S-91251A162 4-40 x 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 in demanding applications.
• Class 3A thread fit provides tighter tolerances for superior engagement and vibration resistance, enhancing assembly integrity in precision machinery.
• Black-oxide coating on alloy steel offers excellent corrosion resistance and a durable, low-glare finish suitable for harsh industrial environments.
• Partially threaded design allows for secure clamping in specific zones without unnecessary threading, optimizing load distribution and ease of installation.
• Rockwell C37 hardness ensures long-term wear resistance and durability, minimizing deformation and maintenance needs over time.
• Coarse UNC threads enable quick assembly and disassembly, reducing labor time and improving efficiency in high-volume production settings.
• Hex socket drive (3/32") facilitates easy access in confined spaces, allowing for precise torque application with standard tools.

Professional Applications & Engineering Value

This 4-40 UNC thread socket head cap screw is engineered to address common industrial challenges, such as vibration loosening and corrosion in heavy-duty equipment. Made from black-oxide alloy steel, it combines high Rockwell C37 hardness and 170,000 psi tensile strength to withstand extreme mechanical stresses, making it ideal for applications in automotive assemblies, aerospace components, and precision machinery. The coarse thread and Class 3A fit ensure secure fastening in dynamic environments, while the partially threaded rod design provides focused clamping force, reducing the risk of thread stripping. Compliant with ASTM A574, it offers reliable performance in sectors requiring adherence to strict engineering standards, enhancing operational safety and reducing downtime.

Specification Summary & Compliance

This screw features precise Class 3A thread fit with UNC coarse threads and a 2" length with a minimum thread length of 3/4". It meets ASTM A574 specifications for high-strength fasteners and is compliant with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) regulations, ensuring environmental safety and material reliability for global industrial use.