel socket head cap screws address common challenges like vibration loosening and environmental degradation. The 2-56 UNC coarse threads with Class 3A fit deliver superior grip in soft metals or plastics, preventing strip-out while the 170,000 psi tensile strength and Rockwell C37 hardness withstand dynamic loads. Ideal for machinery, automotive, and electronics assembly, the partially threaded configuration ensures precise engagement, reducing installation errors. The black-oxide surface treatment adds a protective layer against moisture and chemicals, extending fastener life in corrosive conditions without compromising drive performance with the 5/64" hex drive.

Specification Summary & Compliance

This screw adheres to UNC coarse thread standards with a Class 3A thread fit for high precision. Manufacturing follows ASTM A574 specifications, ensuring consistent quality and performance. The product is fully RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, confirming it is free of restricted hazardous substances and safe for various industrial applications.