S-91251A391 5/16"-24 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.
• Superior corrosion resistance from the black-oxide finish extends service life in demanding industrial environments.
• Precise Class 3A thread fit provides consistent engagement and vibration resistance, minimizing loosening in critical assemblies.
• High hardness (Rockwell C37) offers excellent wear resistance, maintaining thread integrity through repeated use.
• Fine UNF thread design allows for finer adjustments and improved clamping force control in precision applications.
• Partially threaded shank concentrates threads where needed, providing optimal grip without unnecessary weight or material.
• Standard hex socket drive enables easy installation with common tools, reducing assembly time and effort.

Professional Applications & Engineering Value

These Black-Oxide Alloy Steel Socket Head Cap Screws are engineered to address common industrial challenges such as vibration-induced loosening and environmental corrosion. The fine UNF thread (5/16"-24) and Class 3A fit ensure tight tolerances and secure fastening in precision machinery, automotive components, and heavy equipment. The alloy steel construction combined with 170,000 psi tensile strength provides the durability needed for high-load applications, while the black-oxide surface treatment offers an added layer of protection against rust and wear. Ideal for use in assembly lines, manufacturing fixtures, and structural frameworks, these screws deliver consistent performance where reliability is non-negotiable.

Specification Summary & Compliance

This product adheres to ASTM A574 specifications, ensuring material and manufacturing consistency. The Class 3A thread fit guarantees precise dimensional accuracy, while the UNF fine thread standard maintains compatibility with industry norms. Compliance with RoHS 3 (2015/863/EU) and REACH (EC 1907/2006) confirms environmental safety and regulatory alignment, making these screws suitable for global supply chains and sensitive applications.