S-91251A233 4-40 x 1 5/8" 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.
• Superior corrosion resistance from the black-oxide finish extends service life in demanding industrial environments.
• Precise Class 3A thread fit provides secure, vibration-resistant connections for critical assemblies.
• High hardness rating (Rockwell C37) enhances wear resistance and maintains thread integrity through repeated use.
• Compact hex drive design (3/32") allows easy installation in confined spaces with standard tools.
• Partially threaded shank offers optimal grip length for materials of varying thicknesses without compromising strength.
• Compliance with ASTM A574, RoHS 3, and REACH guarantees material consistency and environmental safety for global supply chains.

Professional Applications & Engineering Value

Engineered for high-strength industrial fastening, these black-oxide alloy steel socket head cap screws address common challenges like vibration loosening and corrosion in machinery, automotive, and aerospace assemblies. The 4-40 UNC coarse threads and Class 3A fit ensure quick installation and reliable clamping force, while the partially threaded design minimizes stress concentration. Ideal for applications requiring compact hex drive access, they provide durability in environments exposed to oils, moisture, and temperature variations, reducing maintenance cycles and downtime.

Specification Summary & Compliance

This screw meets ASTM A574 specifications for high-strength metric and inch socket head cap screws, with Class 3A thread fit ensuring tight tolerances per UNC standards. It is fully RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) compliant, confirming adherence to environmental and safety regulations for industrial use worldwide.